Fragmentation Drives Dominant Plant Encroachment on a Horizontal Wastewater Treatment Levee

Fragmentation Drives Dominant Plant Encroachment on a Horizontal Wastewater Treatment Levee | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Fragmentation Drives Dominant Plant Encroachment on a Horizontal Wastewater Treatment Levee Joia Fishman, Rachel O'Malley This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8139631/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Urban coastal wetlands protect humans from sea-level rise while providing valuable habitat for wildlife. Degradation and loss of these wetlands threaten urban infrastructure including wastewater treatment facilities. Nature-based adaptive solutions, with the combined purposes of bioremediation, coastal defense, and habitat creation, are being tested to make communities safer and more resilient. The current research examines an experimental horizontal levee installed in 2015 at the Oro Loma Sanitary District in San Lorenzo, California, 5 years after installation. Using quadrat sampling, we compare succession of two plant assemblages – a wet meadow and a riparian scrub community – on an ecotone slope. We use the wet meadow assemblage to document the effects of fragmentation and dominant plant species on plant diversity and abundance. Although most planted species survived from 2015 to 2021, plant diversity decreased over time in both communities. Fragmentation was associated with encroachment by a native dominant willow ( Salix lasiolepis) and an invasive nonnative jubatagrass ( Cortaderia jubata) in the wet meadow. Both fragmentation and the presence of the willow or cattails ( Typha ) correlated with reduced native species diversity and cover. In the absence of natural disturbance processes, created wetlands, especially fragmented wetlands with substantial edge, may progress to a successional state dominated by a few species. Future projects might benefit from specifying habitat creation goals in addition to wastewater treatment goals, selecting native plant assemblages that inhibit succession, planting larger patches, and incorporating natural or human disturbance to break dominance cycles. horizontal levee green infrastructure wastewater treatment created wetland habitat fragmentation Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction California has lost about 80% of its historical wetlands to alteration, draining, or filling (Zedler 2004 ). Worldwide, 21% of wetlands have been lost since the 1700s (Fluet-Chouinard et al. 2023 ). Wetlands provide habitat for flora and fauna, protect coasts from sea-level rise and flooding, improve water quality, and serve as important ecosystems for carbon sequestration (Zedler & Kercher, 2005 ). In contrast, engineered protections from sea-level rise, such as sea walls, generally harm biodiversity (Duarte et al., 2013 ). Costanza et al. ( 2008 ) calculated that, as of 2008, coastal wetlands provided $ 23.3 billion (U.S.) per year in storm protection services alone, as well as crucial habitat for sensitive species. Reestablishing lost wetland biodiversity through restoration can be difficult. Wetlands are particularly susceptible to the formation of vegetative monotypes, because they are landscape sinks (Zedler & Kercher, 2004 ), often occurring in low-lying areas that accumulate nutrients, propagules, sediments, and other debris from surrounding terrestrial and wetland disturbances. This landscape-level accrual of materials provides invasive and expansive species with the resources they need to form monotypes (Tickner et al., 2001 ; Stohlgren et al., 1998 ; Zedler & Kercher, 2004 ). Invasive and expansive plant species often benefit from increased nutrients, successionally dominating and displacing more sensitive natives (Canavan et al., 2018 ; Green & Galatowitsch, 2002 ; Zedler & Kercher, 2005 ). Zedler and Kercher’s ( 2004 ) efficient use hypothesis proposes that invasive or expansive species use nutrients and light more efficiently than non-invasive species during succession. Houlahan and Findlay ( 2004 ) found that the non-native species were no more likely to dominate than native species and that dominants of both had similar adverse effects on species richness; indicating that dominants are generally of concern for producing monotypes during succession, regardless of their geographic origins (Houlahan & Findlay, 2004 ). Rising sea levels and storm surges due to climate change can lead to increased coastal flooding, especially with lack of natural coastal protection by functioning wetlands. These events can cause a breakdown in crucial services such as wastewater treatment. Coastal cities have historically placed wastewater treatment plants at low elevations near the coasts to reduce cost (Hummel et al., 2018 ). With the effects of climate change, wastewater treatment plants become more vulnerable to flooding, such that the number of people who would lose wastewater services could be more than five times as high as the number of people at risk of direct flooding due to sea-level rise (Hummel et al., 2018 ). Higher sea and storm surge levels can reduce the ability of wastewater pollution control plants to discharge sewer overflows and effluent, leading to increased flooding of sewers, streets, and basements (Major et al., 2011 ; Manuel, 2006 ). As sea-level rise caused by climate change threatens urban infrastructure like wastewater treatment facilities (Hummel et al., 2018 ), ecological engineering and nature-based adaptive solutions are being tested to make urban communities safer and more resilient. The importance of this ecological resilience to extreme weather events is even further highlighted by the continued growth of coastal population centers (U.S. Census Bureau, 2021 ). Coastal communities are now installing created wetlands for wastewater bioremediation, coastal area defense, and ecological habitat creation (Aydın Temel et al., 2018; Grebenshchykova et al., 2019 ; Gruber et al., 2008 ; Markus-Michalczyk et al., 2019 ). Constructed wetlands are a type of nature-based solution being implemented for bioremediation, as an ecological engineering alternative to traditional wastewater treatment, and can support a wide range of plants and wildlife (De Martis et al., 2016 ; Zhang et al., 2020 ). The current research on the ability of created wetlands to retain floristic diversity shows mixed results (De Martis et al., 2016 ; Saggaï et al., 2017 ). Some mitigation wetlands have been shown to provide more plant species diversity, richness, and evenness than natural reference wetlands, as well as improved bird habitats (Balcombe et al., 2005 ; Heaven et al., 2003 ). However, these authors also identify more species of lower conservation quality, including non-native dominants and pioneer species in mitigation wetlands, indications of disturbed habitat (Balcombe et al. 2005 ; Heaven et al. 2003 ). Ongoing study of vegetation dynamics within constructed wetlands is critical for understanding how the unique dynamics of a specific wetland play a role in its ability to retain plant species diversity. The continued ecosystem function of wetlands, including as coastal protection, is especially important in light of sea-level rise and increasing extreme weather events (Costanza et al. 2008 ; Zedler & Kercher, 2005 ). In 2015, the Oro Loma Sanitary District (OLSD) in San Lorenzo, California piloted a wastewater treatment approach, a horizontal levee that uses a low-grade slope (1:30, 1.9°) to allow native planting and protect adjacent land from storm surges. The Oro Loma Horizontal Levee (OLHL) is a multi-disciplinary prototype designed to evaluate how well a horizontal levee treats wastewater, buffers sea-level rise and flooding, and mitigates wetland habitat loss amid urban density (Okamoto, 2015; Taylor-Burns et al. 2025 ). Cecchetti et al. ( 2020 ) confirmed the levee’s ability to produce tertiary-treated effluent from secondary-treated wastewater. No previous researchers have studied successional change in plant assemblages in this created-wetland ecosystem. The objective of this research was to understand better how wetland plant communities in constructed treatment wetlands may change compositionally over time through succession and resist invasion or expansion of dominant species, despite receiving continuous subsurface nutrient enrichment. We characterize the 2020/2021 composition and species diversity of plants in wet meadow and riparian scrub assemblages on the OLHL ecotone slope and document the changes in composition and diversity over the five years following installation. We specifically explore how successional change in species diversity and relative species abundances differed between these two plant assemblages, and how fragmentation, and the sources and presence of key dominant expansive species affected community succession. Materials and Methods The Oro Loma Horizontal Levee (“levee”) is located at the Oro Loma Sanitary District (OLSD) treatment facility in in San Lorenzo, Alameda County, California (37.67°N by 122.16°W) on the San Francisco Bay (Fig. 1 ). The SF Bay Area has a Mediterranean climate with mean temperatures ranging from 10.3°C to 21.9°C. Average annual rainfall at the site is between 0 and 7.1 cm, occurring mostly in the winter months (NOAA National Centers for Environmental Information, 2021). This site and the surrounding area were tidal marsh and tidal flat habitat (Josselyn, 1983; San Francisco Estuary Institute [SFEI], 1998) until 1911, when the original water treatment facility was built. In 2015 and 2016, working with UC Berkeley researchers, the OLSD added a pilot project to evaluate whether planting native vegetation to form an ecotone slope on a horizontal levee, watered by secondary-treated water through distribution pipes from the adjacent treatment wetland, could serve as nature-based solution to remove further pollutants from the wastewater, protect the facility from flooding, and create native wetland habitat (Fig. 2 ). The horizontal levee was planted with a vegetated “ecotone slope”, (~ 0.7 ha) divided into 12 vertical cells (12 m x 46 m), separated by 2-m-wide clay berms (Save the Bay, 2017). Dr. Peter Baye worked with staff from Save the Bay, a local nonprofit organization, to model three vegetation suites after local native plant assemblages: swale-depression (swale-depression grade), wet meadow, and riparian scrub (uniform grade) (Jason Warner, General Manager, OLSD, personal communication, December 18, 2019; Save the Bay, 2017). The suites comprised vigorous or “weedy” native species, predicted by organization staff to compete effectively with and prevent establishment of volunteer and non-native invasive species (Donna Ball, personal communication, December 13, 2019; Save the Bay, 2017; Table 1). In wet meadow cells, Elymus triticoides , a native rhizomatous grass that can become weedy or invasive in some habitats (Young-Mathews & Winslow, 2010 ), was planted in the largest proportion, while riparian scrub cells featured Salix lasiolepis , a plant known for vigorous, fast growth, high productivity and efficient nutrient uptake (Kuzovkina & Quigley, 2005 ). The three swale-depression cells were planted adjacent to one another with fine topsoil. Three of six wet meadow cells were planted adjacent to one another in fine topsoil, while the other three were planted in coarse topsoil and interspersed with the three riparian scrub cells. The goals of the alternating plantings were to make the site bird-friendly by providing landscape-level vegetative structure (Jason Warner, General Manager, OLSD, personal communication, June 3, 2021). Each cell consisted of 15 horizontal planting grids (12 m x 3 m), repeated down the slope. Save the Bay staff members and volunteers collected, propagated, and planted all vegetation on the ecotone slope during November and December 2015 and January 2016 (Save the Bay, 2017). In 2017, staff members then planted the basin of the adjoining treatment wetland with cattail ( Typha spp.) and bulrush bulbs ( Schoenoplectus spp.) to enhance habitat value of the wetland (Fig. 1 ). Cattail was not planted on the ecotone slope, but the species reportedly encroached onto the slope after the plantings in the treatment wetland. By 2017, the entire site was also invaded by exotic jubatagrass ( Cortaderia jubata ) (Save the Bay, 2017). Study Design To contrast successional changes since installation for the wet meadow (WM) versus riparian scrub (R) assemblages on the ecotone slope, we first compare the initial percentage of each species planted in 2015/2016 with its relative percent cover in the field in 2020/2021 using proportions compiled across all 840 wet meadow and 380 riparian scrub quadrat samples (WM = 312 m 2 ; R = 141 m 2 ) Fig. 3 ). We assess potential effects of fragmentation on succession and invasion in the wet meadow assemblage by contrasting changes in percent cover across the 420 quadrats from the three contiguous (“buffered” or “BWM”) wet meadow cells with the 420 quadrats from the three wet meadow cells that are interspersed with riparian scrub (“fragmented” or “FWM”). We then evaluate how the mean per-quadrat diversity of planted wet meadow species changed through time in each of the four cell types. We describe likely sources of encroaching plant propagules in each assemblage and cell type with a focus on occurrences of a key invasive exotic species, Cortaderia jubata , and dominant encroaching species. Finally, we examine how presence of key dominant or invasive plant species, either individually or cumulatively, affects community diversity and individual percent cover of planted and volunteer species at the single quadrat level. Data Collection and Sampling In most cells, JF placed 10 stratified-random 0.3 m x 0.3 m PVC quadrats along each of fourteen 12-m transects distributed across eight of the horizontal planting grids for a total of 140 quadrats per cell (Fig. 4 ). In general, JF set two transects in six of the grids, but only one transect in the remaining two. In riparian cell 12, we skipped the transects in the top two grids, as they were impenetrable with dense vegetation, yielding 120 quadrats. JF positioned each quadrat using a vertical tape measure from the top edge of the cell and a horizontal transect tape measure from the nearest clay dividing berm. To measure percent cover accurately, JF marked each side of the quadrat with ten lines to denote 100 subdivisions. The quadrat was placed above the plants to be measured and below the horizontal transect tape. As needed, JF estimated the percent cover of S. lasiolepis canopy above the quadrat using a spherical densiometer (Forestry Suppliers Concave Model-A). Due to multiple canopy layers and bare ground, total percent cover for a quadrat could exceed or be less than 100%. Field data was collected during the fall and summer, as this was the best phenological period for plant identification, and plants were identified using planting lists, iNaturalist, and the Jepson Manual (Baldwin et al., 2012 ). To generate 2015/16 data values, quadrats were virtually sampled from the original planting plans using Python (version 3). Data Analysis To assess overall successional change, we first averaged the percent cover of each species over all quadrats when planted and in 2020/2021 for each of the cell types overall; WM, R, BWM, and FWM with a Texas Instrument-83 (TI-83) calculator. We also used a TI-83 calculator to calculate one-proportion z -tests to estimate the likelihood that the proportions of each species in a cell-type differed statistically between the two dates. We also calculated Simpson’s Reciprocal Diversity Index ( RDI ) in Microsoft Excel (version 16), using species richness and percent cover of each plant species (Tomascik & Sander, 1985 ; Onaindia et al., 2004 ; Oswalt et al., 2007 ), for the subset of quadrats in which any planted species survived to the 2020/2021 season, as the metric generates a null outcome for zero values. To assess changes in all planted species’ RDI since installation, we used paired t -tests (SPSS version 27) Because the data could not be normalized, we used a Mann-Whitney U test in SPSS to compare the change in the RDI’ s in the buffered and fragmented WM among three different plant community subsets: a) planted wet meadow species; b) any ecotone-slope-planted species (wet meadow, riparian scrub, or swale depression); and c) all plants found on the horizontal levee, including volunteer and exotic species. To assess the relative sources of propagules, encroaching or invading species were put into three categories: (a) species planted elsewhere on the ecotone slope, (b) species planted in the treatment wetland, and (c) volunteer species not planted in either the treatment wetland or the ecotone slope. We used two-proportion z -tests to contrast propagules sources in WM versus R and BWM versus FWM cells. For FWM, we used the more conservative one-sided test to reflect the greater likelihood of encroachment by riparian species. For the principal invasive exotic species we encountered, C. jubata , we used chi-square tests of independence in SPSS to compare presence/absence across quadrats in WM versus R and FWM versus BWM cells. To assess how the presence of S. lasiolepis , Typha , or both together affected planted species succession in the wet meadow assemblage, we compared RDI and total percent cover of wet meadow species in each quadrat between installation and the 2020/2021 field season using a Kruskal-Wallis test in SPSS. Since S. lasiolepis was already present in the riparian area, we did not assess