Complex plasticity in biomass allocation in response to light availability and plant-plant interactions

Complex plasticity in biomass allocation in response to light availability and plant-plant interactions | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 18 February 2025 V1 Latest version Share on Complex plasticity in biomass allocation in response to light availability and plant-plant interactions Authors : Qingzhu Yang 0009-0000-3413-8284 , Shu Wang 0000-0002-5353-6744 [email protected] , Jia Chen , Renya Yin , Linli Chen , and xia Hou 0009-0003-6471-1573 Authors Info & Affiliations https://doi.org/10.22541/au.173990535.59353793/v1 294 views 128 downloads Contents Abstract Study species Experimental design Data collection and statistical analyses Effects of neighbors on response to light conditions Effects of light conditions on response to neighbors Effects of neighbors on plant response to shading Comparison on the two species Effects of light conditions on response to neighbors Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract 1. Plants are often exposed to multiple abiotic and biotic environmental variations in nature, but studies are very scarce on how plant respond to biotic variations, or interactive effects of abiotic and biotic factors. 2. Our objective was to investigate effects of light conditions on responses of plant biomass allocation to conspecific or heterospecific neighbors, and effects of these neighbors on plant response to shading vs. full light conditions. 3. We subjected plants of Buddleja lindleyana and Bidens pilosa to three treatments of solitary growth (control), intra- and interspecific interaction, under 50% shading and full light conditions, and measured a series of biomass and morphological traits on them. 4. Full light relative to shading decreased total mass, root mass and root:shoot ratio of B. pilosa under intraspecific competition, but increased them for both species grown alone and with heterospecific neighbors. Compared to those grown alone, intraspecific interaction increased mean total mass for B. lindleyana and increased root mass and root: shoot ratio for both species in shading, but reduced total mass and root:shoot ratio of B. pilosa under full light, with no effects of interspecific interaction. 5. Results suggested conspecific neighbors will more likely interfere with plant acquiring resources, making it more difficult or less efficient for plants to utilize the resources. Plants will adjust the strategy of biomass allocation for maximizing growth depending on both resource availability and accessibility, to enhance the efficiency of resource acquiring under severe environmental challenges. 6. Synthesis. By investigating responses of plants to variations in abiotic conditions and plant interactions simultaneously, we not only provided direct evidence for responses of plants to complex environmental factors, but also revised the optimal partitioning theory by emphasizing the importance of resource accessibility. Complex plasticity in biomass allocation in response to light availability and plant-plant interactions Qing-Zhu Yang Shu Wang* Jia-Xing Chen Ren-Ya Yin Lin-Li Chen Xia-Li Hou College of Forestry and Forest Ecology Research Center, Guizhou University, Guiyang, 550025, China *Corresponding Author. Email: [email protected] College of Forestry, Guizhou University, Guiyang, 550025, China. Tel: 0851-88298015; Fax: 0851-83851335; Running title: Plasticity response to light and neighbors Acknowledgements We are grateful for the reviewers and editors who all provided useful feedback on this manuscript. Summary 1. Plants are often exposed to multiple abiotic and biotic environmental variations in nature, but studies are very scarce on how plant respond to biotic variations, or interactive effects of abiotic and biotic factors. 2. Our objective was to investigate effects of light conditions on responses of plant biomass allocation to conspecific or heterospecific neighbors, and effects of these neighbors on plant response to shading vs. full light conditions. 3. We subjected plants of Buddleja lindleyana and Bidens pilosa to three treatments of solitary growth (control), intra- and interspecific interaction, under 50% shading and full light conditions, and measured a series of biomass and morphological traits on them. 4. Full light relative to shading decreased total mass, root mass and root:shoot ratio of B. pilosa under intraspecific competition , but increased them for both species grown alone and with heterospecific neighbors. Compared to those grown alone, intraspecific interaction increased mean total mass for B. lindleyana and increased root mass and root: shoot ratio for both species in shading, but reduced total mass and root:shoot ratio of B. pilosa under full light, with no effects of interspecific interaction. 5. Results suggested conspecific neighbors will more likely interfere with plant acquiring resources, making it more difficult or less efficient for plants to utilize the resources. Plants will adjust the strategy of biomass allocation for maximizing growth depending on both resource availability and accessibility, to enhance the efficiency of resource acquiring under severe environmental challenges. 