Hydrological and edaphic filters structure early plant community assembly in Amazonian floodplain forests

Hydrological and edaphic filters structure early plant community assembly in Amazonian floodplain forests | 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 Hydrological and edaphic filters structure early plant community assembly in Amazonian floodplain forests Maiara Cunha Soares, Pia Parolin, Darley Calderaro Leal Matos, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9368458/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract In the Amazon, floodplain vegetation comprises extensive ecosystems whose ecological dynamics tied to the seasonal fluctuations in river levels. These transitional environments, known as igapó and várzea, serve as interfaces between aquatic and terrestrial systems, exhibiting distinct variations in species diversity, structural composition, and ecological functions. Igapó vegetation dominates regions with low soil fertility, occurring along blackwater and clearwater rivers, whereas várzea vegetation is found in areas influenced by whitewater rivers, rich in sediments and nutrients. The objective of this study was to compare the abundance of life forms involved in natural regeneration across igapó and várzea forests. The research was conducted at the Caxiuanã National Forest, Brazil. Six distinct life forms were identified within these flooded forests, with trees (37.8%), palms (35.6%), and herbaceous plants (14%) being the most prominent. A pronounced distinction in natural regeneration patterns was observed between the two forest types: igapó plots were predominantly dominated by herbaceous plants, while várzea plots displayed greater recruitment of arboreal species, palms, and epiphytes. This gradient of regeneration reflects not only the soil and water conditions of each forest type but also their role in maintaining distinct ecological processes. Understanding the dynamics of natural regeneration in floodplain forests is vital, given their essential role in regulating hydrological cycles, preventing soil erosion, and supporting biodiversity. The distribution of species in both igapó and várzea forests highlight their critical role in sustaining these dynamic ecosystems, which are indispensable for a variety of plant and animal species. Amazonian flood forests igapó natural regeneration várzea Figures Figure 1 Figure 2 Figure 3 Introduction In the Amazon biome, floodplain vegetation consists of widely distributed ecosystems whose ecological characteristics are closely related to seasonal variations in river levels. These transitional environments between the aquatic and terrestrial systems, known as igapó and várzea vegetation, exhibit distinct patterns of diversity, structure, and species composition. The differences are influenced by the amplitude and duration of floods and the nature of the soils and waters (Junk 1997 ). Igapó vegetation is predominant in regions where the soil is characterized by low fertility and sandy texture. They occur mainly in areas of blackwater or clearwater rivers, with soils poor in nutrients and rich in decomposing organic matter. In contrast, várzea vegetation is located in areas of whitewater rivers, rich in sediments and nutrients. These more fertile environments, with more recent soils and intense hydrological dynamics, favor the presence of a vegetation community with greater diversity and abundance of species (Wittmann et al. 2010 ). Flooding dynamics limit the development of woody species and favor the presence of plants with life forms that are adapted to water excess conditions (Ferreira et al. 2013 ). Several studies have shown different results in comparing the patterns of abundance of individuals, richness, diversity, and species composition among the types of flooded vegetation in the Amazon (Worbes 1997 ; Ferreira and Stohlgren 1999 ). However, we must take into account that these comparisons can only be made if the physical parameters that influence the distribution of biodiversity in the flooded vegetation of the Amazon are standardized (Albernaz 2008 ). Some studies show that the number of species in flooded várzea vegetation is higher compared to igapó vegetation (Wittmann et al. 2010 ). Others show the opposite pattern (Pinheiro and Ferreira 2022 ; Ferreira et al. 2023 ), and some do not display differences between the types of vegetation (Ferreira 1997 ). Regarding species composition, there is a consensus in the literature that the flooded vegetation of the Amazon is very distinct depending on the river system and valley (Haugaasen and Peres 2006 ; Wittmann et al. 2010 ; Ferreira et al. 2013 ). However, most studies that address floristic differences between igapó and várzea vegetation in the Amazon have been carried out at the community level of the tree stratum, with a diameter at breast height (DBH) equal to or greater than 10 cm (Ferreira et al. 2023 ). A focus on the natural regeneration, with smaller DBH, is important as it is a fundamental component of the ecological succession of floodplain forests. The regeneration is influenced by several factors, including the availability of light, nutrients, and the duration of flooding. We found a unique opportunity to investigate how distinct conditions affect species composition in different life forms such as trees, shrubs, herbaceous plants, vines, and palms in the Brazilian Caxiuanã National Forest, located in the State of Pará, in Eastern Amazonia. Here, igapó and várzea vegetation are well represented and the systems show the typical contrasting conditions of fertility, hydrological dynamics, and nutrient availability. Our aim was to answer the following question: do the composition and abundance of life forms in natural regeneration differ significantly between várzea and igapó forests in the Caxiuanã National Forest? Considering that the mentioned factors conditions of fertility, hydrological dynamics, and nutrient availability directly influence natural regeneration processes, we hypothesize that várzea forests exhibit greater species richness in natural regeneration, with a predominance of trees and palms, while igapó forests are dominated by herbaceous forms adapted to poor soils and prolonged flooding. By focusing on natural regeneration, this work aims to fill a gap in the literature by exploring how the edaphic and hydrological conditions of these forests influence ecological succession in an integrated way. We considered a wider range of life forms than most previous studies, which were limited to the tree stratum. The comparison between these two types of flooded vegetation will allow for a deeper understanding of the ecological processes and survival and establishment strategies of plants in these environments. Methods Study area The study was conducted at the Ferreira Penna Scientific Station (ECFPn), located in the Caxiuanã National Forest (FLONA), in the state of Pará, Brazil. The Caxiuanã FLONA covers approximately 330,000 hectares and is located in the municipalities of Portel and Melgaço in the northeastern region of Eastern Amazonia (Fig. 1 ). The climate is classified as hot tropical (Am) according to the Köppen classification, with an average annual temperature of around 26°C and an average relative humidity of 87% (Costa et al. 2010 ). The Caxiuanã FLONA region, particularly the Caxiuanã Bay area, is subject to significant natural disturbances caused by strong winds. These are formed by convective clouds that can reach speeds exceeding 80 km/h (Ataide et al. 2022 ). The flood season for the rivers and lakes in the region occurs between January and June, while the low water season is between July and December, with daily variations caused by the tide ranging from around 30 cm in the level of the main rivers in the interfluves to more than one meter in the Caxiuanã Bay. The main types of vegetation in the ECFPn are represented by the dense lowland rainforest (terra firme forest), secondary forests of different ages, and two types of flooded vegetation (igapós and várzeas) (Veloso et al. 1991 ). The igapó vegetation, located mainly in the interfluves of the rivers, is seasonally flooded by the annual fluctuation of the blackwater rivers and streams, as well as by daily tidal flooding. The forest canopy is closed, the trees have a small diameter, few palm species, and rich understory vegetation, characterized by a great abundance of herbaceous species (Ferreira et al. 2013 , Fig. 2 ). The soils of the igapó forests are classified as Gleysols with a silty texture, with poor drainage and in conditions of excess moisture, poor in nutrients and fragile (Pinheiro and Ferreira 2022 ). The várzea vegetation is mainly located in the Caxiuanã bay and is flooded by rivers with a higher sediment load. The forest canopy is more open, the trees have large diameters, with a high abundance of palms and vines (Ferreira et al. 2013 , Fig. 2 ). The soils are classified as Plinthosols, mineral soils formed under conditions of restricted water percolation, subject to the temporary effect of excess moisture, poorly drained, and with a higher proportion of nutrients (Pinheiro and Ferreira 2022 ). Data collection Data were collected in November 2019, during the period of low rainfall and low river levels, which allowed access to several flooded areas. Twenty plots were randomly distributed in each type of forest (várzea and igapó), measuring 2 x 2 meters. The plots were established on litter substrate, without surface water accumulation, and all at the same topographic elevation of the river. The minimum distance between plots varied from 300 to 500 meters to reduce the risk of spatial autocorrelation, to ensure independence between plots. Within each plot, all individuals were identified in the field and, in case of doubt, collected for later identification at the Herbarium of the Museu Paraense Emílio Goeldi (MG). The individuals were divided in relation to the life forms of trees, shrubs, herbaceous plants, vines, and palms (Flora and Funga of Brazil 2026). The species classification system adopted was APG IV (2016), and name validation was based on the Species List of the Flora do Brazil website (Flora and Funga of Brazil 2026). Data Analysis For data analysis, Principal Component Analysis (PCA) was used, allowing for the comparison of relationships between the abundance of various life forms in the vegetation - trees, shrubs, herbaceous plants, vines, epiphytes, and palms - in the igapó and várzea forests. An Indicator Species (IndVal) analysis was used to identify species that characterize sample groups (flooded forests types) based on their specificity (exclusiveness to the group) and fidelity (frequency within the group) (Dufrêne and Legendre 1997 ). The analysis was performed in the R statistical program (R Core Team, 2021 ) using the vegan and ggplot2 libraries (Oksanen et al. 2020 ). PCA was performed based on a variance-covariance matrix (Dolédec and Chessel 1994 ). The analysis was conducted using Past software (version 4.12) (Hammer et al. 2001 ), with the principal axes used to identify gradients of structural variation and differences in the composition of natural regeneration between the two vegetation types. Results A total of 1,185 individuals were sampled, 619 in the várzea forest and 566 in the igapó forest. Seventy-seven species were identified, 50 species in the várzea forest and 47 in the igapó forest, with only 20 species (26%) common to both flooded forests (supplementary material). Six life forms were identified in the two flooded forests, with trees (37.8%), palms (35.6%) and herbaceous plants (14%) being the most abundant (Table 1 ). There was a large difference in the abundance of life forms between the two types of flooded forests. Herbaceous and arboreal life forms, at 80.4% and 31.9%, respectively, were most abundant in igapó forests. The fern Trichomanes pinnatum Hedw. of the Hymenophyllaceae family was the most abundant species in this type of vegetation (Table 2 ). In várzea forests, plants with epiphytic (100%), palm (99.8%), and arboreal life forms (68.1%) were the most abundant (Table 1 ). Plants with palm-like life forms were represented by only three species, of which Euterpe oleracea Mart., clump-forming açaí palm, and Mauritia flexuosa L.f., buriti palm, accountede for almost 100% of the individuals, which are absent