its effect on the riparian assemblage. Results In 2020/2021, the dominant species on the ecotone slope were S. lasiolepis and Typha spp. These species both deposited thick layers of thatch. A majority of the Typha that was recorded was solely thatch material. Leaf litter from S. lasiolepis was found in most instances where live S. lasiolepis was recorded. Changes in Plant Community Parameters: Proportional Change in Species’ Cover Since Planting In the wet meadow, all species initially planted in 2015/2016 were still present in 2020/2021 (Table 2a). Proportions of Juncus balticus articus , Baccharis glutinosa , and Euthamia occidentalis increased compared to initial plantings ( z = 4.54, 5.07, 5.54, respectively, p < 0.001). All other wet meadow species decreased measurably through time ( z <- 2.85, p < 0.001), except for Carex praegracilis , whose apparent decline was minor enough that it was not statistically detectable ( p = 0.21). In the riparian scrub cells, proportions of Salix lasiolepis and Carex barbarae increased substantially by 2020/2021 ( z = 57.11, p < 0.001; z = 2.72, p = 0.006; Table 2b), and Rubus ursinus maintained its original planting proportions. All other species planted in the riparian scrub cells decreased through time ( z < -2.19, p < 0.001), including Cornus sericea and Sambucus nigra , which were no longer present by 2020/2021 on the ecotone slope. Every species planted in a wet meadow was found in greater proportion in the buffered (Table 2c) compared to the fragmented cells (Table 2d). Three wet meadow species, Ambrosia psilostachya , Symphyotricum chilense , and Lythrum californicum did not persist in any fragmented wet meadow samples. Changes in Plant Community Parameters: Changes in Species Diversity Simpson’s reciprocal diversity of planted species decreased substantially, especially in the riparian scrub assemblage, between the original installation and the 2020/2021 field season. For the wet meadow, the mean RDI dropped from 0.31 when planted to 0.19 ( t (650) = -9.14, p < 0.001; Figure 5a), and the riparian scrub planted species RDI dropped from 0.26 to just 0.11 in 2020/2021 ( t (378) = -10.08, p < 0.001; Figure 5b). For the buffered wet meadow cells, the planted RDI dropped from an initial mean of 0.30 to 0.21 (t (395) = -5.07, p < 0.001; Figure 5c), and the fragmented wet meadow fell even further, from a mean RDI of 0.32 to 0.14 (t (254) = -8.3, p < 0.001; Figure 5d). Interactions among species in Buffered and Fragmented Wet Meadow Cells Overall, the buffered WM cells supported higher median diversity of native species installed on the ecotone slope than the fragmented wet meadow cells, both in terms of the WM species diversity ( z (standardized U ) = 5.31, p < 0.001 ; Figure 6a) and overall diversity (WM, R, and swale-depression species) ( z (standardized U ) = 2.16 p = 0.031; Figure 6b). When volunteer and invasive species were included, however, the fragmented WM was more diverse than the buffered WM ( z (standardized U ) = -4.6, p < 0.001; Figure 6c). Sources of Encroaching and Invasive Species By 2020/2021, the FWM cells had much greater percent cover of species not planted in those cells than the BWM cells ( z < -20.74, p < 0.001; Figure 7a), predominately S. lasiolepis from riparian scrub cells and Typha from the treatment wetland. The fragmented cells also retained much lower percent cover of original wet meadow species than the buffered cells ( z = 32.56, p < 0.001) . Although fragmented and buffered WM cells did not differ in overall proportions of volunteer or exotic species ( z = -0.58, p = 0.95), the FWM also had more quadrats with C. jubata than the BWM (𝜒 2 (1) = 21.53, p 5.69, p < 0.001; Figure 7b). About 39.8% of the wet meadow area contained species from other cells, mostly comprising S. lasiolepis encroaching from riparian scrub cells. The riparian scrub quadrats had no detectable encroachment from wet meadow species, however C. jubata occurred more frequently in the riparian scrub assemblage compared to the wet meadow (𝜒 2 (1) = 4.51, p = 0.034; Figure 8). Effects of Salix lasiolepis , Typha on WM Diversity and Total Cover In the wet meadow assemblage, by 2020/2021, quadrats encroached with either S. lasiolepis , Typha spp. , or both had lower diversity (H(3) = 45.68, p<0.0001; Figure 9a) and lower total percent cover of the originally planted WM species (H(3) = 316.43, p<0.0001; Figure 9b). The effect of S. lasiolepis presence on total WM planted-species cover was significantly greater than Typha alone. Discussion This study documents a substantial reduction in plant diversity in the five years post-installation of an ecotone slope on a horizontal levee designed to protect a wastewater treatment facility on the San Francisco Bay. Both wet meadow and riparian scrub assemblages planted on the ecotone slope lost diversity over time, but the riparian scrub assemblage in particular became dominated by the hardy native Salix lasiolepis . The wet meadow plant assemblage was encroached by both S. lasiolepis , from interspersed riparian scrub assemblage, and Typha , from the treatment wetland. Our evidence suggests that fragmentation and dominance by species with invasive tendencies played central roles in native plant succession and led to greater invasion by the dominant exotic Cortaderia jubata , although the different soil types across these assemblages may have played a role in their succession. Our results support the idea that designs for nature-based solutions would benefit from incorporating larger habitat patch sizes, but that they may also require ongoing intervention and adaptation to limit effects of fragmentation, species invasion, and succession and achieve habitat creation goals. Natural wetland ecosystems rely on flooding and drought to maintain their biodiversity and ecological function (Middleton, 1999 ; Zedler, 2000 ). This ecotone slope contrasted two native wetland plant assemblages, wet meadow and riparian scrub, which are adapted to distinct natural hydrological disturbance regimes. Shallow water tables and soil saturation are characteristic of wet meadows, with soils remaining moist for much of the year (Barbour et al., 2007 ; Zentner et al., 2003 ). Riparian ecosystems tend to have more intense hydrological regimes, with hydrological disturbance and sediment deposition being important for maintaining riparian vegetative composition (Barbour et al., 2007 ; Tabacchi et al., 1998 ). Cells on the ecotone slope, in contrast, receive constant subsurface flow, but the topsoil was often dry during our survey period. Lack of a natural hydrologic disturbance regime to break dominance may have contributed to the riparian scrub assemblage’s overwhelming growth of S. lasiolepis , its loss of two planted trees, C. sericea and S. nigra , and reduction of most riparian understory species, helping explain why the riparian scrub assemblage lost more native diversity than the wet meadow. Although the ecotone slope’s hydrological regime was somewhat more like a wet meadow, historically wet meadows in the San Francisco Bay area are also seasonally flooded (Fox et al., 2015 ). Early successional ecosystems are susceptible to diversity loss and woody species proliferation in the absence of seasonal disturbance (Keddy & Rezicek, 1986, Greenberg et al., 2011 ; Williams et al., 1987 ). In our study, over five years the wet meadow assemblage transitioned from a grassland to a forb and shrubland. In 2012, Ratajczack et al. documented that woody species encroachment in grasslands reduces community species richness, and several authors have shown that Baccharis pilularis invasion completely changes the plant community and ecosystem function of grasslands (Williams et al., 1987 ; Zavaleta & Kettley, 2006 ). Many authors have argued that communities composed of species that vary in phenology, reproductive process, and ecological function resist invasion, particularly by functionally similar species (Byun, 2013; Fagúndez & Lema, 2019 ; Fried et al., 2015 ; Zedler, 2000 ). The riparian scrub community may have experienced substantially less Typha encroachment compared to the wet meadow due to inclusion of S. lasiolepis in the planting palette. Plumb et al., ( 2013 ) document considerable reduction of Typha biomass under increased shade and moisture of hardwood canopy. By that argument, light conditions in the wet meadow may have been more conducive to Typha establishment, persistence and survival than in the riparian scrub assemblage. Over twice as much Typha invaded the fragmented WM, however, despite it having much higher levels of S. lasiolepis than the buffered WM. Compared to larger habitat patches, fragments provide a disproportionate amount of edge, which is conducive to the introduction and establishment of species with invasive qualities (Cronk & Fuller, 1995 ). In this case, encroachment of S. lasiolepis , a riparian scrub assemblage species, into the fragmented wet meadow can be explained by the large amount of shared edge facilitating its movement. Greater Typha and C. jubata encroachment into fragmented versus buffered wet meadow is more puzzling, however, and suggests that encroaching S. lasiolepis may even have facilitated invasions of other species at lower densities, possibly by shading out smaller WM and other riparian species. Created urban wetlands that treat wastewater may be particularly vulnerable to domination by vegetative monotypes, due to the continuous input of nutrient-rich wastewater (Canavan et al., 2018 ; Green & Galatowitsch, 2002 ). Consistent with Zedler and Kercher’s ( 2004 ) efficient use hypothesis, Salix lasiolepis’ superior growth and productivity, more efficient nutrient uptake than competitors, and drought and salinity tolerance likely permitted it to withstand the conditions on the ecotone slope better and even directly suppress other planted species (Ericsson, 1981 ; Elowson, 1999 ; Frieswyk & Zedler, 2006 ; Kuzovkina & Quigley, 2005 ; Woo & Zedler, 2002 ). Unlike other species, S. lasiolepis often benefits from partial limb breaks as a means for lateral dispersal through epicormic shoots and adventitious roots. Using growth morphology as a dispersal mechanism allows it to outcompete neighboring plants (Boland 2024 ). Typha is wind pollinated and some species of Typha can have up to 420 million pollen grains per inflorescence, which can remain viable for weeks (Grace & Harrison 1986 ). Once established, Typha spp. form dense, nearly monotypic stands; it is often taller than the species it displaces; it uses nutrients efficiently; and it leaves behind an abundant amount of thatch that can suppress other species’ germination or growth (Larkin et al., 2012 ; Newman et al., 1996 ; Vaccaro et al., 2009 ). We find that abundance of the two dominant native wetland plants in our system, Salix lasiolepis and Typha spp. reduced plant community diversity and altered community structure where they invaded the wet meadow. Weiher & Keddy ( 1995 ) suggest that Typha litter can even act as a “filter,” causing extant plant communities to differ from the communities represented in the seed bank. The combined presence of Typha and Salix lasiolepis and layers of thatch in the fragmented wet meadow cells may have created a double encroachment pressure, resulting in the greater declines in diversity than in the buffered, which only faced encroachment from treatment wetland plants. Overall, although Typha proved to be an important expansive species, the native, planted, riparian species S. lasiolepis proved to have the greatest effect on ecosystem succession and diversity in the absence of natural hydrologic disturbance. The major non-native invasive threat to the wet meadow was Cordateria jubata . C. jubata has spread throughout the ecotone slope, although it has been actively managed by the OLSD (Personal communication, Jason Warner, General Manager, OLSD and David Sedlak, Environmental Engineering, U.C. Berkeley). C. jubata demonstrates rapid growth and resource use under high water and nitrogen availability conditions (Vourlitis & Kroon, 2013 ). It also produces copious seeds, allowing its populations to persist by creating strong and continuous propagule pressure that considerably increases the probability of further expansion (Lambrinos, 2008 ). The greater presence of C. jubata , in the riparian scrub and fragmented wet meadow cells may have resulted from the effects of fragmentation, including the loss of three planted species in the fragmented wet meadow, which could have left more niche availability for C. jubata to fill and colonize. In addition to abiotic disturbances, wetland ecosystems in California evolved for millennia with management, such as burning, harvesting, and tending, by indigenous peoples. Natural anthropogenic disturbance shaped the distribution and abundance of managed species (Hankins, 2013 ; Lightfoot & Lopez, 2013 ; Stevens, 2020 ), and the role indigenous management has played for millennia in maintaining biodiversity is well-documented (Berkes et al., 2000 ; Mistry & Bernardi, 2016 ; Stevens, 2020 ; Zedler & Stevens, 2018 ). Stevens ( 2020 ) found that indigenous gathering, tending, and cultivating of C. barbarae for basket weaving enhanced its distribution and abundance, and understory species, such as C. barbarae , often fail to colonize restored riparian forests without human support. Typha and Salix have also been harvested and used by native peoples worldwide for food, medicine, clothing, shelter, and other tools (Bates & Lee, 1990 ; Grace & Harrison, 1986 ; Liptay, 1988 ; Motivans & Apfelbaum, 1987 ; Prashith et al., 2017; Tawfeek et al., 2021 ). Through genocide, slavery, and disease, however, regular indigenous ecosystem management and tending in California abruptly declined with European colonization (Zedler & Stevens, 2018 ). Loss of harvesting and burning led riparian canopies to close and tule marshes to progress to impenetrable and senescent states. Interestingly, although C. barbarae in this system successionally declined in both fragmented and buffered wet meadow cells, the species expanded without intervention in the riparian scrub assemblage, reflecting its tolerance and higher survivability under low-light conditions from a S. lasiolepis canopy (Moore et al., 2011 ). This suggests that more understanding of interspecific interactions and effects of traditional management as a natural disturbance are needed to maintain habitat diversity and quality. Conclusions and Recommendations Our findings underscore the importance of nuanced application of nature-based solutions. In the absence of natural disturbance processes, such as seasonal overland water flow or scouring, fragmentation may drive constructed wetlands to progress to a successional state dominated by fewer species. In this horizontal levee system, plant assemblage and patch size both strongly influenced community invasibility, expansion of dominant natives, Typha and S. lasiolepis , and spread of non-native C. jubata . Future projects would benefit from planting larger patches with lower edge ratios to facilitate ecosystem resistance to invasion and diversity loss. The biological complexity of historic undamaged ecosystems usually informs restoration of natural disturbance regimes (Angelstam, 1998 ; Middleton, 1999 ; Odion & Sarr, 2007 ) or active management (Hobbs et al., 2007 ) to achieve a specific desired ecosystem or state. Constructed treatment wetlands designed to fulfill multiple goals (wastewater treatment, flood control, and native habitat creation) tend to be limited in the amount of hydrologic disturbance they can incorporate. Subsurface flow is important for removing contaminants, some projects’ primary goal, but overland flow, or at least thorough soil saturation, is important for maintaining wetland habitats on the ecotone slope. Previous authors find that natural hydrological processes are overlooked in constructed wetlands (Grimm & Köppel, 2019 ), and temporal and spatial regimes are mostly homogenized (Bockelmann et al., 2002 ). The final 2018 phase of this project removed most of the overland flow, eliminating the natural hydrological disturbance. In cases such as this, designing plant assemblages to resist invasion, possibly by installing later successional habitats with fewer, more competitive species, may reduce costs of collecting, propagating, and growing plant species while still meeting habitat goals, and retaining overland flow and incorporating anthropogenic disturbances like mowing may be practical to maintain species diversity (Zedler, 2000 ). Given the current loss of biodiversity and wetland habitat worldwide and in California, projects like this one are crucial to restore healthy, diverse urban ecosystems and make cities more livable and resilient for people, plants, and animals, especially in this era of global climate change (Matthies et al., 2017 ; Norton et al., 2016 ). Sea-level rise will only increase constraints on wetland habitat. We have shown that plant communities in projects such as this must be monitored and maintained to ensure they maintain the biodiversity needed to sustain critical habitat and ecological resilience, vibrant green spaces, and resilient urban ecosystems. Declarations Acknowledgements This research took place on the ancestral and unceded land of the Muwekma Ohlone. This land continues to be of great importance to the Muwekma Ohlone tribe. Indigenous stewardships practices have helped inform the lens through which we view our work and such knowledge was crucial to the management suggestions put forward in this paper. We thank Dr. Metha Klock and Dr. Anand of San Jose State University for their feedback through the initial development of this paper. We thank the Oro Loma Sanitary District and former general manager Jason Warner for their support and cooperation during the field portion of this study. We thank Jessie Olson and Donna Ball from Save the Bay for providing the initial background information necessary to perform this work. We also extend thanks to Angela Perantoni and Aidan Cecchetti from the Sedlak Lab at UC Berkeley for information regarding their experiments on the Oro Loma Horizontal Levee. We extend additional thanks to Anita Wah for statistical advice and Marquess Valdez for assistance with specific analyses. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Competing Interests The authors have no relevant financial or non-financial interests to disclose. Authors’ contributions Joia Fishman and Dr. Rachel O’Malley conceived the ideas and designed methodology; JF collected the data; JF and RM analyzed the data; JF wrote the first draft of the manuscript. Both authors contributed critically to the drafts and gave final approval for publication. The authors declare no competing interests. Data availability Upon publication, all data associated with this manuscript will be made publicly available in the Dryad digital repository. References Angelstam PK (1998) Maintaining and restoring biodiversity in European boreal forests by developing natural disturbance regimes. J Veg Sci 9(4):593–602. https://doi.org/10.2307/3237275 Aydin Temel F, Avci E, Ardali Y (2018) Full scale horizontal subsurface flow constructed wetlands to treat domestic wastewater by Juncus acutus and Cortaderia selloana . Int J Phytoremediation 20(3):264–273. https://doi.org/10.1080/15226514.2017.1374336 Balcombe CK, Anderson JT, Fortney RH, Rentch JS, Grafton WN, Kordek WS (2005) A comparison of plant communities in mitigation and reference wetlands in the mid-appalchians. Wetlands 25(1):130–142. https://doi-org.libaccess.sjlibrary .org/10.1672/0277-5212(2005)025[0130:ACOPCI]2.0.CO;2 Baldwin BG, Goldman DH, Keil DJ, Patterson R, Rosatti TJ, Wilken DH (eds) (2012) The Jepson manual: Vascular plants of California. University of California Press Barbour M, Keeler-Wolf T, Schoenherr AA (eds) (2007) Terrestrial vegetation of California. University of California Press Bates CD, Lee MJ (1990) Tradition and innovation: A basket history of the Indians of the Yosemite-Mono Lake area. Yosemite Association Berkes F, Colding J, Folke C (2000) Rediscovery of traditional ecological knowledge as adaptive management. Ecol Appl 10(5):1251–1262. https://doi.org/10.1890/1051-0761(2000)010 [1251:ROTEKA]2.0.CO;2 Bockelmann AC, Bakker JP, Neuhaus R, Lage J (2002) The relation between vegetation zonation, elevation and inundation frequency in a Wadden Sea salt marsh. Aquat Bot 73(3):211–221. https://doi.org/10.1016/S0304-3770(02)00022-0 Boland J (2024) The role of partial limb breaks in the growth and persistence of arroyo willow ( Salix lasiolepis ). Madroño 71(2):71–83. https://doi.org/10.3120/0024-9637-71.2.71 Byun C, de Blois S, Brisson J (2013) Plant functional group identity and diversity determine biotic resistance to invasion by an exotic grass. J Ecol 101(1):128–139. https://doi.org/10.1111/1365-2745.13419 Canavan K, Paterson ID, Lambertini C, Hill MP (2018) Expansive reed populations—alien invasion or disturbed wetlands? AoB Plants 10(2):ply014. https://doi.org/10.1093/aobpla/ply014 Cecchetti AR, Stiegler AN, Graham KE, Sedlak DL (2020) The horizontal levee: A multi-benefit nature-based treatment system that improves water quality and protects coastal levees from the effects of seal level rise. Water Res X 7. https://doi.org/10.1016/j.wroa.2020.100052 Costanza R, Pérez-Maqueo O, Luisa Martinez M, Sutton P, Anderson SJ, Mulder K (2008) The value of coastal wetlands for hurricane protection. Ambio, 37 (4). https://www.jstor.org/stable/25547893 Cronk QC, Fuller JL (1995) Plant invaders: The threat to natural ecosystems. Chapman and Hall De Martis G, Mulas B, Malavasi V, Marignani M (2016) Can artificial ecosystems enhance local biodiversity? The case of a constructed wetland in a Mediterranean urban context. Environ Manage 57(5):1088–1097. https://doi.org/10.1007/s00267-016-0668-4 Duarte CM, Losada IJ, Hendriks IE, Mazarrasa I, Marbà N (2013) The role of coastal plant communities for climate change mitigation and adaptation. Nature 3(11):961–968. https://doi.org/10.1038/nclimate1970 Elowson S (1999) Willow as a vegetation filter for cleaning of polluted drainage water from agricultural land. Biomass Bioenergy 16:281–290. https://doi.org/10.1016/S0961-9534(98)00087-7 Ericsson T (1981) Growth and nutrition in three Salix clones grown in low conductivity solutions. Physiol Plant 52:239–244. https://doi.org/10.1111/j.1399-3054.1981.tb08499.x Fagúndez J, Lema M (2019) A competition experiment of an invasive alien grass and two native species: Are functionally similar species better competitors? Biol Invasions 21(12):3619–3631. https://doi.org/10.1007/s10530-019-02073-y Fluet-Chouinard E, Stocker BD, Zhang Z et al (2023) Extensive global wetland loss over the past three centuries. Nature 614:281–286. https://doi.org/10.1038/s41586-022-05572-6 Fox P, Hutton PH, Howes DJ, Draper AJ, Sears L (2015) Reconstructing the natural hydrology of the San Francisco Bay–Delta watershed. Hydrol Earth Syst Sci 19(10):4257–4274. https://doi.org/10.5194/hess-19-4257-2015 Fried G, Belaud A, Chauvel B (2015) Ecology and impact of an emerging invasive species in France: Western ragweed ( Ambrosia psilostachya DC). Revue d’Ecologie (Terre et Vie) 70:53–67. http://hdl.handle.net/2042/57884 Frieswyk CB, Zedler JB (2006) Do seed banks confer resilience to coastal wetlands invaded by Typha x glauca? Botany 84(12):1883–1892. https://doi.org/10.1139/B06-100 Grace JB, Harrison JS (1986) The biology of Canadian weeds.: 73. Typha latifolia L., Typha angustifolia L. and Typha x glauca Godr. Can J Plant Sci 66(2):361–379. https://doi.org/10.4141/cjps86-051 Grebenshchykova Z, Frédette C, Chazarenc F, Comeau Y, Brisson J (2019) Establishment and potential use of woody species in treatment wetlands. Int J Phytoremediation 22(3):295–304. https://doi.org/10.1080/15226514.2019.1658712 Green EK, Galatowitsch SM (2002) Effects of Phalaris arundinacea and Nitrate-N addition on the establishment of wetland. J Appl Ecol 39(1):134–144. https://doi.org/10.1046/j.1365-2664.2002.00702.x Greenberg CH, Collins B, Thompson FR, McNab WH (2011) Introduction: What are early successional habitats, why are they important, and how can they be sustained? In Sustaining young forest communities (pp. 1–10). Springer Dordrecht. https://link.springer.com/chapter/ 10.1007/978-94-007-1620-9_1 Grimm M, Köppel J (2019) Biodiversity offset program design and implementation. Sustainability 11(24):6903. https://doi.org/10.3390/su11246903 Gruber H, Wiessner A, Kuschk P, Kaestner M, Appenroth KJ (2008) Physiological responses of Juncus effusus (rush) to chromium and relevance for wastewater treatment in constructed wetlands. Int J Phytoremediation 10(2):79–90. https://doi.org/10.1080/15226510801913306 Hankins DL (2013) The effects of indigenous prescribed fire on riparian vegetation in central California. Ecol Processes 2(1):1–9. https://doi.org/10.1186/2192-1709-2-24 Heaven JB, Gross FE, Gannon AT (2003) Vegetation comparison of a natural and a created emergent marsh wetland. Southeast Nat 2(2):195–206. https://doi.org/10.1656/1528-7092 (2003)002[0195:VCOANA]2.0.CO;2 Hobbs RJ, Jentsch A, Temperton VM (2007) Restoration as a process of assembly and succession mediated by disturbance. In Linking restoration and ecological succession (pp. 150–167). Springer. https://link.springer.com/chapter/ 10.1007/978-0-387-35303-6_7 Houlahan JE, Findlay CS (2004) Effect of invasive plant species on temperate wetland plant diversity. Conserv Biol 18(4):1132–1138. https://doi.org/10.1111/j.1523-1739.2004.00391.x Hummel MA, Berry MS, Stacey MT (2018) Sea level rise impacts on wastewater treatment systems along the U.S. coasts. Earths Future 6(4):622–633. http://dx.doi.org/10.1002/2017EF000805 Keddy PA, Reznicek AA (1986) Great Lakes vegetation dynamics: The role of fluctuating water levels and buried seeds. J Great Lakes Res 12(1):25–36. https://doi.org/10.1016/S0380-1330(86)71697-3 Kuzovkina YA, Quigley MF (2005) Willow beyond wetlands: Uses of Salix l . species for environmental projects. Water Air Soil Pollut 162:183–204. https://doi.org/10.1007/s11270-005-6272-5 Lambrinos JG (2008) The impact of the invasive alien grass Cortaderia jubata (Lemoine) Stapf on an endangered Mediterranean-type shrubland in California. Divers Distrib 6(5):217–231. https://doi.org/10.1046/J.1472-4642.2000.00086.X Larkin DJ, Freyman MJ, Lishawa SC, Geddes P, Tuchman NC (2012) Mechanisms of dominance by the invasive hybrid cattail Typha 3 glauca. Biol Invasions 14(1):65–77. https://doi.org/10.1007/s10530-011-0059-y Lightfoot KG, Lopez V (2013) The study of indigenous management practices in California: An introduction. Calif Archaeol 5(2):209–219. https://doi.org/10.1179/1947461X13Z.00000000011 Liptay A (1988) Typha: Review of historical use and growth and nutrition. In I International symposium on diversification of vegetable crops 242 (pp. 231–238). https://doi.org/10.17660/ActaHortic.1989.242.31 Major DC, Omojola A, Dettinger M, Hanson RT, Sanchez-Rodriguez R (2011) Climate change, water, and wastewater in cities. In Climate change and cities: First assessment report of the urban climate change research network (pp. 113–144). Cambridge University Press. https://uccrn.ei.columbia.edu/sites/default/files/content/docs/ARC3.1/ARC3-Chapter-5.pdf Manuel J (2006) In Katrina’s wake. Environ Health Perspect 114(1). https://doi.org/10.1289/ehp.114-a32 Markus-Michalczyk H, Zhu Z, Bouma TJ (2019) Morphological and biomechanical responses of floodplain willows to tidal flooding and salinity. Freshw Biol 64(5):913–925. https://doi.org/10.1111/fwb.13273 Matthies SA, Rueter S, Schaarschmidt F, Prasse R (2017) Determinants of species richness within and across taxonomic groups in urban green spaces. Urban Ecosyst 20(4):897–909. https://doi.org/10.1007/s11252-017-0642-9 Middleton BA (1999) Wetland restoration, flood pulsing, and disturbance dynamics. John Wiley & Sons, Inc. Mistry J, Bernardi A (2016) Bridging indigenous and scientific knowledge. Science 352(6291):1274–1275. http://dx.doi.org/doi:10.1126/science.aaf1160 Moore PL, Holl KD, Wood DM (2011) Strategies for restoring native riparian understory plants along the Sacramento River: Timing, shade, non-native control, and planting method. San Francisco Estuary Watershed Sci 9(2). https://doi.org/10.15447/sfews.2014v9iss2art1 Motivans K, Apfelbaum S (1987) Element stewardship abstract for Typha spp . The Nature Conservancy. https://doi.org/10.16/0890037X(2000)014[0446:CCTLL] 2.0.CO;2 Newman S, Grace JB, Koebel JW (1996) Effects of nutrients and hydroperiod on Typha , Cladium , and Eleocharis : Implications for everglades restoration. Ecol Appl 6(3):774–783. https://doi.org/10.2307/2269482 Norton BA, Evans KL, Warren PH (2016) Urban biodiversity and landscape ecology: Patterns, processes and planning. Curr Landsc Ecol Rep 1(4):178–192. https://doi.org/10.1007/s40823-016-0018-5 Odion DC, Sarr DA (2007) Managing disturbance regimes to maintain biological diversity in forested ecosystems of the Pacific Northwest. For Ecol Manag 246(1):57–65. https://doi.org/10.1016/j.foreco.2007.03.050 Onaindia M, Dominguez I, Albizu I, Garbisu C, Amezaga I (2004) Vegetation diversity and vertical structure as indicators of forest disturbance. For Ecol Manag 195(3):341–354. https://doi.org/10.1016/j.foreco.2004.02.059 Oswalt CM, Oswalt SN, Clatterbuck WK (2007) Effects of Microstegium vimineum (Trin.) A. Camus on native woody species density and diversity in a productive mixed-hardwood forest in Tennessee. Forest Ecology and Management , 242 (2–3), 727–732. https://doi.org/10.1016/j.foreco.2007.02.008 Plumb P, Day SD, Wynn-Thompson TM, Seiler JR (2013) Relationship between woody plant colonization and Typha L. Encroachment in stormwater detention basins. Environ Manage 52:861–876. https://doi.org/10.1007/s00267-013-0137-2 Prashith Kekuda T, Vinayaka K, Raghavendra H (2017) Ethnobotanical uses, phytochemistry and biological activities of Salix tetrasperma roxb. (Salicaceae)-A review. Journal of Medicinal Plants Studies , 5 (5), 201–206. https://www.plantsjournal.com/archives/? year = 2017&vol = 5&issue = 5∂ = C&ArticleId = 703 Ratajczak Z, Nippert JB, Collins SL (2012) Woody encroachment decreases diversity across North American grasslands and savannas. Ecology 93(4):697–703. https://doi.org/10.1890/11-1199.1 Saggaï MM, Ainouche A, Nelson M, Cattin F, Amrani E, A (2017) Long-term investigation of constructed wetland wastewater treatment and reuse: Selection of adapted plant species for metaremediation. J Environ Manage 201:120–128. https://doi.org/10.1016/j.jenvman.2017.06.040 Stevens ML (2020) Eco-cultural restoration of riparian wetlands in California: Case study of white root (Carex barbarae Dewey; Cyperaceae). Wetlands 40(6):2461–2475. https://doi.org/10.1007/s13157-020-01323-3 Stohlgren TJ, Bull KA, Otsuki Y, Villa CA, Lee M (1998) Riparian zones as havens for exotic plant species in the central grasslands. Plant Ecol 138(1):113–125. https://doi.org/10.1023/A:1009764909413 Tabacchi E, Correll DL, Hauer R, Pinay G, Planty-Tabacchi AM, Wissmar RC (1998) Development, maintenance, and role of riparian vegetation in the river landscape. Freshw Biol 40(3):497–516. https://doi-org.libaccess.sjlibrary .org/10.1046/j.1365-2427.1998.00381.x Tawfeek N, Mahmoud MF, Hamdan DI, Sobeh M, Farrag N, Wink M, El-Shazly AM (2021) Phytochemistry, pharmacology and medicinal uses of plants of the genus Salix: An updated review. Front Pharmacol 50. https://doi.org/10.3389/fphar.2021.593856 Taylor-Burns R, Reguero BG, Barnard PL et al (2025) Nature-based solutions extend the lifespan of a regional levee system under climate change. Sci Rep 15:16218. https://doi.org/10.1038/s41598-025-99762-7 Tickner DP, Angold PG, Gurnell AM, Mountford JO (2001) Riparian plant invasions: Hydrogeomorphological control and ecological impacts. Prog Phys Geogr 25(1):22–52. https://doi.org/10.1177%2F030913330102500102 Tomascik T, Sander F (1985) Effects of eutrophication on reef-building corals. Mar Biol 87(2):143–155. https://doi.org/10.1007/BF00539422 U.S. Census Bureau (2021) Emergency management coastal areas . Census.gov. https://www.census.gov/topics/preparedness/about/coastal-areas.html Vaccaro LE, Bedford BL, Johnston CA (2009) Litter accumulation promotes dominance of invasive species of cattails ( Typha spp.) in Lake Ontario wetlands. Wetlands 2009 29(3):1036–1048. https://doi.org/10.1672/08-28.1 Vourlitis GL, Kroon JL (2013) Growth and resource use of the invasive grass, Pampasgrass (Cortaderia selloana), in response to nitrogen and water availability. Weed Sci 61(1):117–125. https://doi.org/10.1614/WS-D-11-00220.1 Weiher E, Keddy PA (1995) The assembly of experimental wetland plant communities. Oikos 323–335. https://doi.org/10.2307/3545956 Williams K, Hobbs RJ, Hamburg SP (1987) Invasion of an annual grassland in Northern California by Baccharis pilularis ssp. consanguinea . Oecologia 1987 , 72 (3), 461–465. https://doi.org/10.1007/BF00377580 Woo I, Zedler JB (2002) Can nutrients alone shift a sedge meadow towards dominance by the invasive Typha × glauca ? Wetlands 22(3):509–521. https://doi.org/10.1672/0277-5212( 2002)022[0509:CNASAS]2.0.CO;2 Young-Mathews A, Winslow SR (2010) Plant guide for beardless wildrye (Leymus triticoides). USDA-Natural Resources Conservation Service. https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/capmcpg9969.pdf Plant Materials Center Zavaleta ES, Kettley LS (2006) Ecosystem change along a woody invasion chronosequence in a California grassland. J Arid Environ 66(2):290–306. https://doi.org/10.1016/j.jaridenv.2005.11.008 Zedler JB (2000) Progress in wetland restoration ecology. Tree 15(10):402–407. https://doi.org/10.1016/S0169-5347(00)01959-5 Zedler JB (2004) Compensating for wetland losses in the United States. Ibis 146:92–100 Zedler JB, Kercher S (2004) Causes and consequences of invasive plants in wetlands: Opportunities, opportunists, and outcomes. CRC Crit Rev Plant Sci 23(5):431–452. https://doi.org/10.1080/07352680490514673 Zedler JB, Kercher S (2005) Wetland resources: Status, trends, ecosystem services, and restorability. Annu Rev Environ Resour 30(1):39–74. https://doi.org/10.1146/annurev.energy.30.050504.144248 Zedler JB, Stevens ML (2018) Western and traditional ecological knowledge in ecocultural restoration. San Francisco Estuary Watershed Sci 16(3). https://doi.org/10.15447/sfews.2018v16iss3art2 Zentner J, Glaspy J, Schenk D (2003) Wetland and riparian woodland restoration costs. Ecol Restor 21(3):166–173. https://www.jstor.org/stable/43440447 Zhang C, Wen L, Wang Y, Liu C, Zhou Y, Lei G (2020) Can constructed wetlands be wildlife refuges? A review of their potential biodiversity conservation value. Sustainability 12(4):1442. https://doi.org/10.3390/su12041442 Tables Tables 1 and 2 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Tables.