6. Synthesis . By investigating responses of plants to variations in abiotic conditions and plant interactions simultaneously, we not only provided direct evidence for responses of plants to complex environmental factors, but also revised the optimal partitioning theory by emphasizing the importance of resource accessibility. Key-words: biomass allocation; interspecific interaction; intraspecific interaction; neighbor; optimal partitioning theory; phenotypic plasticity; resource availability; root:shoot ratio; shading INTRODUCTION Plants are able to deal with environmental variations through phenotypic plasticity, defined as the ability of an organism to alter its phenotype in response to environmental changes (Bradshaw 1965; Scheiner 1993; Pfennig 2016). Plasticity in biomass allocation reflects plant strategies of survival and persistence, and thus often be of greater ecological importance than physiological mechanisms at cellular or molecular levels (Schwinning and Weiner 1998). Generally, the optimal partitioning theory (OPT) predicts that plants will allocate greater biomass to the organs that acquire the most limiting resources in order to maximize growth rates (Bloom et al. 1985; Gedroc et al. 1996; McCarthy and Enquist 2007). For instance, plants will increase leaf mass allocation to acquire more light and CO 2 under shade conditions (Quero et al. 2006), but will allocate more biomass to roots when belowground resources are deficient (Vogel et al. 2008; Freschet et al. 2015; Wang et al. 2021b). In natural conditions, however, plants may be frequently exposed to variations in multiple abiotic and biotic factors simultaneously. However, the OPT cannot predict the strategy of plants in dealing with environmental changes in such complexity. It involves effects of biotic factors on plant response to abiotic conditions, as well as effects of abiotic conditions on plant response to biotic variations, which all have been rarely studied (but see Wang and Callaway 2021). For example, plants interacting with a conspecific neighbor will have stronger decrease in root:shoot ratio in response to drought conditions than those grown alone (Wang and Callaway 2021). It is well documented that shading or lower R:FR ratio can induce extra elongation of stems and increased stem allocation in plants (Schmitt et al. 1995; Franklin and Whitelam 2005; Jeong et al. 2024), but we know little about whether and how such response to shading can be altered by the presence of neighbors. Competition may decrease the light availability for plants, thus will it stimulate stronger responses in biomass allocation of plants, or reduce their ability to adjust allocation pattern? And will effects of conspecific and heterospecific neighbors differ on plant response to shading? The first aim of this study was to investigate effects of neighbors on plant response to shading versus full light conditions. The presence of neighbor plants often result in changes in availability of multiple resources (Casper et al. 1998), inducing complex responses in plants (Wang et al. 2017; Wang and Zhou 2021). Due to such complexity of biotic effects, the OPT also cannot predict whether and how plant response to neighbors, neither can predict effects of abiotic conditions on such response. Abiotic conditions can alter plant response to competition through effects on plant size or competition intensity (Wang et al. 2017; Wang and Zhou 2021). For example, deficiency in belowground resources may intensify intraspecific competition, leading to aggravated decrease in root: shoot ratio for plants in crowded population (Wang and Callaway 2021; Wang et al. 2021b). It is reported effects of water conditions on plant response to the presence of heterospecific neighbors may differ, depending on specific species (Weigelt et al. 2005; Wang and Callaway 2021). Relevant studies have been very scarce. We do not know how aboveground resources such as light availability will affect plant response to neighbors, nor whether its effects differ for plant response to intra- and interspecific interactions. Karst ecosystem is the geomorphological feature formed by the dissolution of carbonate rocks (Legrand 1973), characterized by greater heterogeneity of environmental factors than other ecosystems (Sheng et al. 2018). In karst habitats, the availability of light, water, and nutrient resources have been key factors limiting plant growth (Guo et al. 2017; Geekiyanage et al. 2019; Liu et al. 2021; Wang et al. 2021a). Meanwhile, restricted living space due to exposed rocky surfaces and discontinuous soil cover (Zhang et al. 2014; Zhang et al. 2016; Jiao et al. 2024) may allow plants to more frequently experience interactions with neighboring plants of the same or different species (Chen et al. 2024). Therefore, plants adaptive to karst habitats may have stronger ability to deal with to complex environment changes through plasticity, compared to other plant species (Wang et al. 2023). Although there have been a great amount of studies on responses of karst plant species to abiotic factors such as light, water, and minerals, etc (Swaffer et al. 2014; Chen et al. 2015; Nardini et al. 2016; Wei et al. 2018; Bai et al. 2019; Zhang et al. 2019), we know very little about how they deal with the complex effects of plant-plant interactions, and abiotic conditions (but see Chen et al. 2023). To better understand the strategy of plants in coping with complex environmental variations, we conducted a greenhouse experiment, using two common plant species that are adaptive to karst habitats, Buddleja lindleyana Fortune and Bidens pilosa L . , to answer the following questions: 1) will the presence of neighbors alter responses of biomass allocation to shading? 