in the igapó forests (Table 2 ). Table 1 Abundance of life forms by type of flooded forest in várzea and igapó forests in the Ferreira Penna Scientific Station, Caxiuanã National Forest, Pará, Brazil Life form Total Igapó forest Várzea forest N ind % ind N ind % ind N ind % ind Tree 448 37,8 143 31,9 305 68,1 Shrub 11 0,9 3 0,7 8 99,3 Epiphyte 32 2,7 32 100,0 Herb 166 14,0 360 80,4 62 19,6 Palm 422 35,6 1 0,2 165 99,8 Vine 106 8,9 59 13,2 47 86,8 Ten species accounted for a large part of the total abundance of individuals in the two forests, ranging from 65.8% to 72.1%, between the igapó and várzea forests, respectively. Only Macrolobium angustifolium (Benth.) R.S.Cowan (Fabaceae) was common to both types of forests (Table 2 ). Nine of the 10 most abundant species in the várzea forests were trees and palms as life forms. The clump-forming açaí palm and the buriti palm were absent in the igapó forests (Table 2 ). In igapó forests, the most abundant species had herbaceous life forms, including the angiosperm families Araceae, Cyperaceae, Marantaceae, and Rapateaceae, and a fern, Tpinnatum , the most abundant species in this type of vegetation (Table 2 ). Table 2 Comparison of the most abundant species in várzea and igapó forests in the Ferreira Penna Scientific Station, Caxiuanã National Forest, Pará, Brazil Várzea forest Scientific name Family Life form N ind % ind Euterpe oleracea Mart. Arecaceae Palm 114 18,4 Virola surinamensis (Rol. ex Rottb.) Warb. Myristicaceae Tree 79 12,8 Cynometra bauhiniifolia Benth. Fabaceae Tree 54 8,7 Mauritia flexuosa L.f. Arecaceae Palm 50 8,1 Macrolobium angustifolium (Benth.) R.S.Cowan, Fabaceae Tree 34 5,5 Montrichardia linifera (Arruda) Schott Araceae Palm 29 4,7 Pterocarpus santalinoides L Hér. ex DC. LCides Fabaceae Tree 26 4,2 Zygia ramiflora (Benth.) Barneby & J.W.Grimes Fabaceae Tree 25 4 Philodendron muricatum Willd. ex Schott. Araceae Tree 22 3,6 Doliocarpus dentatus (Aubl.) Standl. Dilleniaceae Vine 13 2,1 TOTAL 446 72,1 Igapó forest Scientific name Family Life form N ind % ind Trichomanes pinnatum Hedw. Heminophyllaceae Herb 105 25,8 Montrichardia arborescens (L.) Schott. Araceae Herb 79 19,4 Rapatea paludosa Aubl. Rapateaceae Herb 60 14,7 Bredemeyera Willd. Cyperaceae Herb 47 11,5 Ischnosiphon polyphyllus Marantaceae Herb 28 6,9 Caraipa grandifolia Mart. Clusiaceae Tree 20 4,9 Rhynchospora pubera (Vahl) Boeckeler Cyperaceae Herb 20 4,9 Erisma uncinatum Warm Vochysiaceae Tree 19 4,7 Macrolobium angustifolium (Benth.) R.S.Cowan, Fabaceae Tree 15 3,7 Swartzia acuminata Willd. ex Vogel. Fabaceae Tree 14 3,4 TOTAL 407 65,8 Eighteen species were considered indicators of flooded environments according to the Indicator Species Analysis (IndVal), 9 species in the igapó forest, with emphasis on the herbaceous species, Montrichardia arborescens (L.) Schott. (r = 0.98; p = 0.001), Trichomanes pinnatum Hedw. (r = 0.84; p = 0.001) and Becquerelia sp, (r = 0.78; p = 0.001), while in the várzea forests, the highlights are the palm species, Euterpe oleracea Mart. (r = 0.87; p = 0.001) and two species with arboreal life form, Zygia ramiflora (Benth.) Barneby & J.W.Grimes (r = 0.74; p = 0.001) and Virola surinamensis (Rol. ex Rottb.) Warb. (r = 0.72; p = 0.001) (Table 3 ). Table 3 Species Indicators of flooded environments according to the Indicator Species Analysis (IndVal) in várzea and igapó forests in the Ferreira Penna Scientific Station, Caxiuanã National Forest, Pará, Brazil Forest type Scientific names Family Life forms r p Igapó Montrichardia arborescens . (L.) Schott. Araceae Herb 0.98 0.001 Igapó Trichomanes pinnatum Hedw. Heminophyllaceae Herb 0.84 0.001 Igapó Bredemeyera Willd. Cyperaceae Herb 0.78 0.001 Igapó Rapatea paludo sa Aubl. Rapataceae Herb 0.78 0.001 Igapó Caraipa grandifolia Mart. Clusiaceae Tree 0.58 0.043 Igapó Erisma uncinatum Warm Vochysiaceae Tree 0.55 0.024 Igapó Machaerium Pers. sp 2 Fabaceae Tree 0.55 0.019 Igapó Olyra L. Poaceae Herb 0.55 0.023 Igapó Rhynchospora pubera (Vahl) Boeckeler Cyperaceae Herb 0.50 0.043 Várzea Euterpe oleracea Mart. Arecaceae Palm 0.87 0.001 Várzea Zygia ramiflora (Benth.) Barneby & J.W.Grimes Fabaceae Tree 0.74 0.001 Várzea Virola surinamensis (Rol. ex Rottb.) Warb. Myristicaceae Tree 0.72 0.026 Várzea Pterocarpus santalinoides L Hér. ex DC. LC Fabaceae Tree 0.70 0.013 Várzea Mauritia flexuosa L.f. Arecaceae Palm 0.67 0.002 Várzea Philodendron muricatum Willd. ex Schott. Araceae Herb 0.67 0.003 Várzea Cynometra bauhiniifoli a Benth. Fabaceae Tree 0.63 0.001 Várzea Montrichardia linifera (Arruda) Schott Araceae Herb 0.63 0.004 Várzea Erisma calcaratum (Link) Warm. Vochysiaceae Tree 0.55 0.022 The principal component analysis (PCA) of natural regeneration revealed a clear separation between the igapó and várzea forest plots along the first axis. It explained 56.5% of the total data variation, while the second axis explained 27.6% of the variation, fundamental to understanding the internal dynamics of the várzea (Fig. 3 ). The axes clearly show a structural gradient of regeneration, ranging from plots dominated by herbaceous plants in igapó forests (negative extreme) to plots with greater recruitment of arboreal individuals, palms, and epiphytes (positive extreme) in várzea plots (Fig. 3 ). Discussion The comparison between igapó and várzea forests at the Ferreira Penna Scientific Station revealed striking differences in the composition and abundance of species in natural regeneration. We can attribute this to a combination of edaphic, hydrological, and structural factors. The igapó forest plots were predominantly associated with herbaceous plants, evidencing a limitation in the establishment of woody, but nutrient-dependent, life forms. This pattern is consistent with the more restrictive environmental conditions of this environment, characterized by acidic soils, poor in nutrients such as H + Al, Al, coarse sand, silt, and N% (Pinheiro and Ferreira 2022 ), in addition to being more shaded and subject to a generally more prolonged flooding regime. These conditions may act as environmental filters, reducing the abundance and growth of tree species and favoring herbaceous species with short life cycles, adapted to oligotrophic soils and hydrological stress (Ferreira et al. 2010 ). Studies on plant regeneration and reproduction in floodplain forests indicate that environments subject to prolonged flooding and low fertility restrict the establishment of long-life cycle plants, such as trees, favoring herbaceous or fast-cycle forms (Ferreira et al. 2010 ). This environmental filtering mechanism is supported by the results of Muscarella et al. ( 2019 ), who demonstrated that edaphic gradients and the flooding regime play a central role in structuring Amazonian plant communities. According to these authors, environments with greater hydrological stress and lower fertility tend to have more clustered communities, either functionally or phylogenetically, indicating that only a restricted set of ecological strategies can persist under such conditions. This pattern is consistent with the predominance of igapó plots dominated by herbaceous plants, as observed in the analysis. In contrast, the várzea plots showed a more structured regeneration, with a greater contribution from trees and palms. This reflects the greater fertility of these environments, fed by whitewater rivers rich in sediments. Factors such as pH, Mn, Fine Sand, K, Fe, Ca + Mg, Ca, Zn, play a crucial role in structuring the plant communities of natural regeneration in this environment (Pinheiro and Ferreira 2022 ). Under these conditions, the environmental filter is less severe, allowing the establishment and coexistence of woody life forms with different ecological strategies, resulting in greater structural complexity of regeneration. In addition, várzea forests are subjected to intensive wind action, which causes large movements in the waters of Caxiuanã Bay, resulting in mechanical damage to the plant community (Pinheiro 2014 ). This same phenomenon has already been cited for floodplain forests in western Amazonia (Haugaasen and Peres 2006 ) and in Central Amazonia (Ferreira et al. 2010 ). This high degree of disturbance results in a high annual mortality rate with annual rates of 1.8 ± 0.2, year − 1 in the Caxiuanã bay, which represents double the values ​​obtained in the igapó forests of the Curuá River, 0.9 ± 0.2%, year − 1 (Cunha 2018 ). These mortality rates are also higher than those recorded in terra firme forests in adjacent areas, in the Caxiuanã National Forest, ranging from 0.9% to 1.2% (Costa et al. 2010 ). One of the main consequences of this natural impact is the increased canopy opening in the várzea forests of the study region, which facilitates the establishment of plant dispersal propagules with arboreal and palm life forms that require large amounts of light and nutrient-rich soils for establishment and growth (Ferreira et al. 2013 ). The palm trees showed great abundance of clump-forming açaí seedlings ( Euterpe oleraceae Mart.) only in the natural regeneration plots of the várzea forests of Caxiuanã Bay. This is not surprising, since Ferreira et al. ( 2013 ) recorded 875 adult clump-forming açaí individuals, with diameters greater than 10 cm, in two permanent one-hectare vegetation plots planted in the floodplain forests of Caxiuanã Bay and only 10 adult individuals in 2 one-hectare plots in the igapó forests planted in the Curuá River. Several palm species are better competitors for nutrients in the fertile environments of flooded várzea forests in the Amazon basin, as already recorded in Amazonian estuaries. They are dominant in many flooded várzea forests in the states of Pará (Jardim and Vieira 2001 ) and Amapá (Carim 2016 ). The absence of these natural impacts on the vegetation of the igapó forests of the Curuá River, the area of ​​this study, allows for greater shading of the understory. This enhances shade-tolerant species from the herbaceous plant community to be the life forms with the greatest abundance of individuals, such as species from the angiosperm families Cyperaceae, Rapateaceae, Maranthaceae, among others, also recorded by Maciel-Silva et al. ( 2019 ) and Pinheiro and Ferreira ( 2022 ) in other interfluves of igapó forests of the Ferreira Scientific Station in Caxiuanã. The most abundant species in the flooded forests of the Curuá River, the terrestrial fern Trichomanes pinnatum Hedw (Hymenophyllaceae), is absent from the natural regeneration plots of the várzea forests of Caxiuanã Bay. Our hypothesis is that the larger canopy openings in the várzea forests may hinder the regeneration of this species, a situation that does not occur in the flooded forests of the river. Zuquim et al. ( 2007 ) report that in humid tropical forests, high humidity and shading are essential conditions for the development of ferns and lycophytes. Phillips et al. ( 2003 ) state that the predominant factor in floristic composition is the variation in soil types, and that edaphic correlation can explain about 90% of the variation in diversity found, while Souza et al. ( 2012 ) report that the distribution of species along a topographic gradient is associated with variations in chemical fertility, acidity, and soil texture. Furthermore, igapó forests with nutrient-poor soils tend to have greater species diversity because of greater competition for light, while várzea forests, richer in nutrients and with lower diversity, are consequences of better competition among trees for nutrients that excluded other forms of life (Matos 2018 ). Matos et al. ( 2018 ) recorded Macrolobium angustifolium (Benth.) R.S.Cowan as one of the common and abundant tree species among two igapó and várzea forests in the same area of this study and associated this with the species' capacity in relation to different combinations of functional attributes related to different levels of soil nutrients and light availability between the two types of flooded forests. In the várzea forests of Caxiuanã Bay, adult populations of this species have small leaves and individuals of low stature. This may suggest adaptations to take advantage of the greater canopy opening. In contrast, in the igapó forests of the Curuá River, the leaves are larger, with a greater leaf area, probably to maximize the capture of solar radiation that reaches the understory. This is a strategy to increase photosynthesis