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8139631","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":553717870,"identity":"cfdfaccd-e1ab-4857-a883-1a8689c5466f","order_by":0,"name":"Joia Fishman","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA60lEQVRIiWNgGAWjYBACxgbGBoYKA4YEEPsBkODhI0rLGYgWZgOQFjairDrDANbCJgHiENTC3N7c+OFAQV2ebvvZY5Vfc+xk2BiYHz66gc9hPQebJQ4YHC42O5OXdlt2WzLQYWzGxjn4tMxIbJD+YHAgcduBHLPbktuYgVp42KQJaGn+ccCgLnHb+TdmxZLb6onS0gZ0GHPiths5Zowftx0mQkvPwTYLoF+AWt4YSzNuO87DxkzAL4bt7Y9vHPgDcliO4cef26rt+dmbHz7Gq6UBicPMAybxKAcBeRRX/iCgehSMglEwCkYmAADmEE5pp7K/9wAAAABJRU5ErkJggg==","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Joia","middleName":"","lastName":"Fishman","suffix":""},{"id":553717872,"identity":"3ea6e754-1589-4ff8-accf-7e8c544c469c","order_by":1,"name":"Rachel O'Malley","email":"","orcid":"","institution":"San Jose State University","correspondingAuthor":false,"prefix":"","firstName":"Rachel","middleName":"","lastName":"O'Malley","suffix":""}],"badges":[],"createdAt":"2025-11-18 01:08:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8139631/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8139631/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97664637,"identity":"e740bc01-3569-47f3-8322-bc336f7a7ee2","added_by":"auto","created_at":"2025-12-08 09:11:59","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8666735,"visible":true,"origin":"","legend":"","description":"","filename":"FragmentationDrivesDominantPlantEncroachmentonaHorizontalWastewaterTreatmentLevee.docx","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/249eddcc6c80ddcfcea68d43.docx"},{"id":97377437,"identity":"d46416fc-2112-479c-8c77-a800eb804645","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5645,"visible":true,"origin":"","legend":"","description":"","filename":"a19ff74ee1da40f0aa50c19d14856fb5.json","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/f28f87f736e990be618ac33a.json"},{"id":97664505,"identity":"17eef6c8-18e6-444e-ae46-79abf7f7b0a2","added_by":"auto","created_at":"2025-12-08 09:07:05","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":178045,"visible":true,"origin":"","legend":"","description":"","filename":"a19ff74ee1da40f0aa50c19d14856fb51enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/46120c1d12e40fad76d31965.xml"},{"id":97664557,"identity":"86d2413f-55c5-4920-897c-8f16c5ba46d8","added_by":"auto","created_at":"2025-12-08 09:09:58","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":147088,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/690aec609ea977a490315c9b.png"},{"id":97664597,"identity":"6d1a0a65-1bfa-43c1-8ba0-95605f9fdab7","added_by":"auto","created_at":"2025-12-08 09:11:14","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":105821,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/9b4ed23978dd0f0d035a02f2.png"},{"id":97377451,"identity":"7db13ef2-ff2e-4253-8ea8-7e39bed0717f","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30803,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/bd5636900d2a8e3286cfb804.png"},{"id":97377448,"identity":"c11ec965-e739-48bc-b547-ec73e4c5611b","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":78514,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/99b9c4fe79fe19319ce2bea8.png"},{"id":97664705,"identity":"7c946d9c-c649-49ea-9824-6b62f5e14075","added_by":"auto","created_at":"2025-12-08 09:13:16","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":32099,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/2cb10339605ea6f8ab9cf507.png"},{"id":97377452,"identity":"4a582ced-3972-4477-942f-07f43671f862","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13381,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/2317d77af213a77e803638b6.png"},{"id":97664858,"identity":"971d0870-0e35-4a37-9fc8-5771f501320d","added_by":"auto","created_at":"2025-12-08 09:15:07","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":33735,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/67259304aeb343860c1c812a.png"},{"id":97665010,"identity":"c5b2b1d2-58dc-4099-a36e-80ad51fa11cb","added_by":"auto","created_at":"2025-12-08 09:15:52","extension":"png","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":24887,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/a0ce5d00979a244bb636c13e.png"},{"id":97665497,"identity":"6b6e8896-d2ac-4363-8252-ada9210b027f","added_by":"auto","created_at":"2025-12-08 09:18:43","extension":"png","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":16394,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/5b27dfa830b4d410274713d7.png"},{"id":97377455,"identity":"ad44f79e-0f4d-4192-922f-597aee4fbbdf","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"xml","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":176241,"visible":true,"origin":"","legend":"","description":"","filename":"a19ff74ee1da40f0aa50c19d14856fb51structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/d288b83b1dc083ce138a6e18.xml"},{"id":97377457,"identity":"5b70964f-6d1e-49f4-a843-511c7994fa70","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"html","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":190543,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/5e8f681d6600ccd396b7e2f3.html"},{"id":97377434,"identity":"bac89ad1-be3c-429f-82e6-d0e9f9956ad2","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":742303,"visible":true,"origin":"","legend":"\u003cp\u003eTreatment wetland and ecotone slope at the Oro Loma Sanitary District in San Lorenzo, California (Adapted from Google Earth [2020])\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/f657ef1995a2696a22bafd6d.png"},{"id":97665499,"identity":"65e67fcc-0567-48ed-be34-13c52d4232e5","added_by":"auto","created_at":"2025-12-08 09:18:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":628505,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship of the treatment wetland to the ecotone slope showing twelve vertical cells with planting grid design. B = buffered wet meadow cells, F = fragmented wet meadow cells, and R = riparian scrub cells. (Adapted from Save the Bay, 2017; Environmental Science Associates [ESA] planning documents)\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/b5712b8c1d72ddc43b3be9b0.png"},{"id":97377438,"identity":"7844fefe-5199-4824-844a-30b0f84db67a","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":203144,"visible":true,"origin":"","legend":"\u003cp\u003eStudy Design. To estimate the 2015/16 percent cover, a Python data processing script was used to randomly sample quadrats from original planting documents. In 2020/21 percent cover was measured in the same quadrats in the field\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/04487db31907f9d327d9588e.png"},{"id":97377435,"identity":"f9a0a517-45d6-44e5-b278-f7435fc08eea","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":509790,"visible":true,"origin":"","legend":"\u003cp\u003eSampling scheme. Adapted from ESA planning documents. BWM = Buffered Wet Meadow, FWM = Fragmented Wet Meadow, R = Riparian. *Grids 3 and 6 only had 1 transect each. Yellow belts delineate sampled areas\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/52e78e617cdd1f8de8de538e.png"},{"id":97377441,"identity":"a406cd3c-b28e-4277-ae65-cdbef51d9fa2","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":185301,"visible":true,"origin":"","legend":"\u003cp\u003eChange in Simpson’s Reciprocal Diversity for planted species on the ecotone slope from installation in 2015/2016 to 2020/2021 in a) wet meadow (n = 651), b) riparian scrub habitat (n = 379), c) buffered wet meadow (n = 396), and d) fragmented wet meadow (n = 255) plant assemblages. Error bars represent a 95% confidence interval around the mean.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/03ce85654f93c63c29306d42.png"},{"id":97377446,"identity":"46fb016a-9639-45ab-a291-52abebe1c0af","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":50893,"visible":true,"origin":"","legend":"\u003cp\u003eDiversity of the buffered versus fragmented WM a) planted wet meadow species (buffered, n = 396, fragmented, n = 255), b) all species installed on the ecotone slope (buffered, n = 398, fragmented, n = 408), c) all plant species including volunteer and invasive species (buffered, n = 420, fragmented, n = 420). All differences are significant, p\u0026lt;0.5\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/232055583853f8ec0539e7ef.png"},{"id":97664537,"identity":"176b1401-f39f-4626-8bf6-866b3119349c","added_by":"auto","created_at":"2025-12-08 09:09:16","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":162345,"visible":true,"origin":"","legend":"\u003cp\u003ePropagule source for (a) wet meadow and riparian scrub cells and (b) buffered and fragmented wet meadow. The y-axis goes over 100% due to overlapping canopy cover.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/c2d7b81de30fd456d723646f.png"},{"id":97665119,"identity":"ed7cbc9a-7a3f-4f55-9241-08968070f576","added_by":"auto","created_at":"2025-12-08 09:16:39","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":57550,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eCortaderia jubata\u003c/em\u003eoccurrence in wet meadow, riparian scrub, buffered wet meadow, and fragmented wet meadow quadrats.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/18fb7714fd9a38d6f8008f8c.png"},{"id":97377444,"identity":"535b11b8-5580-4fea-baaa-70d7b711724a","added_by":"auto","created_at":"2025-12-03 16:59:17","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":60934,"visible":true,"origin":"","legend":"\u003cp\u003eThe relationship between the presence of two dominant species on planted wet meadow species’ a) diversity (n = 651) and b) cover (n = 840). Bars with different letters differ significantly, p \u0026lt; 0.001\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/e6d200a77f5f19eb6f43da63.png"},{"id":99789779,"identity":"01fdc6bd-58b7-4c97-988d-7f7a4e914c3f","added_by":"auto","created_at":"2026-01-08 12:50:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3538132,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/0fc312b6-34a5-476b-b7fb-9a17d38e851f.pdf"},{"id":97665018,"identity":"bf05c4e9-ba67-47ed-a890-bc65e07c59f2","added_by":"auto","created_at":"2025-12-08 09:15:52","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":21564,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8139631/v1/3fcfbefbcb24ddea1eee2e5f.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Fragmentation Drives Dominant Plant Encroachment on a Horizontal Wastewater Treatment Levee","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCalifornia has lost about 80% of its historical wetlands to alteration, draining, or filling (Zedler \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Worldwide, 21% of wetlands have been lost since the 1700s (Fluet-Chouinard et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Wetlands provide habitat for flora and fauna, protect coasts from sea-level rise and flooding, improve water quality, and serve as important ecosystems for carbon sequestration (Zedler \u0026amp; Kercher, \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). In contrast, engineered protections from sea-level rise, such as sea walls, generally harm biodiversity (Duarte et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Costanza et al. (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) calculated that, as of 2008, coastal wetlands provided \u003cspan\u003e$\u003c/span\u003e23.3\u0026nbsp;billion (U.S.) per year in storm protection services alone, as well as crucial habitat for sensitive species.\u003c/p\u003e\u003cp\u003eReestablishing lost wetland biodiversity through restoration can be difficult. Wetlands are particularly susceptible to the formation of vegetative monotypes, because they are landscape sinks (Zedler \u0026amp; Kercher, \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2004\u003c/span\u003e), often occurring in low-lying areas that accumulate nutrients, propagules, sediments, and other debris from surrounding terrestrial and wetland disturbances. This landscape-level accrual of materials provides invasive and expansive species with the resources they need to form monotypes (Tickner et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Stohlgren et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Zedler \u0026amp; Kercher, \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Invasive and expansive plant species often benefit from increased nutrients, successionally dominating and displacing more sensitive natives (Canavan et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Green \u0026amp; Galatowitsch, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Zedler \u0026amp; Kercher, \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). Zedler and Kercher\u0026rsquo;s (\u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2004\u003c/span\u003e) efficient use hypothesis proposes that invasive or expansive species use nutrients and light more efficiently than non-invasive species during succession. Houlahan and Findlay (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2004\u003c/span\u003e) found that the non-native species were no more likely to dominate than native species and that dominants of both had similar adverse effects on species richness; indicating that dominants are generally of concern for producing monotypes during succession, regardless of their geographic origins (Houlahan \u0026amp; Findlay, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eRising sea levels and storm surges due to climate change can lead to increased coastal flooding, especially with lack of natural coastal protection by functioning wetlands. These events can cause a breakdown in crucial services such as wastewater treatment. Coastal cities have historically placed wastewater treatment plants at low elevations near the coasts to reduce cost (Hummel et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). With the effects of climate change, wastewater treatment plants become more vulnerable to flooding, such that the number of people who would lose wastewater services could be more than five times as high as the number of people at risk of direct flooding due to sea-level rise (Hummel et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Higher sea and storm surge levels can reduce the ability of wastewater pollution control plants to discharge sewer overflows and effluent, leading to increased flooding of sewers, streets, and basements (Major et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Manuel, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAs sea-level rise caused by climate change threatens urban infrastructure like wastewater treatment facilities (Hummel et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), ecological engineering and nature-based adaptive solutions are being tested to make urban communities safer and more resilient. The importance of this ecological resilience to extreme weather events is even further highlighted by the continued growth of coastal population centers (U.S. Census Bureau, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Coastal communities are now installing created wetlands for wastewater bioremediation, coastal area defense, and ecological habitat creation (Aydın Temel et al., 2018; Grebenshchykova et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Gruber et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Markus-Michalczyk et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Constructed wetlands are a type of nature-based solution being implemented for bioremediation, as an ecological engineering alternative to traditional wastewater treatment, and can support a wide range of plants and wildlife (De Martis et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhang et al., \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The current research on the ability of created wetlands to retain floristic diversity shows mixed results (De Martis et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Sagga\u0026iuml; et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Some mitigation wetlands have been shown to provide more plant species diversity, richness, and evenness than natural reference wetlands, as well as improved bird habitats (Balcombe et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Heaven et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). However, these authors also identify more species of lower conservation quality, including non-native dominants and pioneer species in mitigation wetlands, indications of disturbed habitat (Balcombe et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Heaven et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Ongoing study of vegetation dynamics within constructed wetlands is critical for understanding how the unique dynamics of a specific wetland play a role in its ability to retain plant species diversity. The continued ecosystem function of wetlands, including as coastal protection, is especially important in light of sea-level rise and increasing extreme weather events (Costanza et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zedler \u0026amp; Kercher, \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn 2015, the Oro Loma Sanitary District (OLSD) in San Lorenzo, California piloted a wastewater treatment approach, a horizontal levee that uses a low-grade slope (1:30, 1.9\u0026deg;) to allow native planting and protect adjacent land from storm surges. The Oro Loma Horizontal Levee (OLHL) is a multi-disciplinary prototype designed to evaluate how well a horizontal levee treats wastewater, buffers sea-level rise and flooding, and mitigates wetland habitat loss amid urban density (Okamoto, 2015; Taylor-Burns et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Cecchetti et al. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) confirmed the levee\u0026rsquo;s ability to produce tertiary-treated effluent from secondary-treated wastewater. No previous researchers have studied successional change in plant assemblages in this created-wetland ecosystem.