2) will shading alter responses of plant biomass allocation to neighbors? 3) do the above effects differ for intraspecific and interspecific interactions, and/or for the two species? MATERIALS AND METHODS Study species We used two species of Buddleja lindleyana Fortune (Scrophulariaceae) and Bidens pilosa L . (Asteraceae), which are native and invasive species to karst regions of Guizhou respectively. Both species widely distributed across China, with the greatest abundance in southwestern China, with considerable morphological and allocation plasticity in response to light, water, and nutrient conditions (Jiaxing et al. 2023; Chen et al. 2024). B. lindleyana thrives in warm and humid climates and prefers deep, fertile soil conditions. B. pilosa is noted for its strong adaptability and competitive ability. They often co-occur in shrublands along ditches and on wastelands, with significantly overlapped distribution range. Experimental design The experiment was conducted in a greenhouse on the West Campus of Guizhou University in Guiyang Guizhou Province, China (26°27′13″N，106°40′19″E), altitude of 1020 m. The region has a typical subtropical monsoon climate, with annual average temperature of 15.3 °C, relative humidity of 77%, total precipitation of 1129.5 mm, and insolation duration of 1148.3 h. Seeds were collected from wild natural populations along the shoreside of Nan-Ming River near Huaxi Reservoir in Guiyang between June and August in 2020. After collection, the seeds were washed and air-dried indoors, before they were rinsed with distilled water and disinfected with a 0.4% potassium permanganate solution for 30 minutes and then stored at 5°C in early January. In June 2021, seeds were grown and cultivated in trays in an artificial climate chamber in the laboratory of the College of Forestry of the university. Two weeks later, seedlings with uniform growth were transplanted into pots (20 cm in diameter and 17 cm in height) filled with a sterile mixture of vermiculite, quartz sand, and perlite in a volume ratio of 3:1:1. After another two-week period for acclimation, each pot was uniformly applied with a base fertilizer with nutrient levels of 1.03 g/kg for nitrogen, 0.099 g/kg for total phosphorus, and 3.86 g/kg for total potassium. The length of the largest leaf was measured for each individual plant as the initial size (IS), before they were subjected to light treatments. The experiment used a split-plot design, which included two light treatments and three interaction strategies. The light treatment was considered the main factor, including full light (FL) and moderate shading (MS). Under each light condition, plants were exposed to three species interaction strategies of no interaction (NI), intraspecific (INTRA) and interspecific interaction (INTER). Each combination of light treatment and species strategy for each species was replicated ten times, resulting in a total sample size of: [10 (control) + 10 × 2 (intraspecific) + 10 (interspecific)] × 2 light treatments × 2 species = 160 samples. The treatment of moderate shading (MS) was manipulated by covering the experimental region with a layer of black nylon mesh shading net with approximately 50% light transmittance, with no use of shading net in full-light treatment (FL). For each light treatment, seedlings with the three interaction strategies were randomly arranged within each light treatment. Plants were watered to saturation every day. Pots were interchanged positions every three days, to ensure that all pots received consistency of light conditions. For all interaction treatments, two individuals were grown per pot, with an interspace of less than 2 cm. The pots in no interaction were segregated with a colorless transparent plastic divider (40 cm long and 20 cm wide) into two halves, with one individual plant in each half, to avoid any interaction and ensure they occupy the same space and resource compared to those in interaction treatments. The individuals of intraspecific and interspecific interaction treatments were not separated to allow sufficient root contact and interaction with the neighbor of the same or different species. Data collection and statistical analyses All treatments lasted for 40 days, before all the plants were harvested and measured for morphological traits, including plant height (from the base to the apex), basal diameter, number of leaves, and total leaf area. Then they were separated into root, stem, leaf and petiole parts and put into envelopes, oven dried at 75°C for approximately 48 h to constant and weighed. Total biomass, shoot biomass, root: shoot ratio and specific leaf area were calculated. All data analyzed with SPSS 26.0 software, and graphs were created using Origin 2018. All data was transformed to logarithmic form to reduce heterogeneity of variance. Effects of species, light treatment, and interaction strategy on all characteristics were analyzed using a three-way ANCOVA, with initial size as the covariate for total biomass and total biomass as the covariate