under conditions of more intense shade. Furthermore, Batista ( 2017 ) analyzed the functional traits of Swartzia acuminata Willd. ex Vogel (Fabaceae), another representative species of the region's floodplain forests. They observed that populations of this species showed significant differences in functional characteristics, such as leaf area and leaf dry matter content, between igapó and várzea forests, with higher values ​​in várzea forests. The principal component analysis (PCA) revealed a clear separation between the two forest types along the first axis, with the second axis explaining 27.6% of the variation. This is essential to understanding the internal dynamics of várzea forests. This axis indicates important variations in the composition of regeneration, especially related to the dominance of palms. The distinction between vegetation types suggests different successional trajectories and an influence of micro environmental conditions, such as variations in flood duration, topography, and resource availability. Plots located in the upper right portion of the graph showed a greater association with the tree habit, while others were strongly associated with palms, indicating an environmental gradient in regeneration. This internal separation within the set of floodplain plots indicates that this environment does not constitute a homogeneous unit from the point of view of natural regeneration. On the contrary, the distribution of plots along the second axis reflects the environmental and structural heterogeneity of the floodplains. This highlights the high carrying capacity of these areas for woody vegetation, as suggested by Muscarella et al. ( 2019 ). They demonstrated that fertility and flooding gradients promote strong differentiation in the composition and structure of plant communities in floodable Amazonian forests. The comparison between igapó and várzea forests provides new perspectives on the dynamics of ecological succession in these flooded ecosystems. This highlights how winds and environmental gradients (soil fertility, flooding regime, and light availability) shape the structure of plant communities. Our study reveals that, in igapó forests, natural regeneration is predominantly herbaceous, reflecting the more restrictive conditions of poor soil and prolonged flooding, while in várzea forests, the richer nutrient conditions favor a more structured regeneration, with a predominance of trees and palms. A deeper analysis of these functional plant strategies, considering the level of competition for light and nutrients and the microenvironmental conditions, is crucial to improve the understanding of the ecological processes that govern natural regeneration and functional diversity in these flooded ecosystems of the Amazon. Future research should consider not only edaphic and hydrological aspects, but also how biological and ecological variables interact to promote ecological succession and the permanence of plant communities in these dynamic environments. Conclusions This study contributes to the understanding of the ecological processes that shape the flooded forests of Eastern Amazonia. The differences observed in the natural regeneration of igapó and várzea forests, in terms of life forms and community structure, reveal the importance of edaphic and hydrological conditions in the formation of these plant communities. Igapó forests, with low-fertility soils and prolonged flooding regimes, were dominated by herbaceous species. Várzea forests, with higher fertility and a more dynamic hydrological regime, favored the establishment of trees and palms. Principal component analysis (PCA) was crucial to identify these differences and to understand how factors such as light and nutrient availability influence the structure of natural regeneration. By highlighting these variations, the study emphasizes the ecological complexity of flooded forests and the need to consider environmental heterogeneity in the management and conservation of these ecosystems. The ecological importance of understanding these processes is clear: floodplain forests play crucial roles in regulating water cycles, controlling soil erosion, and maintaining local biodiversity. These forests are important habitats for diverse plant and animal species, many of which are adapted to the specific conditions of each vegetation type. The preservation and effective management of these areas depend on a deep understanding of the environmental factors that determine the regeneration of plant communities, as well as the functional strategies that these species use to persist in environments with strong hydrological variation. Finally, the study proposes that the conservation and sustainable management of igapó and várzea forests should be based on ecological diversity and the specific conditions of each environment. It is important to take the importance of these forests into account for maintaining ecological services and biodiversity in the whole Amazon region. Statements & Declarations Acknowledgments This work was supported by Long-Term Research Program (PELD)/National Council for Scientific and Technological Development (CNPq), Process: 445593/2024-5 and for a Research Productivity Grant to the last author (Process 305469/2025-8). Funding This work was supported by Long-Term Research Program (PELD)/National Council for Scientific and Technological Development (CNPq), Grant: 445593/2024-5 and for a Research Productivity Grant to the last author (Process 305469/2025-8). Competing Interests The authors declare that there are no conflicts of interest regarding the research, authorship, and/or publication of this article. Author Contributions Conceptualisation was done by Maiara Cunha Soares; Field data collection was done by Leandro Valle Ferreira and Maiara Cunha Soares, and Methodology was designed by Leandro Ferreira and Priscila Sanjuan de Medeiros Sarmento. The first draft of the manuscript was written by Leandro Valle Ferreira and Maiara Cunha Soares. Previous versions of the manuscript were commented and Pia Parolin, Darley Calderaro Leal Matos, Marcilene da Silva Pinheiro and Mário Augusto Gonçalves Jardim. All authors read and approved the final manuscript. Data Availability The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. References Albernaz ALKM (2008) Conservação da várzea: Identificação e caracterização de regiões biogeográficas – IBAMA/ProVarzea, Manaus Angiosperm Phylogeny Group (2016) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society v.181, pp 1- 20 Ataide WLD, Oliveira FA, Braga CO, Amorim MB, Carneiro FS, Chagas GFB, Balma FB, Maestri MP (2022) Caracterización de los vientos sobre Flona Caxiuanã en el año de ENOS. Research, Society and Development 11:1-12. https://doi.org/10.33448/rsd-v11i1.22584 Batista AWS (2017) Estudos ecológicos de Swartzia polyphylla DC. (Fabaceae) em florestas inundáveis na Amazônia Oriental.Dissertação, Programa de Pós-Graduação em Botânica Tropical (UFRA/MPEG) Carim MJV (2016) Estrutura, composição e diversidade em florestas alagáveis de várzea de maré e de igapó e suas relações com variáveis edáficas e o período de inundação no Amapá, Amazônia Oriental, Brasil. Tese, Instituto Nacional de Pesquisas da Amazônia, Manaus Costa ACL, Galbraith D, Almeida S, Portela BTT, Costa M, Junior JAS, Braga AP, Gonçalves PHL, Oliveira AAR, Fisher R, Phillips OL, Metcalfe DB, Levy P, Meir P (2010) Effect of 7 yr of experimental drought on vegetation dynamics and biomass storage of an eastern Amazonian rain forest. New Phytologist 187:579–591. https://doi.org/10.1111/j.1469-8137.2010.03309.x Cunha DA (2018) Dinâmica e produtividade em florestas de igapó e várzea na Amazônia Oriental.Tese, Programa de Pós-graduação em Biodiversidade e Biotecnologia da Rede Bionorte Dolédec S, Chessel D (1994) Co-inertia analysis: aa alternative method for studying species: environment relationships. Freshwater Biology 31:277-294. https://doi.org/10.1111/j.1365-2427.1994.tb01741.s Dufrêne M, Legendre P (1997) Species assemblages and indicator species: the need for flexible asymmetrical approach. Ecological Monographs 67(3):345-366 Ferreira LV (1997) Effects of flooding duration of species richness and floristic composition in three hectares in the Jaú National Park in floodplain forests in central Amazonia. Biodiversity and Conservation 6:1353-1363 Ferreira LV, Almeida SS, Parolin P (2010) Amazonian white- and blackwater floodplain forests in Brazil: large differences on a small scale. Ecotropica 16:31-41 Ferreira, LV, Cunha DA, Chaves, PP, Matos, DCL, Parolin P (2013) Variação da riqueza e composição de espécies da comunidade de plantas entre as florestas de igapós e várzeas da Estação Científica Ferreira Penna-Caxiuanã na Amazônia Oriental. Pesquisas. Botânica 64:175-195 Ferreira LV, Maia APM, Pinheiro MS, Oliveira MC, Junior LEP, Amorim JTA, Baia LLF, Matos JHT, Jardim MAG (2023) Diversidade florística em fitofisionomias de duas unidades de conservação na Amazônia Oriental, Pará, brasil. Revista Brasileira de Geografia Física 16:3283-3297. https://doi.org/10.26848/rbgf.v16.6.p3283-3297 Ferreira CS, Piedade MTF, Wittmann AO, Franco AC (2010) Plant reproduction in the Central Amazonian floodplains: challenges and adaptations. AoB plants 2010:plq009. https://doi.org/10.1093/aobpla/plq009 Ferreira LV, Stohlgren TJ (1999) Effects of river level fluctuation on plant species richness, diversity, and distribution in a floodplain forest in central Amazonia. Oecologia 120:582-587. https://doi.org/10.1007/s004420050893 Flora e Funga do Brasil. Jardim Botânico do Rio de Janeiro. http://floradobrasil.jbrj.gov.br/. Acessado em 21 de janeiro de 2026 Hammer Ø, Harper DAT, Ryan PD (2001) PAST: Paleontological Statistics Software Package for Education and Data Analysis. Palaeontologia Electronica4:9. https://palaeo-electronica.org/2001_1/past/issue1_01.htm Haugaasen T, Peres CA (2006) Floristic, edaphic and structural characteristics of flooded and unflooded forests in the lower Rio Purús region of central Amazonia, Brazil. Acta Amazônica 36:25-36 Jardim MAG, Vieira ICG (2001) Composição florística e estrutura de uma floresta de várzea do estuário amazônico, ilha do Combu, Estado do Pará, Brasil. Boletim do Museu Paraense Emilio Goeldi - Série Botânica 17:333-354 Junk WJ (1997) General aspects of floodplain ecology with special reference to Amazonian floodplains. In: Junk WJ (ed). The Central Amazon Floodplain. Springer-Verlag, Berlin Heidelberg, pp 3-20 Maciel-Silva JF, Nunes CS, Ferreira LV, Bragança Gil AS (2019) Cyperaceae aquáticas e palustres na Floresta Nacional de Caxiuanã, Pará, Amazônia, Brasil. Boletim do Museu Paraense Emílio Goeldi - Ciências Naturais 14:391-424 Matos DCL (2018) Diversidade funcional da comunidade de árvores em florestas inundadas na Amazônia Oriental.Tese, Programa de Pós-graduação em Biodiversidade e Biotecnologia da Rede Bionorte Matos DCL, Ferreira LV, Carlucci MB (2018) Estratégias funcionais de Macrolobium angustifolium (Benth.) R.S.Cowan para coexistir em florestas inundadas na Amazônia oriental. Revista Spacios 39:1-16 Muscarella R, Bacon CD, Faurby S, Antonelli A, Kristiansen SM, Svenning JC, Balslev H (2019) Soil fertility and flood regime are correlated with phylogenetic structure of Amazonian palm communities. Annals of Botany 123:641-655. https://doi.org/10.1093/aob/mcy196 Oksanen, J et al Vegan (2020) Community Ecology Package. R package version Phillips OL, Vargas PN, Monteagudo AL, Cruz AP, Zans MEC, Sánchez WG, Yli-Halla M, Rose S (2003) Habitat association among Amazonian tree species: a landscape scale approach. Journal of Ecology 91:757-775. https://doi.org/10.1046/j.1365-2745.2003.00815.x Pinheiro NA (2014) Balanço de energia e fluxos turbulentos associados à fatores físicoquímicos da água na baía de Caxiuanã. Dissertação, Programa de Pós-Graduação em Ciências Ambientais - Universidade Federal do Pará, EMBRAPA Amazônia Oriental, Museu Paraense Emilio Goeldi Pinheiro MS, Ferreira LV (2022) Florística e estrutura de florestas inundadas na Floresta Nacional de Caxiuanã, Pará, Brasil. Nature and Conservation 15:1-16. https://doi.org/10.6008/CBPC2318-2881.2022.003.0001 R Core Team (2021) A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/ Souza PB, Lelis JJ, Schaefer CEGR, Souza AL, Meira Neto JAA (2012) Distribution of tree species in a geomorphological and pedological gradient of submontane semidecidual seasonal forest in the vicinity of Rio Doce State Park, Minas Gerais. Revista Árvore 36:707-718. https://doi.org/10.1590/S0100-67622012000400012 Veloso HP, Rangel Filho ALR, Lima JCA (1991) Classificação da Vegetação Brasileira, adaptada a um sistema universal. IBGE, Rio de Janeiro Wittmann F, Junk WJ, Schongart J (2010) Phytogeography, species diversity, community structure and dynamics of central Amazonian floodplain forests. In: Junk WJ et al. (Eds), Central Amazonian Floodplain Forests: Ecophysiology, Biodiversity and Sustainable Management, Ecological Studies, Springer Verlag, pp 61-102. https://doi.org/10.1007/978-90-481-8725-6_4 Worbes M (1997) The forest ecosystem of the floodplains. In: The Central Amazon floodplain: Ecology of a pulsing system. Berlin, Heidelberg: Springer Berlin Heidelberg 126:223-265 Zuquim G, Costa FRC, Prado J (2007) Fatores que determinam a distribuição de espécies de pteridófitas da Amazônia Central. Revista Brasileira de Biociências 5:360-362. https://seer.ufrgs.br/index.php/rbrasbioci/article/view/115114 Supplementary Files SupplementaryMaterial.