\u003c/p\u003e\u003cp\u003eThe objective of this research was to understand better how wetland plant communities in constructed treatment wetlands may change compositionally over time through succession and resist invasion or expansion of dominant species, despite receiving continuous subsurface nutrient enrichment. We characterize the 2020/2021 composition and species diversity of plants in wet meadow and riparian scrub assemblages on the OLHL ecotone slope and document the changes in composition and diversity over the five years following installation. We specifically explore how successional change in species diversity and relative species abundances differed between these two plant assemblages, and how fragmentation, and the sources and presence of key dominant expansive species affected community succession.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThe Oro Loma Horizontal Levee (\u0026ldquo;levee\u0026rdquo;) is located at the Oro Loma Sanitary District (OLSD) treatment facility in in San Lorenzo, Alameda County, California (37.67\u0026deg;N by 122.16\u0026deg;W) on the San Francisco Bay (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eThe SF Bay Area has a Mediterranean climate with mean temperatures ranging from 10.3\u0026deg;C to 21.9\u0026deg;C. Average annual rainfall at the site is between 0 and 7.1 cm, occurring mostly in the winter months (NOAA National Centers for Environmental Information, 2021). This site and the surrounding area were tidal marsh and tidal flat habitat (Josselyn, 1983; San Francisco Estuary Institute [SFEI], 1998) until 1911, when the original water treatment facility was built. In 2015 and 2016, working with UC Berkeley researchers, the OLSD added a pilot project to evaluate whether planting native vegetation to form an ecotone slope on a horizontal levee, watered by secondary-treated water through distribution pipes from the adjacent treatment wetland, could serve as nature-based solution to remove further pollutants from the wastewater, protect the facility from flooding, and create native wetland habitat (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eThe horizontal levee was planted with a vegetated \u0026ldquo;ecotone slope\u0026rdquo;, (~\u0026thinsp;0.7 ha) divided into 12 vertical cells (12 m x 46 m), separated by 2-m-wide clay berms (Save the Bay, 2017). Dr. Peter Baye worked with staff from Save the Bay, a local nonprofit organization, to model three vegetation suites after local native plant assemblages: swale-depression (swale-depression grade), wet meadow, and riparian scrub (uniform grade) (Jason Warner, General Manager, OLSD, personal communication, December 18, 2019; Save the Bay, 2017). The suites comprised vigorous or \u0026ldquo;weedy\u0026rdquo; native species, predicted by organization staff to compete effectively with and prevent establishment of volunteer and non-native invasive species (Donna Ball, personal communication, December 13, 2019; Save the Bay, 2017; Table 1). In wet meadow cells, \u003cem\u003eElymus triticoides\u003c/em\u003e, a native rhizomatous grass that can become weedy or invasive in some habitats (Young-Mathews \u0026amp; Winslow, \u003cspan class=\"CitationRef\"\u003e2010\u003c/span\u003e), was planted in the largest proportion, while riparian scrub cells featured \u003cem\u003eSalix lasiolepis\u003c/em\u003e, a plant known for vigorous, fast growth, high productivity and efficient nutrient uptake (Kuzovkina \u0026amp; Quigley, \u003cspan class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eThe three swale-depression cells were planted adjacent to one another with fine topsoil. Three of six wet meadow cells were planted adjacent to one another in fine topsoil, while the other three were planted in coarse topsoil and interspersed with the three riparian scrub cells. The goals of the alternating plantings were to make the site bird-friendly by providing landscape-level vegetative structure (Jason Warner, General Manager, OLSD, personal communication, June 3, 2021). Each cell consisted of 15 horizontal planting grids (12 m x 3 m), repeated down the slope. Save the Bay staff members and volunteers collected, propagated, and planted all vegetation on the ecotone slope during November and December 2015 and January 2016 (Save the Bay, 2017). In 2017, staff members then planted the basin of the adjoining treatment wetland with cattail (\u003cem\u003eTypha\u003c/em\u003e spp.) and bulrush bulbs (\u003cem\u003eSchoenoplectus\u003c/em\u003e spp.) to enhance habitat value of the wetland (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Cattail was not planted on the ecotone slope, but the species reportedly encroached onto the slope after the plantings in the treatment wetland. By 2017, the entire site was also invaded by exotic jubatagrass (\u003cem\u003eCortaderia jubata\u003c/em\u003e) (Save the Bay, 2017).\u003c/p\u003e\n\u003cp\u003eStudy Design\u003c/p\u003e\n\u003cp\u003eTo contrast successional changes since installation for the wet meadow (WM) versus riparian scrub (R) assemblages on the ecotone slope, we first compare the initial percentage of each species planted in 2015/2016 with its relative percent cover in the field in 2020/2021 using proportions compiled across all 840 wet meadow and 380 riparian scrub quadrat samples (WM\u0026thinsp;=\u0026thinsp;312 m\u003csup\u003e2\u003c/sup\u003e; R\u0026thinsp;=\u0026thinsp;141 m\u003csup\u003e2\u003c/sup\u003e) Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). We assess potential effects of fragmentation on succession and invasion in the wet meadow assemblage by contrasting changes in percent cover across the 420 quadrats from the three contiguous (\u0026ldquo;buffered\u0026rdquo; or \u0026ldquo;BWM\u0026rdquo;) wet meadow cells with the 420 quadrats from the three wet meadow cells that are interspersed with riparian scrub (\u0026ldquo;fragmented\u0026rdquo; or \u0026ldquo;FWM\u0026rdquo;). We then evaluate how the mean per-quadrat diversity of planted wet meadow species changed through time in each of the four cell types.\u003c/p\u003e\n\u003cp\u003eWe describe likely sources of encroaching plant propagules in each assemblage and cell type with a focus on occurrences of a key invasive exotic species, \u003cem\u003eCortaderia jubata\u003c/em\u003e, and dominant encroaching species.\u003c/p\u003e\n\u003cp\u003eFinally, we examine how presence of key dominant or invasive plant species, either individually or cumulatively, affects community diversity and individual percent cover of planted and volunteer species at the single quadrat level.\u003c/p\u003e\n\u003cp\u003eData Collection and Sampling\u003c/p\u003e\n\u003cp\u003eIn most cells, JF placed 10 stratified-random 0.3 m x 0.3 m PVC quadrats along each of fourteen 12-m transects distributed across eight of the horizontal planting grids for a total of 140 quadrats per cell (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). In general, JF set two transects in six of the grids, but only one transect in the remaining two. In riparian cell 12, we skipped the transects in the top two grids, as they were impenetrable with dense vegetation, yielding 120 quadrats.\u003c/p\u003e\n\u003cp\u003eJF positioned each quadrat using a vertical tape measure from the top edge of the cell and a horizontal transect tape measure from the nearest clay dividing berm. To measure percent cover accurately, JF marked each side of the quadrat with ten lines to denote 100 subdivisions. The quadrat was placed above the plants to be measured and below the horizontal transect tape. As needed, JF estimated the percent cover of \u003cem\u003eS. lasiolepis\u003c/em\u003e canopy above the quadrat using a spherical densiometer (Forestry Suppliers Concave Model-A). Due to multiple canopy layers and bare ground, total percent cover for a quadrat could exceed or be less than 100%. Field data was collected during the fall and summer, as this was the best phenological period for plant identification, and plants were identified using planting lists, iNaturalist, and the Jepson Manual (Baldwin et al., \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e). To generate 2015/16 data values, quadrats were virtually sampled from the original planting plans using Python (version 3).\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eData Analysis\u003c/h2\u003e\n \u003cp\u003eTo assess overall successional change, we first averaged the percent cover of each species over all quadrats when planted and in 2020/2021 for each of the cell types overall; WM, R, BWM, and FWM with a Texas Instrument-83 (TI-83) calculator. We also used a TI-83 calculator to calculate one-proportion \u003cem\u003ez\u003c/em\u003e-tests to estimate the likelihood that the proportions of each species in a cell-type differed statistically between the two dates.\u003c/p\u003e\n \u003cp\u003eWe also calculated Simpson\u0026rsquo;s Reciprocal Diversity Index (\u003cem\u003eRDI\u003c/em\u003e) in Microsoft Excel (version 16), using species richness and percent cover of each plant species (Tomascik \u0026amp; Sander, \u003cspan class=\"CitationRef\"\u003e1985\u003c/span\u003e; Onaindia et al., \u003cspan class=\"CitationRef\"\u003e2004\u003c/span\u003e; Oswalt et al., \u003cspan class=\"CitationRef\"\u003e2007\u003c/span\u003e), for the subset of quadrats in which any planted species survived to the 2020/2021 season, as the metric generates a null outcome for zero values.\u003c/p\u003e\n \u003cp\u003eTo assess changes in all planted species\u0026rsquo; \u003cem\u003eRDI\u003c/em\u003e since installation, we used paired \u003cem\u003et\u003c/em\u003e-tests (SPSS version 27)\u003c/p\u003e\n \u003cp\u003eBecause the data could not be normalized, we used a Mann-Whitney \u003cem\u003eU\u003c/em\u003e test in SPSS to compare the change in the \u003cem\u003eRDI\u0026rsquo;\u003c/em\u003es in the buffered and fragmented WM among three different plant community subsets: a) planted wet meadow species; b) any ecotone-slope-planted species (wet meadow, riparian scrub, or swale depression); and c) all plants found on the horizontal levee, including volunteer and exotic species.\u003c/p\u003e\n \u003cp\u003eTo assess the relative sources of propagules, encroaching or invading species were put into three categories: (a) species planted elsewhere on the ecotone slope, (b) species planted in the treatment wetland, and (c) volunteer species not planted in either the treatment wetland or the ecotone slope. We used two-proportion \u003cem\u003ez\u003c/em\u003e-tests to contrast propagules sources in WM versus R and BWM versus FWM cells. For FWM, we used the more conservative one-sided test to reflect the greater likelihood of encroachment by riparian species.\u003c/p\u003e\n \u003cp\u003eFor the principal invasive exotic species we encountered, \u003cem\u003eC. jubata\u003c/em\u003e, we used chi-square tests of independence in SPSS to compare presence/absence across quadrats in WM versus R and FWM versus BWM cells.\u003c/p\u003e\n \u003cp\u003eTo assess how the presence of \u003cem\u003eS. lasiolepis\u003c/em\u003e, \u003cem\u003eTypha\u003c/em\u003e, or both together affected planted species succession in the wet meadow assemblage, we compared RDI and total percent cover of wet meadow species in each quadrat between installation and the 2020/2021 field season using a Kruskal-Wallis test in SPSS. Since \u003cem\u003eS. lasiolepis\u003c/em\u003e was already present in the riparian area, we did not assess its effect on the riparian assemblage.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eIn 2020/2021, the dominant species on the ecotone slope were \u003cem\u003eS. lasiolepis\u003c/em\u003e and \u003cem\u003eTypha\u003c/em\u003e spp. These species both deposited thick layers of thatch. A majority of the \u003cem\u003eTypha\u003c/em\u003e that was recorded was solely thatch material. Leaf litter from \u003cem\u003eS. lasiolepis\u003c/em\u003e was found in most instances where live \u003cem\u003eS. lasiolepis\u003c/em\u003e was recorded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChanges in Plant Community Parameters: Proportional Change in Species\u0026rsquo; Cover Since Planting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the wet meadow, all species initially planted in 2015/2016 were still present in 2020/2021 (Table 2a). Proportions of \u003cem\u003eJuncus balticus articus\u003c/em\u003e, \u003cem\u003eBaccharis glutinosa\u003c/em\u003e, and \u003cem\u003eEuthamia occidentalis\u003c/em\u003e increased compared to initial plantings (\u003cem\u003ez\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.54, 5.07, 5.54, respectively, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). All other wet meadow species decreased measurably through time (\u003cem\u003ez\u003c/em\u003e \u0026lt;- 2.85, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), except for \u003cem\u003eCarex praegracilis\u003c/em\u003e, whose apparent decline was minor enough that it was not statistically detectable (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.21). In the riparian scrub cells, proportions of \u003cem\u003eSalix lasiolepis\u003c/em\u003e and \u003cem\u003eCarex barbarae\u003c/em\u003e increased substantially by 2020/2021 (\u003cem\u003ez\u003c/em\u003e\u0026thinsp;=\u0026thinsp;57.11, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; \u003cem\u003ez\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.72, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006; Table 2b), and \u003cem\u003eRubus ursinus\u003c/em\u003e maintained its original planting proportions. All other species planted in the riparian scrub cells decreased through time (\u003cem\u003ez\u003c/em\u003e \u0026lt; -2.19, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), including \u003cem\u003eCornus sericea\u003c/em\u003e and \u003cem\u003eSambucus nigra\u003c/em\u003e, which were no longer present by 2020/2021 on the ecotone slope.\u003c/p\u003e\n\u003cp\u003eEvery species planted in a wet meadow was found in greater proportion in the buffered (Table 2c) compared to the fragmented cells (Table 2d). Three wet meadow species, \u003cem\u003eAmbrosia psilostachya\u003c/em\u003e, \u003cem\u003eSymphyotricum chilense\u003c/em\u003e, and \u003cem\u003eLythrum californicum\u003c/em\u003e did not persist in any fragmented wet meadow samples.\u003c/p\u003e\n\u003ch2\u003eChanges in Plant Community Parameters: Changes in Species Diversity\u003c/h2\u003e\n\u003cp\u003eSimpson\u0026rsquo;s reciprocal diversity of planted species decreased substantially, especially in the riparian scrub assemblage, between the original installation and the 2020/2021 field season. For the wet meadow, the mean \u003cem\u003eRDI\u0026nbsp;\u003c/em\u003edropped from 0.31 when planted to 0.19 (\u003cem\u003et\u003c/em\u003e (650) = -9.14, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 5a), and the riparian scrub planted species \u003cem\u003eRDI\u003c/em\u003e dropped from 0.26 to just 0.11 in 2020/2021 (\u003cem\u003et\u003c/em\u003e (378) = -10.08, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 5b).\u003c/p\u003e\n\u003cp\u003eFor the buffered wet meadow cells, the planted \u003cem\u003eRDI\u003c/em\u003e dropped from an initial mean of 0.30 to 0.21 (t (395) = -5.07, p \u0026lt; 0.001; Figure 5c), and the fragmented wet meadow fell even further, from a mean \u003cem\u003eRDI\u0026nbsp;\u003c/em\u003eof 0.32 to 0.14 (t (254) = -8.3, p \u0026lt; 0.001; Figure 5d).\u003c/p\u003e\n\u003ch2\u003eInteractions among species in Buffered and Fragmented Wet Meadow Cells\u003c/h2\u003e\n\u003cp\u003eOverall, the buffered WM cells supported higher median diversity of native species installed on the ecotone slope than the fragmented wet meadow cells, both in terms of the WM species diversity (\u003cem\u003ez\u003c/em\u003e (standardized \u003cem\u003eU\u003c/em\u003e) = 5.31, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001\u003cem\u003e;\u0026nbsp;\u003c/em\u003eFigure 6a) and overall diversity (WM, R, and swale-depression species) (\u003cem\u003ez\u003c/em\u003e (standardized \u003cem\u003eU\u003c/em\u003e) = 2.16 \u003cem\u003ep\u003c/em\u003e = 0.031; Figure\u003cem\u003e\u0026nbsp;\u003c/em\u003e6b). When volunteer and invasive species were included, however, the fragmented WM was more diverse than the buffered WM (\u003cem\u003ez\u003c/em\u003e (standardized \u003cem\u003eU\u003c/em\u003e) = -4.6, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 6c).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSources of Encroaching and Invasive Species\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBy 2020/2021, the FWM cells had much greater percent cover of species not planted in those cells than the BWM cells (\u003cem\u003ez\u003c/em\u003e \u0026lt; -20.74, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 7a), predominately \u003cem\u003eS. lasiolepis\u003c/em\u003e from riparian scrub cells and \u003cem\u003eTypha\u003c/em\u003e from the treatment wetland. The fragmented cells also retained much lower percent cover of original wet meadow species than the buffered cells (\u003cem\u003ez\u003c/em\u003e = 32.56, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001)\u003cem\u003e.\u0026nbsp;\u003c/em\u003eAlthough fragmented and buffered WM cells did not differ in overall proportions of volunteer or exotic species (\u003cem\u003ez\u003c/em\u003e = -0.58, \u003cem\u003ep\u003c/em\u003e = 0.95), the FWM also had more quadrats with \u003cem\u003eC. jubata\u003c/em\u003e than the BWM (𝜒\u003csup\u003e2\u003c/sup\u003e(1) = 21.53, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 8).