for all the other traits. For all traits of each species, separate one-way ANCOVAs were used for effects of light or interaction treatment within each of the other treatments, with initial size as the covariate for total biomass and total biomass as the covariate for all the other traits. Multiple comparisons were performed using the Least Significant Difference method (LSD) in the general linear model (GLM), which produced adjusted mean values (used to calculate trait plasticity). The plasticity for a given trait is calculated using the modified and simplified Relative Distance Plasticity Index (RDPIs, simplified to PI) (Navas and Garnier 2002; Weijschedé et al. 2006; Wang and Callaway 2021), with the formula as follows: \begin{equation} \begin{matrix}PI=\frac{X–Y}{Y}\\ \end{matrix}\nonumber \\ \end{equation} where X and Y represented mean trait values (original or adjusted) for each species in the treatment inducing the plastic response (shading or interaction) and the control treatment (full light or no interaction) respectively. PI values were regarded as significant when mean values of the two treatments differed significantly at the 0.05 level (LSD method in one-way ANOVA or ANCOVA). RESULTS After removing the effects of the covariate, there were still very significant differences between the two species in total mass, plant height, and specific leaf area. Light conditions and interaction strategy had significant effects on most traits, and the interaction between light conditions and interaction strategy had significant effects on most traits (Table 1). Effects of neighbors on response to light conditions Plant response to shading versus light conditions was more significant for Bidens pilosa than for Buddleja lindleyana . For B. pilosa grown alone, shading relative to full light reduced its total mass by 43.9% (ANCOVA, LSD, P= 0.001), producing negative plasticity with PI of -0.48; but increased its total mass by 70.3% ( P =0.006; PI 0.68) when interacting with an intraspecific neighbor (Figures 1 and 2). No response to shade was found for B. lindleyana . Under interspecific interaction, shading relative to full light reduced the total mass of both B. lindleyana and B. pilosa by 34.1% and 43.9% respectively ( P < 0.05; PI -0.49 and -0.61). The plastic responses of the two species to shading under different plant interactions are distinct (Figure 2, Figures S1b and S2b). Across all interaction treatments, shading increased specific leaf area for both species (ANCOVA, LSD, P <0.05; PI 0.20 to 2.04). When grown alone and with an interspecific neighbor, shading increased leaf mass and above-ground mass for B. pilosa ( P < 0.05; PI 0.15 to 0.34), decreased root mass and root:shoot ratio ( P < 0.05; PI -0.21 to -0.51) for both species. Under intraspecific interaction, shading increased petiole mass, root mass and root: shoot ratio ( P<0.05 ; PI 0.21 to 0.36), but decreased above-ground mass ( P< 0.001; PI -0.07) for B. pilosa , and also reduced the petiole mass of B. lindleyana ( P= 0.012). Effects of light conditions on response to neighbors Effects of light conditions on plant response to conspecific neighbors differed significantly for the two species (Figures 1 and 3). In shade conditions, compared to those grown alone (no interaction), intraspecific interaction increased mean total mass of Buddleja lindleyana by 52.3% (ANCOVA, LSD, P= 0.046), showing positive plasticity (PI 0.36) in the trait, but did not affect that of Bidens pilosa. By contrast, under full light, compared to control, intraspecific interaction reduced mean total mass of B. pilosa by 67.1% ( P< 0.001; PI -0.66), with no effects for B. lindleyana . Under both kinds of light conditions, effects of interspecific interaction were not significant for either species. For the other traits, effects of light conditions were also significant for plant response to intraspecific interaction, and effects also differed for the two species (Figure 3, Figures S1c and S2c). In shade, intraspecific interaction increased root mass and root: shoot ratio (ANCOVA, LSD, P< 0.001; PI 0.33-0.57), but reduced leaf mass and above-ground mass ( P< 0.01; PI -0.13 to -0.05) for both species. Under full light, intraspecific interaction increased above-ground mass ( P= 0.031; PI 0.14), decreased root mass and root: shoot ratio ( P < 0.05; PI -0.44 to -0.24) for B. pilosa , but not for B. lindleyana . Effects of interspecific interaction were not significant for either species under both light conditions. DISCUSSION Effects of neighbors on plant response to shading The optimal partitioning theory (OPT) posits that plants will allocate more biomass to the organs that acquire the most limiting resource, thereby maximizing growth (Thornley 1972; Bloom et al. 1985; Müller et al. 2000; Wang and Zhou 2021). However, it cannot predict how plants allocate biomass to different organs when they face more complex situations such as the simultaneous presence of shading and competitors (Wang and Zhou 2021). Our results showed that for plants grown alone, they generally increased shoot mass and decreased root mass and root:shoot ratio in response to shade (Poorter and Nagel 2000), according with the prediction of optimal partitioning theory (Poorter and Nagel 2000; Ledo et al. 2018; Reich et al. 2014). When grown with conspecific