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 08 May, 2026 Reviewers invited by journal 07 May, 2026 Editor invited by journal 06 May, 2026 Editor assigned by journal 06 May, 2026 First submitted to journal 05 May, 2026 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-9368458","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":636266336,"identity":"c1cc690d-23c9-475f-a0ac-14af224aa387","order_by":0,"name":"Maiara Cunha Soares","email":"","orcid":"https://orcid.org/0009-0003-1717-2888","institution":"Museu Paraense Emílio Goeldi: Museu Paraense Emilio Goeldi","correspondingAuthor":false,"prefix":"","firstName":"Maiara","middleName":"Cunha","lastName":"Soares","suffix":""},{"id":636266337,"identity":"fce87d06-4841-40b1-ba77-ba3a502d755e","order_by":1,"name":"Pia Parolin","email":"","orcid":"","institution":"Max Planck Institute of Animal Behavior: Max-Planck-Institut fur Verhaltensbiologie","correspondingAuthor":false,"prefix":"","firstName":"Pia","middleName":"","lastName":"Parolin","suffix":""},{"id":636266338,"identity":"094610a8-5faa-4a02-99b4-d8a270aec12f","order_by":2,"name":"Darley Calderaro Leal Matos","email":"","orcid":"","institution":"Instituto Federal de Educacao Ciencia e Tecnologia do Amapa","correspondingAuthor":false,"prefix":"","firstName":"Darley","middleName":"Calderaro Leal","lastName":"Matos","suffix":""},{"id":636266339,"identity":"73c70384-209d-4960-905f-1bc9242d9252","order_by":3,"name":"Marcilene da Silva Pinheiro","email":"","orcid":"","institution":"Museu Paraense Emílio Goeldi: Museu Paraense Emilio Goeldi","correspondingAuthor":false,"prefix":"","firstName":"Marcilene","middleName":"da Silva","lastName":"Pinheiro","suffix":""},{"id":636266340,"identity":"131bd8bd-f688-4bbc-bb66-0d1411d875b0","order_by":4,"name":"Priscila Sanjuan de Medeiros Sarmento","email":"","orcid":"","institution":"Instituto Tecnológico Vale: Instituto Tecnologico Vale Desenvolvimento Sustentavel","correspondingAuthor":false,"prefix":"","firstName":"Priscila","middleName":"Sanjuan de Medeiros","lastName":"Sarmento","suffix":""},{"id":636266341,"identity":"9a453136-7982-4f66-8905-ced77f2a4c44","order_by":5,"name":"Mario Augusto Gonçalves Jardim","email":"","orcid":"","institution":"Museu Paraense Emílio Goeldi: Museu Paraense Emilio Goeldi","correspondingAuthor":false,"prefix":"","firstName":"Mario","middleName":"Augusto Gonçalves","lastName":"Jardim","suffix":""},{"id":636266342,"identity":"1914fd5a-b06b-440b-a445-0e81df26c9dc","order_by":6,"name":"Leandro Valle Ferreira","email":"","orcid":"","institution":"Museu Paraense Emílio Goeldi: Museu Paraense Emilio Goeldi","correspondingAuthor":false,"prefix":"","firstName":"Leandro","middleName":"Valle","lastName":"Ferreira","suffix":""}],"badges":[],"createdAt":"2026-04-09 12:18:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9368458/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9368458/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109438574,"identity":"048ac1cd-84ea-4923-9079-01f77483dc29","added_by":"auto","created_at":"2026-05-18 06:45:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":401395,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of the Ferreira Penna Scientific Station (ECFPn) in the Caxiuanã National Forest, Pará, Brazil\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9368458/v1/dbcd40d19a3527900e59b6fd.png"},{"id":109800392,"identity":"5d8cd73a-b247-4bbe-852a-7b44adb58af6","added_by":"auto","created_at":"2026-05-22 15:37:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":554445,"visible":true,"origin":"","legend":"\u003cp\u003eVegetation structure of the igapó forest of the Curuá River (A); interior view of the lateral flooding of the igapó of the Curuá River (B); partially flooded understory of the igapó of the Curuá River (C); vegetation structure of the várzea forest of the Caxiuanã Bay, showing the large quantity of aquatic macrophytes (D); partial view of the margin of the várzeas of the Caxiuanã Bay, with buriti palms (E) and partially flooded understory of the várzea of ​​the Caxiuanã Bay (F)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9368458/v1/8b0963d91de9cd6a83ed90d8.png"},{"id":109759409,"identity":"50b6765b-9daa-4e07-b644-3a29ddbdae54","added_by":"auto","created_at":"2026-05-22 07:26:58","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":102279,"visible":true,"origin":"","legend":"\u003cp\u003ePrincipal Component Analysis (PCA) of the vegetation in natural regeneration in igapó (IG) and várzea (VA) forests, based on the abundance of individuals by life form (tree, shrub, herbaceous, vine, epiphytic and palm) per plot\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9368458/v1/9c267d0c80ebe47a4b4eb248.png"},{"id":109907156,"identity":"90682f36-e14b-4b77-88e9-ba3a7df9c61d","added_by":"auto","created_at":"2026-05-25 06:41:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1366884,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9368458/v1/7cea44e9-6436-4103-880d-4b0e6c57e6cc.pdf"},{"id":109438577,"identity":"8cd31169-72ef-44b1-8bad-b854fbdab46c","added_by":"auto","created_at":"2026-05-18 06:45:24","extension":"docx","order_by":11,"title":"","display":"","copyAsset":false,"role":"supplement","size":20283,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-9368458/v1/d4ff86aa909eb97f3adea98f.docx"}],"financialInterests":"","formattedTitle":"\u003cp\u003eHydrological and edaphic filters structure early plant community assembly in Amazonian floodplain forests\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn the Amazon biome, floodplain vegetation consists of widely distributed ecosystems whose ecological characteristics are closely related to seasonal variations in river levels. These transitional environments between the aquatic and terrestrial systems, known as igap\u0026oacute; and v\u0026aacute;rzea vegetation, exhibit distinct patterns of diversity, structure, and species composition. The differences are influenced by the amplitude and duration of floods and the nature of the soils and waters (Junk \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1997\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cem\u003eIgap\u0026oacute; vegetation\u003c/em\u003e is predominant in regions where the soil is characterized by low fertility and sandy texture. They occur mainly in areas of blackwater or clearwater rivers, with soils poor in nutrients and rich in decomposing organic matter. In contrast, \u003cem\u003ev\u0026aacute;rzea vegetation\u003c/em\u003e is located in areas of whitewater rivers, rich in sediments and nutrients. These more fertile environments, with more recent soils and intense hydrological dynamics, favor the presence of a vegetation community with greater diversity and abundance of species (Wittmann et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFlooding dynamics limit the development of woody species and favor the presence of plants with life forms that are adapted to water excess conditions (Ferreira et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral studies have shown different results in comparing the patterns of abundance of individuals, richness, diversity, and species composition among the types of flooded vegetation in the Amazon (Worbes \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Ferreira and Stohlgren \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1999\u003c/span\u003e). However, we must take into account that these comparisons can only be made if the physical parameters that influence the distribution of biodiversity in the flooded vegetation of the Amazon are standardized (Albernaz \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSome studies show that the number of species in flooded v\u0026aacute;rzea vegetation is higher compared to igap\u0026oacute; vegetation (Wittmann et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Others show the opposite pattern (Pinheiro and Ferreira \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Ferreira et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and some do not display differences between the types of vegetation (Ferreira \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). Regarding species composition, there is a consensus in the literature that the flooded vegetation of the Amazon is very distinct depending on the river system and valley (Haugaasen and Peres \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Wittmann et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Ferreira et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). However, most studies that address floristic differences between igap\u0026oacute; and v\u0026aacute;rzea vegetation in the Amazon have been carried out at the community level of the tree stratum, with a diameter at breast height (DBH) equal to or greater than 10 cm (Ferreira et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA focus on the natural regeneration, with smaller DBH, is important as it is a fundamental component of the ecological succession of floodplain forests. The regeneration is influenced by several factors, including the availability of light, nutrients, and the duration of flooding. We found a unique opportunity to investigate how distinct conditions affect species composition in different life forms such as trees, shrubs, herbaceous plants, vines, and palms in the Brazilian Caxiuan\u0026atilde; National Forest, located in the State of Par\u0026aacute;, in Eastern Amazonia. Here, igap\u0026oacute; and v\u0026aacute;rzea vegetation are well represented and the systems show the typical contrasting conditions of fertility, hydrological dynamics, and nutrient availability.\u003c/p\u003e \u003cp\u003eOur aim was to answer the following question: do the composition and abundance of life forms in natural regeneration differ significantly between v\u0026aacute;rzea and igap\u0026oacute; forests in the Caxiuan\u0026atilde; National Forest? Considering that the mentioned factors conditions of fertility, hydrological dynamics, and nutrient availability directly influence natural regeneration processes, we hypothesize that v\u0026aacute;rzea forests exhibit greater species richness in natural regeneration, with a predominance of trees and palms, while igap\u0026oacute; forests are dominated by herbaceous forms adapted to poor soils and prolonged flooding.\u003c/p\u003e \u003cp\u003eBy focusing on natural regeneration, this work aims to fill a gap in the literature by exploring how the edaphic and hydrological conditions of these forests influence ecological succession in an integrated way. We considered a wider range of life forms than most previous studies, which were limited to the tree stratum. The comparison between these two types of flooded vegetation will allow for a deeper understanding of the ecological processes and survival and establishment strategies of plants in these environments.