\u003c/p\u003e\u003cp\u003eThe wet meadow assemblages had a higher proportion of encroaching and invasive species than the riparian scrub assemblage (\u003cem\u003ez\u003c/em\u003e \u0026gt; 5.69, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; Figure 7b). About 39.8% of the wet meadow area contained species from other cells, mostly comprising \u003cem\u003eS. lasiolepis\u003c/em\u003e encroaching from riparian scrub cells. The riparian scrub quadrats had no detectable encroachment from wet meadow species, however \u003cem\u003eC. jubata\u003c/em\u003e occurred more frequently in the riparian scrub assemblage compared to the wet meadow (𝜒\u003csup\u003e2\u003c/sup\u003e(1) = 4.51, \u003cem\u003ep\u003c/em\u003e = 0.034; Figure 8).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eEffects of Salix lasiolepis\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e, \u003cem\u003eTypha\u003c/em\u003e on WM Diversity and Total Cover\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the wet meadow assemblage, by 2020/2021, quadrats encroached with either \u003cem\u003eS. lasiolepis\u003c/em\u003e, \u003cem\u003eTypha spp.\u003c/em\u003e, or both had lower diversity (H(3) = 45.68, p\u0026lt;0.0001; Figure 9a)\u003cem\u003e\u0026nbsp;\u003c/em\u003eand lower total percent cover of the originally planted WM species (H(3) = 316.43, p\u0026lt;0.0001; Figure 9b). The effect of S.\u003cem\u003e\u0026nbsp;lasiolepis\u0026nbsp;\u003c/em\u003epresence on total WM planted-species cover was significantly greater than Typha alone. \u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study documents a substantial reduction in plant diversity in the five years post-installation of an ecotone slope on a horizontal levee designed to protect a wastewater treatment facility on the San Francisco Bay. Both wet meadow and riparian scrub assemblages planted on the ecotone slope lost diversity over time, but the riparian scrub assemblage in particular became dominated by the hardy native \u003cem\u003eSalix lasiolepis\u003c/em\u003e. The wet meadow plant assemblage was encroached by both \u003cem\u003eS. lasiolepis\u003c/em\u003e, from interspersed riparian scrub assemblage, and \u003cem\u003eTypha\u003c/em\u003e, from the treatment wetland. Our evidence suggests that fragmentation and dominance by species with invasive tendencies played central roles in native plant succession and led to greater invasion by the dominant exotic \u003cem\u003eCortaderia jubata\u003c/em\u003e, although the different soil types across these assemblages may have played a role in their succession. Our results support the idea that designs for nature-based solutions would benefit from incorporating larger habitat patch sizes, but that they may also require ongoing intervention and adaptation to limit effects of fragmentation, species invasion, and succession and achieve habitat creation goals.\u003c/p\u003e\u003cp\u003eNatural wetland ecosystems rely on flooding and drought to maintain their biodiversity and ecological function (Middleton, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Zedler, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). This ecotone slope contrasted two native wetland plant assemblages, wet meadow and riparian scrub, which are adapted to distinct natural hydrological disturbance regimes. Shallow water tables and soil saturation are characteristic of wet meadows, with soils remaining moist for much of the year (Barbour et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Zentner et al., \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Riparian ecosystems tend to have more intense hydrological regimes, with hydrological disturbance and sediment deposition being important for maintaining riparian vegetative composition (Barbour et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Tabacchi et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). Cells on the ecotone slope, in contrast, receive constant subsurface flow, but the topsoil was often dry during our survey period. Lack of a natural hydrologic disturbance regime to break dominance may have contributed to the riparian scrub assemblage\u0026rsquo;s overwhelming growth of \u003cem\u003eS. lasiolepis\u003c/em\u003e, its loss of two planted trees, \u003cem\u003eC. sericea\u003c/em\u003e and \u003cem\u003eS. nigra\u003c/em\u003e, and reduction of most riparian understory species, helping explain why the riparian scrub assemblage lost more native diversity than the wet meadow. Although the ecotone slope\u0026rsquo;s hydrological regime was somewhat more like a wet meadow, historically wet meadows in the San Francisco Bay area are also seasonally flooded (Fox et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Early successional ecosystems are susceptible to diversity loss and woody species proliferation in the absence of seasonal disturbance (Keddy \u0026amp; Rezicek, 1986, Greenberg et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Williams et al., \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e1987\u003c/span\u003e). In our study, over five years the wet meadow assemblage transitioned from a grassland to a forb and shrubland. In 2012, Ratajczack et al. documented that woody species encroachment in grasslands reduces community species richness, and several authors have shown that \u003cem\u003eBaccharis pilularis\u003c/em\u003e invasion completely changes the plant community and ecosystem function of grasslands (Williams et al., \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e1987\u003c/span\u003e; Zavaleta \u0026amp; Kettley, \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMany authors have argued that communities composed of species that vary in phenology, reproductive process, and ecological function resist invasion, particularly by functionally similar species (Byun, 2013; Fag\u0026uacute;ndez \u0026amp; Lema, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Fried et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Zedler, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). The riparian scrub community may have experienced substantially less \u003cem\u003eTypha\u003c/em\u003e encroachment compared to the wet meadow due to inclusion of \u003cem\u003eS. lasiolepis\u003c/em\u003e in the planting palette. Plumb et al., (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) document considerable reduction of \u003cem\u003eTypha\u003c/em\u003e biomass under increased shade and moisture of hardwood canopy. By that argument, light conditions in the wet meadow may have been more conducive to \u003cem\u003eTypha\u003c/em\u003e establishment, persistence and survival than in the riparian scrub assemblage. Over twice as much \u003cem\u003eTypha\u003c/em\u003e invaded the fragmented WM, however, despite it having much higher levels of \u003cem\u003eS. lasiolepis\u003c/em\u003e than the buffered WM. Compared to larger habitat patches, fragments provide a disproportionate amount of edge, which is conducive to the introduction and establishment of species with invasive qualities (Cronk \u0026amp; Fuller, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). In this case, encroachment of \u003cem\u003eS. lasiolepis\u003c/em\u003e, a riparian scrub assemblage species, into the fragmented wet meadow can be explained by the large amount of shared edge facilitating its movement. Greater \u003cem\u003eTypha\u003c/em\u003e and \u003cem\u003eC. jubata\u003c/em\u003e encroachment into fragmented versus buffered wet meadow is more puzzling, however, and suggests that encroaching \u003cem\u003eS. lasiolepis\u003c/em\u003e may even have facilitated invasions of other species at lower densities, possibly by shading out smaller WM and other riparian species.\u003c/p\u003e\u003cp\u003eCreated urban wetlands that treat wastewater may be particularly vulnerable to domination by vegetative monotypes, due to the continuous input of nutrient-rich wastewater (Canavan et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Green \u0026amp; Galatowitsch, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). Consistent with Zedler and Kercher\u0026rsquo;s (\u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2004\u003c/span\u003e) efficient use hypothesis, \u003cem\u003eSalix lasiolepis\u0026rsquo;\u003c/em\u003e superior growth and productivity, more efficient nutrient uptake than competitors, and drought and salinity tolerance likely permitted it to withstand the conditions on the ecotone slope better and even directly suppress other planted species (Ericsson, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Elowson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Frieswyk \u0026amp; Zedler, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Kuzovkina \u0026amp; Quigley, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Woo \u0026amp; Zedler, \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). Unlike other species, \u003cem\u003eS. lasiolepis\u003c/em\u003e often benefits from partial limb breaks as a means for lateral dispersal through epicormic shoots and adventitious roots. Using growth morphology as a dispersal mechanism allows it to outcompete neighboring plants (Boland \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). \u003cem\u003eTypha\u003c/em\u003e is wind pollinated and some species of \u003cem\u003eTypha\u003c/em\u003e can have up to 420\u0026nbsp;million pollen grains per inflorescence, which can remain viable for weeks (Grace \u0026amp; Harrison \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1986\u003c/span\u003e). Once established, \u003cem\u003eTypha\u003c/em\u003e spp. form dense, nearly monotypic stands; it is often taller than the species it displaces; it uses nutrients efficiently; and it leaves behind an abundant amount of thatch that can suppress other species\u0026rsquo; germination or growth (Larkin et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Newman et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Vaccaro et al., \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWe find that abundance of the two dominant native wetland plants in our system, \u003cem\u003eSalix lasiolepis\u003c/em\u003e and \u003cem\u003eTypha\u003c/em\u003e spp. reduced plant community diversity and altered community structure where they invaded the wet meadow. Weiher \u0026amp; Keddy (\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e1995\u003c/span\u003e) suggest that \u003cem\u003eTypha\u003c/em\u003e litter can even act as a \u0026ldquo;filter,\u0026rdquo; causing extant plant communities to differ from the communities represented in the seed bank.\u003c/p\u003e\u003cp\u003eThe combined presence of \u003cem\u003eTypha\u003c/em\u003e and \u003cem\u003eSalix lasiolepis\u003c/em\u003e and layers of thatch in the fragmented wet meadow cells may have created a double encroachment pressure, resulting in the greater declines in diversity than in the buffered, which only faced encroachment from treatment wetland plants. Overall, although Typha proved to be an important expansive species, the native, planted, riparian species S. lasiolepis proved to have the greatest effect on ecosystem succession and diversity in the absence of natural hydrologic disturbance.\u003c/p\u003e\u003cp\u003eThe major non-native invasive threat to the wet meadow was \u003cem\u003eCordateria jubata\u003c/em\u003e. \u003cem\u003eC. jubata\u003c/em\u003e has spread throughout the ecotone slope, although it has been actively managed by the OLSD (Personal communication, Jason Warner, General Manager, OLSD and David Sedlak, Environmental Engineering, U.C. Berkeley). \u003cem\u003eC. jubata\u003c/em\u003e demonstrates rapid growth and resource use under high water and nitrogen availability conditions (Vourlitis \u0026amp; Kroon, \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). It also produces copious seeds, allowing its populations to persist by creating strong and continuous propagule pressure that considerably increases the probability of further expansion (Lambrinos, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The greater presence of \u003cem\u003eC. jubata\u003c/em\u003e, in the riparian scrub and fragmented wet meadow cells may have resulted from the effects of fragmentation, including the loss of three planted species in the fragmented wet meadow, which could have left more niche availability for \u003cem\u003eC. jubata\u003c/em\u003e to fill and colonize.\u003c/p\u003e\u003cp\u003eIn addition to abiotic disturbances, wetland ecosystems in California evolved for millennia with management, such as burning, harvesting, and tending, by indigenous peoples. Natural anthropogenic disturbance shaped the distribution and abundance of managed species (Hankins, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Lightfoot \u0026amp; Lopez, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Stevens, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and the role indigenous management has played for millennia in maintaining biodiversity is well-documented (Berkes et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Mistry \u0026amp; Bernardi, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Stevens, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Zedler \u0026amp; Stevens, \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Stevens (\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) found that indigenous gathering, tending, and cultivating of \u003cem\u003eC. barbarae\u003c/em\u003e for basket weaving enhanced its distribution and abundance, and understory species, such as \u003cem\u003eC. barbarae\u003c/em\u003e, often fail to colonize restored riparian forests without human support.\u003c/p\u003e\u003cp\u003e\u003cem\u003eTypha\u003c/em\u003e and \u003cem\u003eSalix\u003c/em\u003e have also been harvested and used by native peoples worldwide for food, medicine, clothing, shelter, and other tools (Bates \u0026amp; Lee, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e1990\u003c/span\u003e; Grace \u0026amp; Harrison, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1986\u003c/span\u003e; Liptay, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1988\u003c/span\u003e; Motivans \u0026amp; Apfelbaum, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1987\u003c/span\u003e; Prashith et al., 2017; Tawfeek et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Through genocide, slavery, and disease, however, regular indigenous ecosystem management and tending in California abruptly declined with European colonization (Zedler \u0026amp; Stevens, \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Loss of harvesting and burning led riparian canopies to close and tule marshes to progress to impenetrable and senescent states. Interestingly, although \u003cem\u003eC. barbarae\u003c/em\u003e in this system successionally declined in both fragmented and buffered wet meadow cells, the species expanded without intervention in the riparian scrub assemblage, reflecting its tolerance and higher survivability under low-light conditions from a \u003cem\u003eS. lasiolepis\u003c/em\u003e canopy (Moore et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). This suggests that more understanding of interspecific interactions and effects of traditional management as a natural disturbance are needed to maintain habitat diversity and quality.\u003c/p\u003e"},{"header":"Conclusions and Recommendations","content":"\u003cp\u003eOur findings underscore the importance of nuanced application of nature-based solutions. In the absence of natural disturbance processes, such as seasonal overland water flow or scouring, fragmentation may drive constructed wetlands to progress to a successional state dominated by fewer species. In this horizontal levee system, plant assemblage and patch size both strongly influenced community invasibility, expansion of dominant natives, \u003cem\u003eTypha\u003c/em\u003e and \u003cem\u003eS. lasiolepis\u003c/em\u003e, and spread of non-native \u003cem\u003eC. jubata\u003c/em\u003e. Future projects would benefit from planting larger patches with lower edge ratios to facilitate ecosystem resistance to invasion and diversity loss.\u003c/p\u003e\u003cp\u003eThe biological complexity of historic undamaged ecosystems usually informs restoration of natural disturbance regimes (Angelstam, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Middleton, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Odion \u0026amp; Sarr, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) or active management (Hobbs et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) to achieve a specific desired ecosystem or state. Constructed treatment wetlands designed to fulfill multiple goals (wastewater treatment, flood control, and native habitat creation) tend to be limited in the amount of hydrologic disturbance they can incorporate.\u003c/p\u003e\u003cp\u003eSubsurface flow is important for removing contaminants, some projects\u0026rsquo; primary goal, but overland flow, or at least thorough soil saturation, is important for maintaining wetland habitats on the ecotone slope. Previous authors find that natural hydrological processes are overlooked in constructed wetlands (Grimm \u0026amp; K\u0026ouml;ppel, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), and temporal and spatial regimes are mostly homogenized (Bockelmann et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). The final 2018 phase of this project removed most of the overland flow, eliminating the natural hydrological disturbance.