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy area\u003c/h2\u003e \u003cp\u003eThe study was conducted at the Ferreira Penna Scientific Station (ECFPn), located in the Caxiuan\u0026atilde; National Forest (FLONA), in the state of Par\u0026aacute;, Brazil. The Caxiuan\u0026atilde; FLONA covers approximately 330,000 hectares and is located in the municipalities of Portel and Melga\u0026ccedil;o in the northeastern region of Eastern Amazonia (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The climate is classified as hot tropical (Am) according to the K\u0026ouml;ppen classification, with an average annual temperature of around 26\u0026deg;C and an average relative humidity of 87% (Costa et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe Caxiuan\u0026atilde; FLONA region, particularly the Caxiuan\u0026atilde; Bay area, is subject to significant natural disturbances caused by strong winds. These are formed by convective clouds that can reach speeds exceeding 80 km/h (Ataide et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The flood season for the rivers and lakes in the region occurs between January and June, while the low water season is between July and December, with daily variations caused by the tide ranging from around 30 cm in the level of the main rivers in the interfluves to more than one meter in the Caxiuan\u0026atilde; Bay.\u003c/p\u003e \u003cp\u003eThe main types of vegetation in the ECFPn are represented by the dense lowland rainforest (terra firme forest), secondary forests of different ages, and two types of flooded vegetation (igap\u0026oacute;s and v\u0026aacute;rzeas) (Veloso et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1991\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe igap\u0026oacute; vegetation, located mainly in the interfluves of the rivers, is seasonally flooded by the annual fluctuation of the blackwater rivers and streams, as well as by daily tidal flooding. The forest canopy is closed, the trees have a small diameter, few palm species, and rich understory vegetation, characterized by a great abundance of herbaceous species (Ferreira et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The soils of the igap\u0026oacute; forests are classified as Gleysols with a silty texture, with poor drainage and in conditions of excess moisture, poor in nutrients and fragile (Pinheiro and Ferreira \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe v\u0026aacute;rzea vegetation is mainly located in the Caxiuan\u0026atilde; bay and is flooded by rivers with a higher sediment load. The forest canopy is more open, the trees have large diameters, with a high abundance of palms and vines (Ferreira et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The soils are classified as Plinthosols, mineral soils formed under conditions of restricted water percolation, subject to the temporary effect of excess moisture, poorly drained, and with a higher proportion of nutrients (Pinheiro and Ferreira \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData collection\u003c/h3\u003e\n\u003cp\u003eData were collected in November 2019, during the period of low rainfall and low river levels, which allowed access to several flooded areas. Twenty plots were randomly distributed in each type of forest (v\u0026aacute;rzea and igap\u0026oacute;), measuring 2 x 2 meters. The plots were established on litter substrate, without surface water accumulation, and all at the same topographic elevation of the river. The minimum distance between plots varied from 300 to 500 meters to reduce the risk of spatial autocorrelation, to ensure independence between plots.\u003c/p\u003e \u003cp\u003eWithin each plot, all individuals were identified in the field and, in case of doubt, collected for later identification at the Herbarium of the Museu Paraense Em\u0026iacute;lio Goeldi (MG). The individuals were divided in relation to the life forms of trees, shrubs, herbaceous plants, vines, and palms (Flora and Funga of Brazil 2026). The species classification system adopted was APG IV (2016), and name validation was based on the Species List of the Flora do Brazil website (Flora and Funga of Brazil 2026).\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cp\u003eFor data analysis, Principal Component Analysis (PCA) was used, allowing for the comparison of relationships between the abundance of various life forms in the vegetation - trees, shrubs, herbaceous plants, vines, epiphytes, and palms - in the igap\u0026oacute; and v\u0026aacute;rzea forests.\u003c/p\u003e \u003cp\u003eAn Indicator Species (IndVal) analysis was used to identify species that characterize sample groups (flooded forests types) based on their specificity (exclusiveness to the group) and fidelity (frequency within the group) (Dufr\u0026ecirc;ne and Legendre \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). The analysis was performed in the R statistical program (R Core Team, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) using the vegan and ggplot2 libraries (Oksanen et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePCA was performed based on a variance-covariance matrix (Dol\u0026eacute;dec and Chessel \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1994\u003c/span\u003e). The analysis was conducted using Past software (version 4.12) (Hammer et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2001\u003c/span\u003e), with the principal axes used to identify gradients of structural variation and differences in the composition of natural regeneration between the two vegetation types.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 1,185 individuals were sampled, 619 in the v\u0026aacute;rzea forest and 566 in the igap\u0026oacute; forest. Seventy-seven species were identified, 50 species in the v\u0026aacute;rzea forest and 47 in the igap\u0026oacute; forest, with only 20 species (26%) common to both flooded forests (supplementary material).\u003c/p\u003e \u003cp\u003eSix life forms were identified in the two flooded forests, with trees (37.8%), palms (35.6%) and herbaceous plants (14%) being the most abundant (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). There was a large difference in the abundance of life forms between the two types of flooded forests. Herbaceous and arboreal life forms, at 80.4% and 31.9%, respectively, were most abundant in igap\u0026oacute; forests. The fern \u003cem\u003eTrichomanes pinnatum\u003c/em\u003e Hedw. of the Hymenophyllaceae family was the most abundant species in this type of vegetation (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn v\u0026aacute;rzea forests, plants with epiphytic (100%), palm (99.8%), and arboreal life forms (68.1%) were the most abundant (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Plants with palm-like life forms were represented by only three species, of which \u003cem\u003eEuterpe oleracea\u003c/em\u003e Mart., clump-forming a\u0026ccedil;a\u0026iacute; palm, and \u003cem\u003eMauritia flexuosa\u003c/em\u003e L.f., buriti palm, accountede for almost 100% of the individuals, which are absent in the igap\u0026oacute; forests (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAbundance of life forms by type of flooded forest in v\u0026aacute;rzea and igap\u0026oacute; forests in the Ferreira Penna Scientific Station, Caxiuan\u0026atilde; National Forest, Par\u0026aacute;, Brazil\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLife form\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eIgap\u0026oacute; forest\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eV\u0026aacute;rzea forest\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e% ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e% ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eN ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e% ind\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e448\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e37,8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e143\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e31,9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e68,1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eShrub\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0,9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e99,3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEpiphyte\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e100,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e166\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e360\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e80,4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e19,6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e422\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e35,6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e99,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e106\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8,9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13,2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e86,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTen species accounted for a large part of the total abundance of individuals in the two forests, ranging from 65.8% to 72.1%, between the igap\u0026oacute; and v\u0026aacute;rzea forests, respectively. Only \u003cem\u003eMacrolobium angustifolium\u003c/em\u003e (Benth.) R.S.Cowan (Fabaceae) was common to both types of forests (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNine of the 10 most abundant species in the v\u0026aacute;rzea forests were trees and palms as life forms. The clump-forming a\u0026ccedil;a\u0026iacute; palm and the buriti palm were absent in the igap\u0026oacute; forests (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn igap\u0026oacute; forests, the most abundant species had herbaceous life forms, including the angiosperm families Araceae, Cyperaceae, Marantaceae, and Rapateaceae, and a fern, \u003cem\u003eTpinnatum\u003c/em\u003e, the most abundant species in this type of vegetation (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the most abundant species in v\u0026aacute;rzea and igap\u0026oacute; forests in the Ferreira Penna Scientific Station, Caxiuan\u0026atilde; National Forest, Par\u0026aacute;, Brazil\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea forest\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScientific name\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFamily\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLife form\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN ind\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e% ind\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eEuterpe oleracea\u003c/em\u003e Mart.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArecaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18,4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eVirola surinamensis\u003c/em\u003e (Rol. ex Rottb.) Warb.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMyristicaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCynometra bauhiniifolia\u003c/em\u003e Benth.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMauritia flexuosa\u003c/em\u003e L.f.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArecaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8,1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMacrolobium angustifolium\u003c/em\u003e\u0026nbsp;(Benth.) R.S.Cowan,\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5,5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMontrichardia linifera\u003c/em\u003e (Arruda) Schott\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePterocarpus santalinoides\u003c/em\u003e L H\u0026eacute;r. ex DC. LCides\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4,2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eZygia ramiflora\u003c/em\u003e (Benth.) Barneby \u0026amp; J.W.Grimes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePhilodendron muricatum\u003c/em\u003e Willd. ex Schott.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3,6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eDoliocarpus dentatus\u003c/em\u003e (Aubl.) Standl.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDilleniaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2,1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTOTAL\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e446\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e72,1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIgap\u0026oacute; forest\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eScientific name\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFamily\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eLife form\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN ind\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e% ind\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTrichomanes pinnatum\u003c/em\u003e Hedw.