\u003c/p\u003e\u003cp\u003eIn cases such as this, designing plant assemblages to resist invasion, possibly by installing later successional habitats with fewer, more competitive species, may reduce costs of collecting, propagating, and growing plant species while still meeting habitat goals, and retaining overland flow and incorporating anthropogenic disturbances like mowing may be practical to maintain species diversity (Zedler, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2000\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eGiven the current loss of biodiversity and wetland habitat worldwide and in California, projects like this one are crucial to restore healthy, diverse urban ecosystems and make cities more livable and resilient for people, plants, and animals, especially in this era of global climate change (Matthies et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Norton et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Sea-level rise will only increase constraints on wetland habitat. We have shown that plant communities in projects such as this must be monitored and maintained to ensure they maintain the biodiversity needed to sustain critical habitat and ecological resilience, vibrant green spaces, and resilient urban ecosystems.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThis research took place on the ancestral and unceded land of the Muwekma Ohlone. This land continues to be of great importance to the Muwekma Ohlone tribe. Indigenous stewardships practices have helped inform the lens through which we view our work and such knowledge was crucial to the management suggestions put forward in this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe thank Dr. Metha Klock and Dr. Anand of San Jose State University for their feedback through the initial development of this paper. We thank the Oro Loma Sanitary District and former general manager Jason Warner for their support and cooperation during the field portion of this study. We thank Jessie Olson and Donna Ball from Save the Bay for providing the initial background information necessary to perform this work. We also extend thanks to Angela Perantoni and Aidan Cecchetti from the Sedlak Lab at UC Berkeley for information regarding their experiments on the Oro Loma Horizontal Levee. We extend additional thanks to Anita Wah for statistical advice and Marquess Valdez for assistance with specific analyses.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eCompeting Interests\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions\u003c/p\u003e\n\u003cp\u003eJoia Fishman and Dr. Rachel O\u0026rsquo;Malley conceived the ideas and designed methodology; JF collected the data; JF and RM analyzed the data; JF wrote the first draft of the manuscript. Both authors contributed critically to the drafts and gave final approval for publication.\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eData availability\u003c/p\u003e\n\u003cp\u003eUpon publication, all data associated with this manuscript will be made publicly available in the Dryad digital repository.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAngelstam PK (1998) Maintaining and restoring biodiversity in European boreal forests by developing natural disturbance regimes. J Veg Sci 9(4):593\u0026ndash;602. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/3237275\u003c/span\u003e\u003cspan address=\"10.2307/3237275\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAydin Temel F, Avci E, Ardali Y (2018) Full scale horizontal subsurface flow constructed wetlands to treat domestic wastewater by \u003cem\u003eJuncus acutus\u003c/em\u003e and \u003cem\u003eCortaderia selloana\u003c/em\u003e. Int J Phytoremediation 20(3):264\u0026ndash;273. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/15226514.2017.1374336\u003c/span\u003e\u003cspan address=\"10.1080/15226514.2017.1374336\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBalcombe CK, Anderson JT, Fortney RH, Rentch JS, Grafton WN, Kordek WS (2005) A comparison of plant communities in mitigation and reference wetlands in the mid-appalchians. Wetlands 25(1):130\u0026ndash;142. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libaccess.sjlibrary\u003c/span\u003e\u003cspan address=\"https://doi-org.libaccess.sjlibrary\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e.org/10.1672/0277-5212(2005)025[0130:ACOPCI]2.0.CO;2\u003c/span\u003e\u003cspan address=\".10.1672/0277-5212(2005)025[0130:ACOPCI]2.0.CO;2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaldwin BG, Goldman DH, Keil DJ, Patterson R, Rosatti TJ, Wilken DH (eds) (2012) The Jepson manual: Vascular plants of California. University of California Press\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarbour M, Keeler-Wolf T, Schoenherr AA (eds) (2007) Terrestrial vegetation of California. University of California Press\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBates CD, Lee MJ (1990) Tradition and innovation: A basket history of the Indians of the Yosemite-Mono Lake area. Yosemite Association\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBerkes F, Colding J, Folke C (2000) Rediscovery of traditional ecological knowledge as adaptive management. Ecol Appl 10(5):1251\u0026ndash;1262. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1890/1051-0761(2000)010\u003c/span\u003e\u003cspan address=\"10.1890/1051-0761(2000)010\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e[1251:ROTEKA]2.0.CO;2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBockelmann AC, Bakker JP, Neuhaus R, Lage J (2002) The relation between vegetation zonation, elevation and inundation frequency in a Wadden Sea salt marsh. Aquat Bot 73(3):211\u0026ndash;221. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0304-3770(02)00022-0\u003c/span\u003e\u003cspan address=\"10.1016/S0304-3770(02)00022-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBoland J (2024) The role of partial limb breaks in the growth and persistence of arroyo willow (\u003cem\u003eSalix lasiolepis\u003c/em\u003e). Madro\u0026ntilde;o 71(2):71\u0026ndash;83. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3120/0024-9637-71.2.71\u003c/span\u003e\u003cspan address=\"10.3120/0024-9637-71.2.71\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eByun C, de Blois S, Brisson J (2013) Plant functional group identity and diversity determine biotic resistance to invasion by an exotic grass. J Ecol 101(1):128\u0026ndash;139. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2745.13419\u003c/span\u003e\u003cspan address=\"10.1111/1365-2745.13419\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCanavan K, Paterson ID, Lambertini C, Hill MP (2018) Expansive reed populations\u0026mdash;alien invasion or disturbed wetlands? AoB Plants 10(2):ply014. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/aobpla/ply014\u003c/span\u003e\u003cspan address=\"10.1093/aobpla/ply014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCecchetti AR, Stiegler AN, Graham KE, Sedlak DL (2020) The horizontal levee: A multi-benefit nature-based treatment system that improves water quality and protects coastal levees from the effects of seal level rise. Water Res X 7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.wroa.2020.100052\u003c/span\u003e\u003cspan address=\"10.1016/j.wroa.2020.100052\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCostanza R, P\u0026eacute;rez-Maqueo O, Luisa Martinez M, Sutton P, Anderson SJ, Mulder K (2008) The value of coastal wetlands for hurricane protection. Ambio, \u003cem\u003e37\u003c/em\u003e(4). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.jstor.org/stable/25547893\u003c/span\u003e\u003cspan address=\"https://www.jstor.org/stable/25547893\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCronk QC, Fuller JL (1995) Plant invaders: The threat to natural ecosystems. Chapman and Hall\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDe Martis G, Mulas B, Malavasi V, Marignani M (2016) Can artificial ecosystems enhance local biodiversity? The case of a constructed wetland in a Mediterranean urban context. Environ Manage 57(5):1088\u0026ndash;1097. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00267-016-0668-4\u003c/span\u003e\u003cspan address=\"10.1007/s00267-016-0668-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDuarte CM, Losada IJ, Hendriks IE, Mazarrasa I, Marb\u0026agrave; N (2013) The role of coastal plant communities for climate change mitigation and adaptation. Nature 3(11):961\u0026ndash;968. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/nclimate1970\u003c/span\u003e\u003cspan address=\"10.1038/nclimate1970\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eElowson S (1999) Willow as a vegetation filter for cleaning of polluted drainage water from agricultural land. Biomass Bioenergy 16:281\u0026ndash;290. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0961-9534(98)00087-7\u003c/span\u003e\u003cspan address=\"10.1016/S0961-9534(98)00087-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEricsson T (1981) Growth and nutrition in three \u003cem\u003eSalix\u003c/em\u003e clones grown in low conductivity solutions. Physiol Plant 52:239\u0026ndash;244. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1399-3054.1981.tb08499.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1399-3054.1981.tb08499.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFag\u0026uacute;ndez J, Lema M (2019) A competition experiment of an invasive alien grass and two native species: Are functionally similar species better competitors? Biol Invasions 21(12):3619\u0026ndash;3631. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10530-019-02073-y\u003c/span\u003e\u003cspan address=\"10.1007/s10530-019-02073-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFluet-Chouinard E, Stocker BD, Zhang Z et al (2023) Extensive global wetland loss over the past three centuries. Nature 614:281\u0026ndash;286. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41586-022-05572-6\u003c/span\u003e\u003cspan address=\"10.1038/s41586-022-05572-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFox P, Hutton PH, Howes DJ, Draper AJ, Sears L (2015) Reconstructing the natural hydrology of the San Francisco Bay\u0026ndash;Delta watershed. Hydrol Earth Syst Sci 19(10):4257\u0026ndash;4274. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5194/hess-19-4257-2015\u003c/span\u003e\u003cspan address=\"10.5194/hess-19-4257-2015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFried G, Belaud A, Chauvel B (2015) Ecology and impact of an emerging invasive species in France: Western ragweed (\u003cem\u003eAmbrosia psilostachya\u003c/em\u003e DC). Revue d\u0026rsquo;Ecologie (Terre et Vie) 70:53\u0026ndash;67. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://hdl.handle.net/2042/57884\u003c/span\u003e\u003cspan address=\"http://hdl.handle.net/2042/57884\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFrieswyk CB, Zedler JB (2006) Do seed banks confer resilience to coastal wetlands invaded by \u003cem\u003eTypha\u003c/em\u003e x glauca? Botany 84(12):1883\u0026ndash;1892. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1139/B06-100\u003c/span\u003e\u003cspan address=\"10.1139/B06-100\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrace JB, Harrison JS (1986) The biology of Canadian weeds.: 73. Typha latifolia L., Typha angustifolia L. and Typha x glauca Godr. Can J Plant Sci 66(2):361\u0026ndash;379. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4141/cjps86-051\u003c/span\u003e\u003cspan address=\"10.4141/cjps86-051\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrebenshchykova Z, Fr\u0026eacute;dette C, Chazarenc F, Comeau Y, Brisson J (2019) Establishment and potential use of woody species in treatment wetlands. Int J Phytoremediation 22(3):295\u0026ndash;304. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/15226514.2019.1658712\u003c/span\u003e\u003cspan address=\"10.1080/15226514.2019.1658712\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGreen EK, Galatowitsch SM (2002) Effects of \u003cem\u003ePhalaris arundinacea\u003c/em\u003e and Nitrate-N addition on the establishment of wetland. J Appl Ecol 39(1):134\u0026ndash;144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/j.1365-2664.2002.00702.x\u003c/span\u003e\u003cspan address=\"10.1046/j.1365-2664.2002.00702.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGreenberg CH, Collins B, Thompson FR, McNab WH (2011) Introduction: What are early successional habitats, why are they important, and how can they be sustained? In \u003cem\u003eSustaining young forest communities\u003c/em\u003e (pp. 1\u0026ndash;10). Springer Dordrecht. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://link.springer.com/chapter/\u003c/span\u003e\u003cspan address=\"https://link.springer.com/chapter/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/978-94-007-1620-9_1\u003c/span\u003e\u003cspan address=\"10.1007/978-94-007-1620-9_1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrimm M, K\u0026ouml;ppel J (2019) Biodiversity offset program design and implementation. Sustainability 11(24):6903. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/su11246903\u003c/span\u003e\u003cspan address=\"10.3390/su11246903\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGruber H, Wiessner A, Kuschk P, Kaestner M, Appenroth KJ (2008) Physiological responses of Juncus effusus (rush) to chromium and relevance for wastewater treatment in constructed wetlands. Int J Phytoremediation 10(2):79\u0026ndash;90. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/15226510801913306\u003c/span\u003e\u003cspan address=\"10.1080/15226510801913306\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHankins DL (2013) The effects of indigenous prescribed fire on riparian vegetation in central California. Ecol Processes 2(1):1\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/2192-1709-2-24\u003c/span\u003e\u003cspan address=\"10.1186/2192-1709-2-24\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHeaven JB, Gross FE, Gannon AT (2003) Vegetation comparison of a natural and a created emergent marsh wetland. Southeast Nat 2(2):195\u0026ndash;206. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1656/1528-7092\u003c/span\u003e\u003cspan address=\"10.1656/1528-7092\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e(2003)002[0195:VCOANA]2.0.CO;2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHobbs RJ, Jentsch A, Temperton VM (2007) Restoration as a process of assembly and succession mediated by disturbance. In \u003cem\u003eLinking restoration and ecological succession\u003c/em\u003e (pp. 150\u0026ndash;167). Springer. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://link.springer.com/chapter/\u003c/span\u003e\u003cspan address=\"https://link.springer.com/chapter/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/978-0-387-35303-6_7\u003c/span\u003e\u003cspan address=\"10.1007/978-0-387-35303-6_7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoulahan JE, Findlay CS (2004) Effect of invasive plant species on temperate wetland plant diversity. Conserv Biol 18(4):1132\u0026ndash;1138. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1523-1739.2004.00391.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1523-1739.2004.00391.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHummel MA, Berry MS, Stacey MT (2018) Sea level rise impacts on wastewater treatment systems along the U.S. coasts. Earths Future 6(4):622\u0026ndash;633. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.1002/2017EF000805\u003c/span\u003e\u003cspan address=\"10.1002/2017EF000805\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKeddy PA, Reznicek AA (1986) Great Lakes vegetation dynamics: The role of fluctuating water levels and buried seeds. J Great Lakes Res 12(1):25\u0026ndash;36. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0380-1330(86)71697-3\u003c/span\u003e\u003cspan address=\"10.1016/S0380-1330(86)71697-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKuzovkina YA, Quigley MF (2005) Willow beyond wetlands: Uses of \u003cem\u003eSalix l\u003c/em\u003e. species for environmental projects. Water Air Soil Pollut 162:183\u0026ndash;204. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11270-005-6272-5\u003c/span\u003e\u003cspan address=\"10.1007/s11270-005-6272-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLambrinos JG (2008) The impact of the invasive alien grass \u003cem\u003eCortaderia jubata\u003c/em\u003e (Lemoine) Stapf on an endangered Mediterranean-type shrubland in California. Divers Distrib 6(5):217\u0026ndash;231. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/J.1472-4642.2000.00086.X\u003c/span\u003e\u003cspan address=\"10.1046/J.1472-4642.2000.00086.X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLarkin DJ, Freyman MJ, Lishawa SC, Geddes P, Tuchman NC (2012) Mechanisms of dominance by the invasive hybrid cattail \u003cem\u003eTypha\u003c/em\u003e 3 glauca. Biol Invasions 14(1):65\u0026ndash;77. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10530-011-0059-y\u003c/span\u003e\u003cspan address=\"10.1007/s10530-011-0059-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLightfoot KG, Lopez V (2013) The study of indigenous management practices in California: An introduction. Calif Archaeol 5(2):209\u0026ndash;219. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1179/1947461X13Z.00000000011\u003c/span\u003e\u003cspan address=\"10.1179/1947461X13Z.00000000011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiptay A (1988) Typha: Review of historical use and growth and nutrition. In \u003cem\u003eI International symposium on diversification of vegetable crops 242\u003c/em\u003e (pp. 231\u0026ndash;238). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.17660/ActaHortic.1989.242.31\u003c/span\u003e\u003cspan address=\"10.17660/ActaHortic.1989.242.31\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMajor DC, Omojola A, Dettinger M, Hanson RT, Sanchez-Rodriguez R (2011) Climate change, water, and wastewater in cities. In \u003cem\u003eClimate change and cities: First assessment report of the urban climate change research network\u003c/em\u003e (pp. 113\u0026ndash;144). Cambridge University Press. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://uccrn.ei.columbia.edu/sites/default/files/content/docs/ARC3.1/ARC3-Chapter-5.pdf\u003c/span\u003e\u003cspan address=\"https://uccrn.ei.columbia.edu/sites/default/files/content/docs/ARC3.1/ARC3-Chapter-5.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eManuel J (2006) In Katrina\u0026rsquo;s wake. Environ Health Perspect 114(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1289/ehp.114-a32\u003c/span\u003e\u003cspan address=\"10.1289/ehp.114-a32\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarkus-Michalczyk H, Zhu Z, Bouma TJ (2019) Morphological and biomechanical responses of floodplain willows to tidal flooding and salinity. Freshw Biol 64(5):913\u0026ndash;925. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/fwb.13273\u003c/span\u003e\u003cspan address=\"10.1111/fwb.13273\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMatthies SA, Rueter S, Schaarschmidt F, Prasse R (2017) Determinants of species richness within and across taxonomic groups in urban green spaces. Urban Ecosyst 20(4):897\u0026ndash;909. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11252-017-0642-9\u003c/span\u003e\u003cspan address=\"10.1007/s11252-017-0642-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMiddleton BA (1999) Wetland restoration, flood pulsing, and disturbance dynamics. John Wiley \u0026amp; Sons, Inc.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMistry J, Bernardi A (2016) Bridging indigenous and scientific knowledge. Science 352(6291):1274\u0026ndash;1275. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/doi:10.1126/science.aaf1160\u003c/span\u003e\u003cspan address=\"doi:10.1126/science.aaf1160\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoore PL, Holl KD, Wood DM (2011) Strategies for restoring native riparian understory plants along the Sacramento River: Timing, shade, non-native control, and planting method. San Francisco Estuary Watershed Sci 9(2). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.15447/sfews.2014v9iss2art1\u003c/span\u003e\u003cspan address=\"10.15447/sfews.2014v9iss2art1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMotivans K, Apfelbaum S (1987) \u003cem\u003eElement stewardship abstract for Typha spp\u003c/em\u003e. The Nature Conservancy. https://doi.org/10.16/0890037X(2000)014[0446:CCTLL] 2.0.CO;2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNewman S, Grace JB, Koebel JW (1996) Effects of nutrients and hydroperiod on \u003cem\u003eTypha\u003c/em\u003e, \u003cem\u003eCladium\u003c/em\u003e, and \u003cem\u003eEleocharis\u003c/em\u003e: Implications for everglades restoration. Ecol Appl 6(3):774\u0026ndash;783. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/2269482\u003c/span\u003e\u003cspan address=\"10.2307/2269482\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNorton BA, Evans KL, Warren PH (2016) Urban biodiversity and landscape ecology: Patterns, processes and planning. Curr Landsc Ecol Rep 1(4):178\u0026ndash;192. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s40823-016-0018-5\u003c/span\u003e\u003cspan address=\"10.1007/s40823-016-0018-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOdion DC, Sarr DA (2007) Managing disturbance regimes to maintain biological diversity in forested ecosystems of the Pacific Northwest. For Ecol Manag 246(1):57\u0026ndash;65. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.foreco.2007.03.050\u003c/span\u003e\u003cspan address=\"10.1016/j.foreco.2007.03.050\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOnaindia M, Dominguez I, Albizu I, Garbisu C, Amezaga I (2004) Vegetation diversity and vertical structure as indicators of forest disturbance. For Ecol Manag 195(3):341\u0026ndash;354. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.foreco.2004.02.059\u003c/span\u003e\u003cspan address=\"10.1016/j.foreco.2004.02.059\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOswalt CM, Oswalt SN, Clatterbuck WK (2007) Effects of \u003cem\u003eMicrostegium vimineum\u003c/em\u003e (Trin.) A. Camus on native woody species density and diversity in a productive mixed-hardwood forest in Tennessee. \u003cem\u003eForest Ecology and Management\u003c/em\u003e, \u003cem\u003e242\u003c/em\u003e(2\u0026ndash;3), 727\u0026ndash;732. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.foreco.2007.02.008\u003c/span\u003e\u003cspan address=\"10.1016/j.foreco.2007.02.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePlumb P, Day SD, Wynn-Thompson TM, Seiler JR (2013) Relationship between woody plant colonization and \u003cem\u003eTypha\u003c/em\u003e L. Encroachment in stormwater detention basins. Environ Manage 52:861\u0026ndash;876. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00267-013-0137-2\u003c/span\u003e\u003cspan address=\"10.1007/s00267-013-0137-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePrashith Kekuda T, Vinayaka K, Raghavendra H (2017) Ethnobotanical uses, phytochemistry and biological activities of \u003cem\u003eSalix tetrasperma\u003c/em\u003e roxb. (Salicaceae)-A review. \u003cem\u003eJournal of Medicinal Plants Studies\u003c/em\u003e, \u003cem\u003e5\u003c/em\u003e(5), 201\u0026ndash;206. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.plantsjournal.com/archives/?\u003c/span\u003e\u003cspan address=\"https://www.plantsjournal.com/archives/?\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e year\u0026thinsp;=\u0026thinsp;2017\u0026amp;vol\u0026thinsp;=\u0026thinsp;5\u0026amp;issue\u0026thinsp;=\u0026thinsp;5\u0026part;\u0026thinsp;=\u0026thinsp;C\u0026amp;ArticleId\u0026thinsp;=\u0026thinsp;703\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRatajczak Z, Nippert JB, Collins SL (2012) Woody encroachment decreases diversity across North American grasslands and savannas. Ecology 93(4):697\u0026ndash;703. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1890/11-1199.1\u003c/span\u003e\u003cspan address=\"10.1890/11-1199.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSagga\u0026iuml; MM, Ainouche A, Nelson M, Cattin F, Amrani E, A (2017) Long-term investigation of constructed wetland wastewater treatment and reuse: Selection of adapted plant species for metaremediation. J Environ Manage 201:120\u0026ndash;128. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jenvman.2017.06.040\u003c/span\u003e\u003cspan address=\"10.1016/j.jenvman.2017.06.040\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStevens ML (2020) Eco-cultural restoration of riparian wetlands in California: Case study of white root (Carex barbarae Dewey; Cyperaceae). Wetlands 40(6):2461\u0026ndash;2475. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s13157-020-01323-3\u003c/span\u003e\u003cspan address=\"10.1007/s13157-020-01323-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStohlgren TJ, Bull KA, Otsuki Y, Villa CA, Lee M (1998) Riparian zones as havens for exotic plant species in the central grasslands. Plant Ecol 138(1):113\u0026ndash;125. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1023/A:1009764909413\u003c/span\u003e\u003cspan address=\"10.1023/A:1009764909413\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTabacchi E, Correll DL, Hauer R, Pinay G, Planty-Tabacchi AM, Wissmar RC (1998) Development, maintenance, and role of riparian vegetation in the river landscape. Freshw Biol 40(3):497\u0026ndash;516. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libaccess.sjlibrary\u003c/span\u003e\u003cspan address=\"https://doi-org.libaccess.sjlibrary\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e.org/10.1046/j.1365-2427.1998.00381.x\u003c/span\u003e\u003cspan address=\".10.1046/j.1365-2427.1998.00381.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTawfeek N, Mahmoud MF, Hamdan DI, Sobeh M, Farrag N, Wink M, El-Shazly AM (2021) Phytochemistry, pharmacology and medicinal uses of plants of the genus Salix: An updated review. Front Pharmacol 50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fphar.2021.593856\u003c/span\u003e\u003cspan address=\"10.3389/fphar.2021.593856\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTaylor-Burns R, Reguero BG, Barnard PL et al (2025) Nature-based solutions extend the lifespan of a regional levee system under climate change. Sci Rep 15:16218. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-025-99762-7\u003c/span\u003e\u003cspan address=\"10.1038/s41598-025-99762-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTickner DP, Angold PG, Gurnell AM, Mountford JO (2001) Riparian plant invasions: Hydrogeomorphological control and ecological impacts. Prog Phys Geogr 25(1):22\u0026ndash;52. https://doi.org/10.1177%2F030913330102500102\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTomascik T, Sander F (1985) Effects of eutrophication on reef-building corals. Mar Biol 87(2):143\u0026ndash;155. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00539422\u003c/span\u003e\u003cspan address=\"10.1007/BF00539422\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eU.S. Census Bureau (2021) \u003cem\u003eEmergency management coastal areas\u003c/em\u003e. Census.gov. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.census.gov/topics/preparedness/about/coastal-areas.html\u003c/span\u003e\u003cspan address=\"https://www.census.gov/topics/preparedness/about/coastal-areas.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVaccaro LE, Bedford BL, Johnston CA (2009) Litter accumulation promotes dominance of invasive species of cattails (\u003cem\u003eTypha\u003c/em\u003e spp.) in Lake Ontario wetlands. Wetlands 2009 29(3):1036\u0026ndash;1048. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1672/08-28.1\u003c/span\u003e\u003cspan address=\"10.1672/08-28.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVourlitis GL, Kroon JL (2013) Growth and resource use of the invasive grass, Pampasgrass (Cortaderia selloana), in response to nitrogen and water availability. Weed Sci 61(1):117\u0026ndash;125. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1614/WS-D-11-00220.1\u003c/span\u003e\u003cspan address=\"10.1614/WS-D-11-00220.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeiher E, Keddy PA (1995) The assembly of experimental wetland plant communities. Oikos 323\u0026ndash;335. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/3545956\u003c/span\u003e\u003cspan address=\"10.2307/3545956\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWilliams K, Hobbs RJ, Hamburg SP (1987) Invasion of an annual grassland in Northern California by \u003cem\u003eBaccharis pilularis\u003c/em\u003e ssp. \u003cem\u003econsanguinea\u003c/em\u003e. \u003cem\u003eOecologia 1987\u003c/em\u003e, \u003cem\u003e72\u003c/em\u003e(3), 461\u0026ndash;465. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00377580\u003c/span\u003e\u003cspan address=\"10.1007/BF00377580\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWoo I, Zedler JB (2002) Can nutrients alone shift a sedge meadow towards dominance by the invasive \u003cem\u003eTypha\u003c/em\u003e \u0026times; \u003cem\u003eglauca\u003c/em\u003e? Wetlands 22(3):509\u0026ndash;521. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1672/0277-5212(\u003c/span\u003e\u003cspan address=\"10.1672/0277-5212(\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e2002)022[0509:CNASAS]2.0.CO;2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYoung-Mathews A, Winslow SR (2010) Plant guide for beardless wildrye (Leymus triticoides). USDA-Natural Resources Conservation Service. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/capmcpg9969.pdf\u003c/span\u003e\u003cspan address=\"https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/capmcpg9969.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Plant Materials Center\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZavaleta ES, Kettley LS (2006) Ecosystem change along a woody invasion chronosequence in a California grassland. J Arid Environ 66(2):290\u0026ndash;306. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jaridenv.2005.11.008\u003c/span\u003e\u003cspan address=\"10.1016/j.jaridenv.2005.11.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZedler JB (2000) Progress in wetland restoration ecology. Tree 15(10):402\u0026ndash;407. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0169-5347(00)01959-5\u003c/span\u003e\u003cspan address=\"10.1016/S0169-5347(00)01959-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZedler JB (2004) Compensating for wetland losses in the United States. Ibis 146:92\u0026ndash;100\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZedler JB, Kercher S (2004) Causes and consequences of invasive plants in wetlands: Opportunities, opportunists, and outcomes. CRC Crit Rev Plant Sci 23(5):431\u0026ndash;452. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/07352680490514673\u003c/span\u003e\u003cspan address=\"10.1080/07352680490514673\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZedler JB, Kercher S (2005) Wetland resources: Status, trends, ecosystem services, and restorability. Annu Rev Environ Resour 30(1):39\u0026ndash;74. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1146/annurev.energy.30.050504.144248\u003c/span\u003e\u003cspan address=\"10.1146/annurev.energy.30.050504.144248\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZedler JB, Stevens ML (2018) Western and traditional ecological knowledge in ecocultural restoration. San Francisco Estuary Watershed Sci 16(3). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.15447/sfews.2018v16iss3art2\u003c/span\u003e\u003cspan address=\"10.15447/sfews.2018v16iss3art2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZentner J, Glaspy J, Schenk D (2003) Wetland and riparian woodland restoration costs. Ecol Restor 21(3):166\u0026ndash;173. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.jstor.org/stable/43440447\u003c/span\u003e\u003cspan address=\"https://www.jstor.org/stable/43440447\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang C, Wen L, Wang Y, Liu C, Zhou Y, Lei G (2020) Can constructed wetlands be wildlife refuges? A review of their potential biodiversity conservation value. Sustainability 12(4):1442. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/su12041442\u003c/span\u003e\u003cspan address=\"10.3390/su12041442\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 and 2 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"horizontal levee, green infrastructure, wastewater treatment, created wetland, habitat fragmentation","lastPublishedDoi":"10.21203/rs.3.rs-8139631/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8139631/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eUrban coastal wetlands protect humans from sea-level rise while providing valuable habitat for wildlife. Degradation and loss of these wetlands threaten urban infrastructure including wastewater treatment facilities. Nature-based adaptive solutions, with the combined purposes of bioremediation, coastal defense, and habitat creation, are being tested to make communities safer and more resilient. The current research examines an experimental horizontal levee installed in 2015 at the Oro Loma Sanitary District in San Lorenzo, California, 5 years after installation. Using quadrat sampling, we compare succession of two plant assemblages \u0026ndash; a wet meadow and a riparian scrub community \u0026ndash; on an ecotone slope. We use the wet meadow assemblage to document the effects of fragmentation and dominant plant species on plant diversity and abundance. Although most planted species survived from 2015 to 2021, plant diversity decreased over time in both communities. Fragmentation was associated with encroachment by a native dominant willow (\u003cem\u003eSalix lasiolepis)\u003c/em\u003e and an invasive nonnative jubatagrass (\u003cem\u003eCortaderia jubata)\u003c/em\u003e in the wet meadow. Both fragmentation and the presence of the willow or cattails (\u003cem\u003eTypha\u003c/em\u003e) correlated with reduced native species diversity and cover. In the absence of natural disturbance processes, created wetlands, especially fragmented wetlands with substantial edge, may progress to a successional state dominated by a few species. Future projects might benefit from specifying habitat creation goals in addition to wastewater treatment goals, selecting native plant assemblages that inhibit succession, planting larger patches, and incorporating natural or human disturbance to break dominance cycles.\u003c/p\u003e","manuscriptTitle":"Fragmentation Drives Dominant Plant Encroachment on a Horizontal Wastewater Treatment Levee","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-03 16:59:12","doi":"10.21203/rs.3.rs-8139631/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a9f80f8f-a486-4e94-9667-b1b6b4a0bdf5","owner":[],"postedDate":"December 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-03T05:23:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-03 16:59:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8139631","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8139631","identity":"rs-8139631","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}