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHeminophyllaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMontrichardia arborescens\u003c/em\u003e (L.) Schott.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19,4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eRapatea paludosa\u003c/em\u003e Aubl.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRapateaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBredemeyera Willd.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCyperaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11,5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eIschnosiphon polyphyllus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarantaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6,9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCaraipa grandifolia Mart.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClusiaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4,9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eRhynchospora pubera\u003c/em\u003e (Vahl) Boeckeler\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCyperaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4,9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eErisma uncinatum\u003c/em\u003e Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVochysiaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMacrolobium angustifolium\u003c/em\u003e\u0026nbsp;(Benth.) R.S.Cowan,\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSwartzia acuminata\u003c/em\u003e\u0026nbsp;Willd. ex Vogel.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3,4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTOTAL\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e407\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e65,8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eEighteen species were considered indicators of flooded environments according to the Indicator Species Analysis (IndVal), 9 species in the igap\u0026oacute; forest, with emphasis on the herbaceous species, \u003cem\u003eMontrichardia arborescens\u003c/em\u003e (L.) Schott. (r\u0026thinsp;=\u0026thinsp;0.98; p\u0026thinsp;=\u0026thinsp;0.001), \u003cem\u003eTrichomanes pinnatum\u003c/em\u003e Hedw. (r\u0026thinsp;=\u0026thinsp;0.84; p\u0026thinsp;=\u0026thinsp;0.001) and \u003cem\u003eBecquerelia\u003c/em\u003e sp, (r\u0026thinsp;=\u0026thinsp;0.78; p\u0026thinsp;=\u0026thinsp;0.001), while in the v\u0026aacute;rzea forests, the highlights are the palm species, \u003cem\u003eEuterpe oleracea\u003c/em\u003e Mart. (r\u0026thinsp;=\u0026thinsp;0.87; p\u0026thinsp;=\u0026thinsp;0.001) and two species with arboreal life form, \u003cem\u003eZygia ramiflora\u003c/em\u003e (Benth.) Barneby \u0026amp; J.W.Grimes (r\u0026thinsp;=\u0026thinsp;0.74; p\u0026thinsp;=\u0026thinsp;0.001) and \u003cem\u003eVirola surinamensis\u003c/em\u003e (Rol. ex Rottb.) Warb. (r\u0026thinsp;=\u0026thinsp;0.72; p\u0026thinsp;=\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSpecies Indicators of flooded environments according to the Indicator Species Analysis (IndVal) in v\u0026aacute;rzea and igap\u0026oacute; forests in the Ferreira Penna Scientific Station, Caxiuan\u0026atilde; National Forest, Par\u0026aacute;, Brazil\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eForest type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eScientific names\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFamily\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLife forms\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eMontrichardia arborescens\u003c/em\u003e. (L.) Schott.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eTrichomanes pinnatum\u003c/em\u003e Hedw.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHeminophyllaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBredemeyera Willd.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCyperaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRapatea paludo\u003c/em\u003esa Aubl.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRapataceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eCaraipa grandifolia\u003c/em\u003e Mart.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eClusiaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.043\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eErisma uncinatum\u003c/em\u003e Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVochysiaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMachaerium Pers. sp 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eOlyra\u003c/em\u003e L.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePoaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.023\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgap\u0026oacute;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRhynchospora pubera\u003c/em\u003e (Vahl) Boeckeler\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCyperaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.043\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eEuterpe oleracea\u003c/em\u003e Mart.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eArecaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eZygia ramiflora\u003c/em\u003e (Benth.) Barneby \u0026amp; J.W.Grimes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eVirola surinamensis\u003c/em\u003e (Rol. ex Rottb.) Warb.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMyristicaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePterocarpus santalinoides\u003c/em\u003e L H\u0026eacute;r. ex DC. LC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eMauritia flexuosa\u003c/em\u003e L.f.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eArecaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePalm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePhilodendron muricatum\u003c/em\u003e Willd. ex Schott.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eCynometra bauhiniifoli\u003c/em\u003ea Benth.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFabaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eMontrichardia linifera\u003c/em\u003e (Arruda) Schott\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAraceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHerb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u0026aacute;rzea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eErisma calcaratum\u003c/em\u003e (Link) Warm.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVochysiaceae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTree\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.022\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe principal component analysis (PCA) of natural regeneration revealed a clear separation between the igap\u0026oacute; and v\u0026aacute;rzea forest plots along the first axis. It explained 56.5% of the total data variation, while the second axis explained 27.6% of the variation, fundamental to understanding the internal dynamics of the v\u0026aacute;rzea (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The axes clearly show a structural gradient of regeneration, ranging from plots dominated by herbaceous plants in igap\u0026oacute; forests (negative extreme) to plots with greater recruitment of arboreal individuals, palms, and epiphytes (positive extreme) in v\u0026aacute;rzea plots (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe comparison between igap\u0026oacute; and v\u0026aacute;rzea forests at the Ferreira Penna Scientific Station revealed striking differences in the composition and abundance of species in natural regeneration. We can attribute this to a combination of edaphic, hydrological, and structural factors.\u003c/p\u003e \u003cp\u003eThe igap\u0026oacute; forest plots were predominantly associated with herbaceous plants, evidencing a limitation in the establishment of woody, but nutrient-dependent, life forms. This pattern is consistent with the more restrictive environmental conditions of this environment, characterized by acidic soils, poor in nutrients such as H\u0026thinsp;+\u0026thinsp;Al, Al, coarse sand, silt, and N% (Pinheiro and Ferreira \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), in addition to being more shaded and subject to a generally more prolonged flooding regime. These conditions may act as environmental filters, reducing the abundance and growth of tree species and favoring herbaceous species with short life cycles, adapted to oligotrophic soils and hydrological stress (Ferreira et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eStudies on plant regeneration and reproduction in floodplain forests indicate that environments subject to prolonged flooding and low fertility restrict the establishment of long-life cycle plants, such as trees, favoring herbaceous or fast-cycle forms (Ferreira et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). This environmental filtering mechanism is supported by the results of Muscarella et al. (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), who demonstrated that edaphic gradients and the flooding regime play a central role in structuring Amazonian plant communities. According to these authors, environments with greater hydrological stress and lower fertility tend to have more clustered communities, either functionally or phylogenetically, indicating that only a restricted set of ecological strategies can persist under such conditions. This pattern is consistent with the predominance of igap\u0026oacute; plots dominated by herbaceous plants, as observed in the analysis.\u003c/p\u003e \u003cp\u003eIn contrast, the v\u0026aacute;rzea plots showed a more structured regeneration, with a greater contribution from trees and palms. This reflects the greater fertility of these environments, fed by whitewater rivers rich in sediments. Factors such as pH, Mn, Fine Sand, K, Fe, Ca\u0026thinsp;+\u0026thinsp;Mg, Ca, Zn, play a crucial role in structuring the plant communities of natural regeneration in this environment (Pinheiro and Ferreira \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Under these conditions, the environmental filter is less severe, allowing the establishment and coexistence of woody life forms with different ecological strategies, resulting in greater structural complexity of regeneration.\u003c/p\u003e \u003cp\u003eIn addition, v\u0026aacute;rzea forests are subjected to intensive wind action, which causes large movements in the waters of Caxiuan\u0026atilde; Bay, resulting in mechanical damage to the plant community (Pinheiro \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This same phenomenon has already been cited for floodplain forests in western Amazonia (Haugaasen and Peres \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) and in Central Amazonia (Ferreira et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis high degree of disturbance results in a high annual mortality rate with annual rates of 1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2, year\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the Caxiuan\u0026atilde; bay, which represents double the values ​​obtained in the igap\u0026oacute; forests of the Curu\u0026aacute; River, 0.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2%, year\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Cunha \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). These mortality rates are also higher than those recorded in terra firme forests in adjacent areas, in the Caxiuan\u0026atilde; National Forest, ranging from 0.9% to 1.2% (Costa et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOne of the main consequences of this natural impact is the increased canopy opening in the v\u0026aacute;rzea forests of the study region, which facilitates the establishment of plant dispersal propagules with arboreal and palm life forms that require large amounts of light and nutrient-rich soils for establishment and growth (Ferreira et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe palm trees showed great abundance of clump-forming a\u0026ccedil;a\u0026iacute; seedlings (\u003cem\u003eEuterpe oleraceae\u003c/em\u003e Mart.) only in the natural regeneration plots of the v\u0026aacute;rzea forests of Caxiuan\u0026atilde; Bay. This is not surprising, since Ferreira et al. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) recorded 875 adult clump-forming a\u0026ccedil;a\u0026iacute; individuals, with diameters greater than 10 cm, in two permanent one-hectare vegetation plots planted in the floodplain forests of Caxiuan\u0026atilde; Bay and only 10 adult individuals in 2 one-hectare plots in the igap\u0026oacute; forests planted in the Curu\u0026aacute; River.\u003c/p\u003e \u003cp\u003eSeveral palm species are better competitors for nutrients in the fertile environments of flooded v\u0026aacute;rzea forests in the Amazon basin, as already recorded in Amazonian estuaries. They are dominant in many flooded v\u0026aacute;rzea forests in the states of Par\u0026aacute; (Jardim and Vieira \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) and Amap\u0026aacute; (Carim \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe absence of these natural impacts on the vegetation of the igap\u0026oacute; forests of the Curu\u0026aacute; River, the area of ​​this study, allows for greater shading of the understory. This enhances shade-tolerant species from the herbaceous plant community to be the life forms with the greatest abundance of individuals, such as species from the angiosperm families Cyperaceae, Rapateaceae, Maranthaceae, among others, also recorded by Maciel-Silva et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) and Pinheiro and Ferreira (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) in other interfluves of igap\u0026oacute; forests of the Ferreira Scientific Station in Caxiuan\u0026atilde;. The most abundant species in the flooded forests of the Curu\u0026aacute; River, the terrestrial fern \u003cem\u003eTrichomanes pinnatum\u003c/em\u003e Hedw (Hymenophyllaceae), is absent from the natural regeneration plots of the v\u0026aacute;rzea forests of Caxiuan\u0026atilde; Bay. Our hypothesis is that the larger canopy openings in the v\u0026aacute;rzea forests may hinder the regeneration of this species, a situation that does not occur in the flooded forests of the river. Zuquim et al. (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) report that in humid tropical forests, high humidity and shading are essential conditions for the development of ferns and lycophytes.\u003c/p\u003e \u003cp\u003ePhillips et al. (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2003\u003c/span\u003e) state that the predominant factor in floristic composition is the variation in soil types, and that edaphic correlation can explain about 90% of the variation in diversity found, while Souza et al. (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) report that the distribution of species along a topographic gradient is associated with variations in chemical fertility, acidity, and soil texture. Furthermore, igap\u0026oacute; forests with nutrient-poor soils tend to have greater species diversity because of greater competition for light, while v\u0026aacute;rzea forests, richer in nutrients and with lower diversity, are consequences of better competition among trees for nutrients that excluded other forms of life (Matos \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMatos et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) recorded \u003cem\u003eMacrolobium angustifolium\u003c/em\u003e (Benth.) R.S.Cowan as one of the common and abundant tree species among two igap\u0026oacute; and v\u0026aacute;rzea forests in the same area of this study and associated this with the species' capacity in relation to different combinations of functional attributes related to different levels of soil nutrients and light availability between the two types of flooded forests. In the v\u0026aacute;rzea forests of Caxiuan\u0026atilde; Bay, adult populations of this species have small leaves and individuals of low stature. This may suggest adaptations to take advantage of the greater canopy opening. In contrast, in the igap\u0026oacute; forests of the Curu\u0026aacute; River, the leaves are larger, with a greater leaf area, probably to maximize the capture of solar radiation that reaches the understory. This is a strategy to increase photosynthesis under conditions of more intense shade. Furthermore, Batista (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) analyzed the functional traits of \u003cem\u003eSwartzia acuminata\u003c/em\u003e Willd. ex Vogel (Fabaceae), another representative species of the region's floodplain forests. They observed that populations of this species showed significant differences in functional characteristics, such as leaf area and leaf dry matter content, between igap\u0026oacute; and v\u0026aacute;rzea forests, with higher values ​​in v\u0026aacute;rzea forests.\u003c/p\u003e \u003cp\u003eThe principal component analysis (PCA) revealed a clear separation between the two forest types along the first axis, with the second axis explaining 27.6% of the variation. This is essential to understanding the internal dynamics of v\u0026aacute;rzea forests. This axis indicates important variations in the composition of regeneration, especially related to the dominance of palms. The distinction between vegetation types suggests different successional trajectories and an influence of micro environmental conditions, such as variations in flood duration, topography, and resource availability.\u003c/p\u003e \u003cp\u003ePlots located in the upper right portion of the graph showed a greater association with the tree habit, while others were strongly associated with palms, indicating an environmental gradient in regeneration. This internal separation within the set of floodplain plots indicates that this environment does not constitute a homogeneous unit from the point of view of natural regeneration. On the contrary, the distribution of plots along the second axis reflects the environmental and structural heterogeneity of the floodplains. This highlights the high carrying capacity of these areas for woody vegetation, as suggested by Muscarella et al. (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). They demonstrated that fertility and flooding gradients promote strong differentiation in the composition and structure of plant communities in floodable Amazonian forests.\u003c/p\u003e \u003cp\u003eThe comparison between igap\u0026oacute; and v\u0026aacute;rzea forests provides new perspectives on the dynamics of ecological succession in these flooded ecosystems. This highlights how winds and environmental gradients (soil fertility, flooding regime, and light availability) shape the structure of plant communities. Our study reveals that, in igap\u0026oacute; forests, natural regeneration is predominantly herbaceous, reflecting the more restrictive conditions of poor soil and prolonged flooding, while in v\u0026aacute;rzea forests, the richer nutrient conditions favor a more structured regeneration, with a predominance of trees and palms.\u003c/p\u003e \u003cp\u003eA deeper analysis of these functional plant strategies, considering the level of competition for light and nutrients and the microenvironmental conditions, is crucial to improve the understanding of the ecological processes that govern natural regeneration and functional diversity in these flooded ecosystems of the Amazon. Future research should consider not only edaphic and hydrological aspects, but also how biological and ecological variables interact to promote ecological succession and the permanence of plant communities in these dynamic environments.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study contributes to the understanding of the ecological processes that shape the flooded forests of Eastern Amazonia. The differences observed in the natural regeneration of igap\u0026oacute; and v\u0026aacute;rzea forests, in terms of life forms and community structure, reveal the importance of edaphic and hydrological conditions in the formation of these plant communities. Igap\u0026oacute; forests, with low-fertility soils and prolonged flooding regimes, were dominated by herbaceous species. V\u0026aacute;rzea forests, with higher fertility and a more dynamic hydrological regime, favored the establishment of trees and palms.\u003c/p\u003e \u003cp\u003ePrincipal component analysis (PCA) was crucial to identify these differences and to understand how factors such as light and nutrient availability influence the structure of natural regeneration. By highlighting these variations, the study emphasizes the ecological complexity of flooded forests and the need to consider environmental heterogeneity in the management and conservation of these ecosystems.\u003c/p\u003e \u003cp\u003eThe ecological importance of understanding these processes is clear: floodplain forests play crucial roles in regulating water cycles, controlling soil erosion, and maintaining local biodiversity. These forests are important habitats for diverse plant and animal species, many of which are adapted to the specific conditions of each vegetation type. The preservation and effective management of these areas depend on a deep understanding of the environmental factors that determine the regeneration of plant communities, as well as the functional strategies that these species use to persist in environments with strong hydrological variation.\u003c/p\u003e \u003cp\u003eFinally, the study proposes that the conservation and sustainable management of igap\u0026oacute; and v\u0026aacute;rzea forests should be based on ecological diversity and the specific conditions of each environment. It is important to take the importance of these forests into account for maintaining ecological services and biodiversity in the whole Amazon region.\u003c/p\u003e"},{"header":"Statements \u0026 Declarations","content":"\u003cp\u003e\u003cem\u003eAcknowledgments\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Long-Term Research Program (PELD)/National Council for Scientific and Technological Development (CNPq), Process: 445593/2024-5 and for a Research Productivity Grant to the last author (Process 305469/2025-8).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThis work was supported by\u0026nbsp;\u003c/em\u003eLong-Term Research Program (PELD)/National Council for Scientific and Technological Development (CNPq), Grant: 445593/2024-5 and for a Research Productivity Grant to the last author (Process 305469/2025-8).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting Interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there are no conflicts of interest regarding the research, authorship, and/or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAuthor Contributions\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eConceptualisation was done by Maiara Cunha Soares; Field data collection was done by Leandro Valle Ferreira and\u0026nbsp;Maiara Cunha Soares,\u0026nbsp;and Methodology was designed by Leandro Ferreira and Priscila Sanjuan de Medeiros Sarmento. The first draft of the manuscript was written by Leandro Valle Ferreira and\u0026nbsp;Maiara Cunha Soares. Previous versions of the manuscript were commented and Pia Parolin, Darley Calderaro Leal Matos, Marcilene da Silva Pinheiro and M\u0026aacute;rio Augusto Gon\u0026ccedil;alves Jardim. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eData Availability\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAlbernaz ALKM (2008) Conserva\u0026ccedil;\u0026atilde;o da v\u0026aacute;rzea: Identifica\u0026ccedil;\u0026atilde;o e caracteriza\u0026ccedil;\u0026atilde;o de regi\u0026otilde;es biogeogr\u0026aacute;ficas \u0026ndash; IBAMA/ProVarzea, Manaus\u003c/li\u003e\n \u003cli\u003eAngiosperm Phylogeny Group (2016) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society v.181, pp 1- 20\u003c/li\u003e\n \u003cli\u003eAtaide WLD, Oliveira FA, Braga CO, Amorim MB, Carneiro FS, Chagas GFB, Balma FB, Maestri MP (2022) Caracterizaci\u0026oacute;n de los vientos sobre Flona Caxiuan\u0026atilde; en el a\u0026ntilde;o de ENOS. Research, Society and Development 11:1-12. https://doi.org/10.33448/rsd-v11i1.22584\u003c/li\u003e\n \u003cli\u003eBatista AWS (2017)\u0026nbsp;Estudos ecol\u0026oacute;gicos de \u003cem\u003eSwartzia polyphylla\u003c/em\u003e DC. (Fabaceae) em florestas inund\u0026aacute;veis na Amaz\u0026ocirc;nia Oriental.Disserta\u0026ccedil;\u0026atilde;o, Programa de P\u0026oacute;s-Gradua\u0026ccedil;\u0026atilde;o em Bot\u0026acirc;nica Tropical (UFRA/MPEG)\u003c/li\u003e\n \u003cli\u003eCarim MJV (2016) Estrutura, composi\u0026ccedil;\u0026atilde;o e diversidade em florestas alag\u0026aacute;veis de v\u0026aacute;rzea de mar\u0026eacute; e de igap\u0026oacute; e suas rela\u0026ccedil;\u0026otilde;es com vari\u0026aacute;veis ed\u0026aacute;ficas e o per\u0026iacute;odo de inunda\u0026ccedil;\u0026atilde;o no Amap\u0026aacute;, Amaz\u0026ocirc;nia Oriental, Brasil. Tese, Instituto Nacional de Pesquisas da Amaz\u0026ocirc;nia, Manaus\u003c/li\u003e\n \u003cli\u003eCosta ACL, Galbraith D, Almeida S, Portela BTT, Costa M, Junior JAS, Braga AP, Gon\u0026ccedil;alves PHL, Oliveira AAR, Fisher R, Phillips OL, Metcalfe DB, Levy P, Meir P (2010) Effect of 7 yr of experimental drought on vegetation dynamics and biomass storage of an eastern Amazonian rain forest. New Phytologist 187:579\u0026ndash;591. https://doi.org/10.1111/j.1469-8137.2010.03309.x\u003c/li\u003e\n \u003cli\u003eCunha DA (2018) Din\u0026acirc;mica e produtividade em florestas de igap\u0026oacute; e v\u0026aacute;rzea na Amaz\u0026ocirc;nia Oriental.Tese, Programa de P\u0026oacute;s-gradua\u0026ccedil;\u0026atilde;o em Biodiversidade e Biotecnologia da Rede Bionorte\u003c/li\u003e\n \u003cli\u003eDol\u0026eacute;dec S, Chessel D (1994) Co-inertia analysis: aa alternative method for studying species: environment relationships. Freshwater Biology 31:277-294.\u0026nbsp;https://doi.org/10.1111/j.1365-2427.1994.tb01741.s\u003c/li\u003e\n \u003cli\u003eDufr\u0026ecirc;ne M, Legendre P (1997) Species assemblages and indicator species: the need for flexible asymmetrical approach. Ecological Monographs 67(3):345-366\u003c/li\u003e\n \u003cli\u003eFerreira LV (1997) Effects of flooding duration of species richness and floristic composition in three hectares in the Ja\u0026uacute; National Park in floodplain forests in central Amazonia. Biodiversity and Conservation 6:1353-1363\u003c/li\u003e\n \u003cli\u003eFerreira LV, Almeida SS, Parolin P (2010) Amazonian white- and blackwater floodplain forests in Brazil: large differences on a small scale. Ecotropica 16:31-41\u003c/li\u003e\n \u003cli\u003eFerreira, LV,\u0026nbsp;Cunha DA, Chaves, PP, Matos, DCL, Parolin P (2013) Varia\u0026ccedil;\u0026atilde;o da riqueza e composi\u0026ccedil;\u0026atilde;o de esp\u0026eacute;cies da comunidade de plantas entre as florestas de igap\u0026oacute;s e v\u0026aacute;rzeas da Esta\u0026ccedil;\u0026atilde;o Cient\u0026iacute;fica Ferreira Penna-Caxiuan\u0026atilde; na Amaz\u0026ocirc;nia Oriental. Pesquisas. Bot\u0026acirc;nica 64:175-195\u003c/li\u003e\n \u003cli\u003eFerreira LV, Maia APM, Pinheiro MS, Oliveira MC, Junior LEP, Amorim JTA, Baia LLF, Matos JHT, Jardim MAG (2023) Diversidade flor\u0026iacute;stica em fitofisionomias de duas unidades de conserva\u0026ccedil;\u0026atilde;o na Amaz\u0026ocirc;nia Oriental, Par\u0026aacute;, brasil. Revista Brasileira de Geografia F\u0026iacute;sica 16:3283-3297. https://doi.org/10.26848/rbgf.v16.6.p3283-3297\u003c/li\u003e\n \u003cli\u003eFerreira CS, Piedade MTF, Wittmann AO, Franco AC (2010) Plant reproduction in the Central Amazonian floodplains: challenges and adaptations. AoB plants 2010:plq009. https://doi.org/10.1093/aobpla/plq009\u003c/li\u003e\n \u003cli\u003eFerreira LV, Stohlgren TJ (1999) Effects of river level fluctuation on plant species richness, diversity, and distribution in a floodplain forest in central Amazonia. Oecologia 120:582-587. https://doi.org/10.1007/s004420050893\u003c/li\u003e\n \u003cli\u003eFlora e Funga do Brasil.\u0026nbsp;Jardim Bot\u0026acirc;nico do Rio de Janeiro. http://floradobrasil.jbrj.gov.br/. Acessado em 21 de janeiro de 2026\u003c/li\u003e\n \u003cli\u003eHammer \u0026Oslash;, Harper DAT, Ryan PD (2001)\u0026nbsp;PAST: Paleontological Statistics Software Package for Education and Data Analysis.\u0026nbsp;Palaeontologia Electronica4:9. https://palaeo-electronica.org/2001_1/past/issue1_01.htm\u003c/li\u003e\n \u003cli\u003eHaugaasen T, Peres CA (2006) Floristic, edaphic and structural characteristics of flooded and unflooded forests in the lower Rio Pur\u0026uacute;s region of central Amazonia, Brazil. Acta Amaz\u0026ocirc;nica 36:25-36\u003c/li\u003e\n \u003cli\u003eJardim MAG, Vieira ICG (2001) Composi\u0026ccedil;\u0026atilde;o flor\u0026iacute;stica e estrutura de uma floresta de v\u0026aacute;rzea do estu\u0026aacute;rio amaz\u0026ocirc;nico, ilha do Combu, Estado do Par\u0026aacute;, Brasil.\u0026nbsp;Boletim do Museu Paraense Emilio Goeldi - S\u0026eacute;rie Bot\u0026acirc;nica 17:333-354\u003c/li\u003e\n \u003cli\u003eJunk WJ (1997) General aspects of floodplain ecology with special reference to Amazonian floodplains. In: Junk WJ (ed). The Central Amazon Floodplain. Springer-Verlag, Berlin Heidelberg, pp 3-20\u003c/li\u003e\n \u003cli\u003eMaciel-Silva JF, Nunes CS, Ferreira LV, Bragan\u0026ccedil;a Gil AS (2019) Cyperaceae aqu\u0026aacute;ticas e palustres na Floresta Nacional de Caxiuan\u0026atilde;, Par\u0026aacute;, Amaz\u0026ocirc;nia, Brasil. Boletim do Museu Paraense Em\u0026iacute;lio Goeldi - Ci\u0026ecirc;ncias Naturais 14:391-424\u003c/li\u003e\n \u003cli\u003eMatos DCL (2018) Diversidade funcional da comunidade de \u0026aacute;rvores em florestas inundadas na Amaz\u0026ocirc;nia Oriental.Tese, Programa de P\u0026oacute;s-gradua\u0026ccedil;\u0026atilde;o em Biodiversidade e Biotecnologia da Rede Bionorte\u003c/li\u003e\n \u003cli\u003eMatos DCL, Ferreira LV, Carlucci MB (2018) Estrat\u0026eacute;gias funcionais de \u003cem\u003eMacrolobium angustifolium\u003c/em\u003e (Benth.) R.S.Cowan para coexistir em florestas inundadas na Amaz\u0026ocirc;nia oriental. Revista Spacios 39:1-16\u003c/li\u003e\n \u003cli\u003eMuscarella R, Bacon CD, Faurby S, Antonelli A, Kristiansen SM, Svenning JC, Balslev H (2019) Soil fertility and flood regime are correlated with phylogenetic structure of Amazonian palm communities. Annals of Botany 123:641-655. https://doi.org/10.1093/aob/mcy196\u003c/li\u003e\n \u003cli\u003eOksanen, J et al Vegan (2020) Community Ecology Package. R package version\u003c/li\u003e\n \u003cli\u003ePhillips OL, Vargas PN, Monteagudo AL, Cruz AP, Zans MEC, S\u0026aacute;nchez WG, Yli-Halla M, Rose S (2003) Habitat association among Amazonian tree species: a landscape scale approach. Journal of Ecology 91:757-775. https://doi.org/10.1046/j.1365-2745.2003.00815.x\u003c/li\u003e\n \u003cli\u003ePinheiro NA (2014) Balan\u0026ccedil;o de energia e fluxos turbulentos associados \u0026agrave; fatores f\u0026iacute;sicoqu\u0026iacute;micos da \u0026aacute;gua na ba\u0026iacute;a de Caxiuan\u0026atilde;. Disserta\u0026ccedil;\u0026atilde;o, Programa de P\u0026oacute;s-Gradua\u0026ccedil;\u0026atilde;o em Ci\u0026ecirc;ncias Ambientais - Universidade Federal do Par\u0026aacute;, EMBRAPA Amaz\u0026ocirc;nia Oriental, Museu Paraense Emilio Goeldi\u003c/li\u003e\n \u003cli\u003ePinheiro MS, Ferreira LV (2022) Flor\u0026iacute;stica e estrutura de florestas inundadas na Floresta Nacional de Caxiuan\u0026atilde;, Par\u0026aacute;, Brasil. Nature and Conservation 15:1-16. https://doi.org/10.6008/CBPC2318-2881.2022.003.0001\u003c/li\u003e\n \u003cli\u003eR Core Team (2021) A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/\u003c/li\u003e\n \u003cli\u003eSouza PB, Lelis JJ, Schaefer CEGR, Souza AL, Meira Neto JAA (2012) Distribution of tree species in a geomorphological and pedological gradient of submontane semidecidual seasonal forest in the vicinity of Rio Doce State Park, Minas Gerais. Revista \u0026Aacute;rvore 36:707-718. https://doi.org/10.1590/S0100-67622012000400012\u003c/li\u003e\n \u003cli\u003eVeloso HP, Rangel Filho ALR, Lima JCA (1991) Classifica\u0026ccedil;\u0026atilde;o da Vegeta\u0026ccedil;\u0026atilde;o Brasileira, adaptada a um sistema universal.\u0026nbsp;IBGE, Rio de Janeiro\u003c/li\u003e\n \u003cli\u003eWittmann F, Junk WJ, Schongart J (2010) Phytogeography, species diversity, community structure and dynamics of central Amazonian floodplain forests. In: Junk WJ et al. (Eds), Central Amazonian Floodplain Forests: Ecophysiology, Biodiversity and Sustainable Management, Ecological Studies, Springer Verlag, pp 61-102. https://doi.org/10.1007/978-90-481-8725-6_4\u003c/li\u003e\n \u003cli\u003eWorbes M (1997) The forest ecosystem of the floodplains. In: The Central Amazon floodplain: Ecology of a pulsing system. Berlin, Heidelberg: Springer Berlin Heidelberg 126:223-265\u003c/li\u003e\n \u003cli\u003eZuquim G, Costa FRC, Prado J (2007) Fatores que determinam a distribui\u0026ccedil;\u0026atilde;o de esp\u0026eacute;cies de pterid\u0026oacute;fitas da Amaz\u0026ocirc;nia Central. Revista Brasileira de Bioci\u0026ecirc;ncias 5:360-362. https://seer.ufrgs.br/index.php/rbrasbioci/article/view/115114\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Amazonian, flood forests, igapó, natural regeneration, várzea","lastPublishedDoi":"10.21203/rs.3.rs-9368458/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9368458/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn the Amazon, floodplain vegetation comprises extensive ecosystems whose ecological dynamics tied to the seasonal fluctuations in river levels. These transitional environments, known as igap\u0026oacute; and v\u0026aacute;rzea, serve as interfaces between aquatic and terrestrial systems, exhibiting distinct variations in species diversity, structural composition, and ecological functions. Igap\u0026oacute; vegetation dominates regions with low soil fertility, occurring along blackwater and clearwater rivers, whereas v\u0026aacute;rzea vegetation is found in areas influenced by whitewater rivers, rich in sediments and nutrients. The objective of this study was to compare the abundance of life forms involved in natural regeneration across igap\u0026oacute; and v\u0026aacute;rzea forests. The research was conducted at the Caxiuan\u0026atilde; National Forest, Brazil. Six distinct life forms were identified within these flooded forests, with trees (37.8%), palms (35.6%), and herbaceous plants (14%) being the most prominent. A pronounced distinction in natural regeneration patterns was observed between the two forest types: igap\u0026oacute; plots were predominantly dominated by herbaceous plants, while v\u0026aacute;rzea plots displayed greater recruitment of arboreal species, palms, and epiphytes. This gradient of regeneration reflects not only the soil and water conditions of each forest type but also their role in maintaining distinct ecological processes. Understanding the dynamics of natural regeneration in floodplain forests is vital, given their essential role in regulating hydrological cycles, preventing soil erosion, and supporting biodiversity. The distribution of species in both igap\u0026oacute; and v\u0026aacute;rzea forests highlight their critical role in sustaining these dynamic ecosystems, which are indispensable for a variety of plant and animal species.\u003c/p\u003e","manuscriptTitle":"Hydrological and edaphic filters structure early plant community assembly in Amazonian floodplain forests","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-18 06:45:20","doi":"10.21203/rs.3.rs-9368458/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-05-08T12:48:23+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-07T13:15:28+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Wetlands","date":"2026-05-06T15:28:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-06T08:23:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Wetlands","date":"2026-05-05T10:06:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"80a3be45-f05e-4e5b-98b1-492eb216b5b6","owner":[],"postedDate":"May 18th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"","date":"2026-05-08T12:48:23+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-07T13:15:28+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Wetlands","date":"2026-05-06T15:28:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-06T08:23:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Wetlands","date":"2026-05-05T10:06:52+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T06:45:20+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-18 06:45:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9368458","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9368458","identity":"rs-9368458","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}