competitors, however, this trend weakened and even became the contrary pattern. Combining the results of plant response to conspecific neighbors in contrasting light conditions with that in contrasting water or nutrient conditions (Sauter et al. 2021; Wang and Callaway 2021; Chen et al. 2024), we were able to find that interaction with neighbors will alter how a plant responds to the deficiency of resources via plasticity in biomass allocation, which is predicted in OPT. Neighbors or competitors interfere with the process of plant foraging resources, making the resources more difficult to acquire or making the efforts of plants less efficient or even futile (Cahill et al. 2010; Wang and Callaway 2021). When competitors are absent, plants are definitely able to acquire resources through increasing investment into the corresponding organs. In the presence of competitors, it becomes unpredictable whether they can obtain the resources in need by enhanced energy investment, due to the disturbance of competitors. Consequently, they will more likely alter the strategy of acquiring resources, for example, to invest more energy into growth in another direction. Therefore, the strategy of plant biomass allocation for maximizing growth depends on two aspects of factors: resource availability and whether the resource is accessible. Such strategy should enable plants to increase the efficiency of resource utilization in face of severe environmental challenge. Comparison on the two species Our results showed that when grown alone or interacting with a heterospecific neighbor, full light relative to shading conditions increased total biomass and root: shoot ratio, but decreased its total biomass and root: shoot ratio for Bidens pilosa when interacting with a neighbor of the same species. The presence of conspecific neighbors can intensify competition for resources among plants (Wright et al. 2014). It can lead to stronger decrease in root:shoot ratio in response to drought versus mesic conditions, which is facilitative to plants (Wang and Callaway 2021). In comparison, the decrease of root:shoot ratio in response to full light versus shading which was not facilitative for B. pilosa interacting with conspecific neighbors, suggesting intraspecific competition was stronger for B. pilosa in full light relative to shading conditions, and the intensified aboveground competition does not allow for an efficient increase in shoot mass to enhance the acquirement of light resource. This should mainly be because for B. pilosa , aboveground growth prevailed over belowground growth, leading to stronger aboveground competition (Chen et al. 2024); while the extensive growth of aboveground biomass further intensified aboveground competition under full light, impeding whole-plant growth. Therefore, increasing investment to aboveground vs. belowground growth in response to full light versus shading was not an advantageous strategy for B. pilosa . By contrast, intraspecific interaction did not result in significant changes in total mass or root:shoot ratio; whereas interacting with Buddleja lindleyana led to aggravated decrease in total mass and root:shoot ratio by shading versus full light, compared to those grown alone with no response in total mass and decreased root:shoot ratio by shading. It suggested conspecific neighbors had more beneficial effects than B. pilosa. Chen et al. (2024) reported that both intra- and interspecific interactions alleviated the decrease of root:shoot ratio by nutrient supply, which is facilitative. Wang and Callaway (2021) also reported interspecific interaction intensified increase of root:shoot ratio by drought vs. mesic conditions, which was facilitative, compared to those grown alone. The passive interspecific effects of B. pilosa implied the thriving aboveground growth of B. pilosa elicited additional aboveground growth of B. lindleyana , in order to compete for light resource. However, the belowground growth of B. lindleyana predominates over aboveground growth (Chen et al. 2024), increased proportional investment to shoots vs. roots should not be an optimal strategy for it, but strategies promoting roots vs. shoots will otherwise be more beneficial. Although previous studies suggested interspecific interaction is more beneficial in that it differs from intraspecific interaction due to lesser overlap in ecological niches and lower competitive intensity among different species (Adler et al. 2018; Wang and Callaway 2021), as well as effects of plant-soil feedbacks (PSFs). Plants will more likely be facilitated by PSFs when grown with heterospecifics (Lekberg et al. 2018), supported also by that drought increased root:shoot ratio of Potentilla recta under interspecific interaction, but decreased its root:shoot ratio under intraspecific interaction (Wang and Callaway 2021). Our results suggested, however, for both species, whether effects of interspecific interactions are beneficial or not , depend on the way of shifts in biomass allocation, or which of aboveground and belowground growth can be promoted. We not only provided evidence for effects of neighbors on plant response to light availability, but also suggested that responses of biomass allocation to abiotic and biotic factors depend on the relative strength of above- versus below-ground competition. Effects of light conditions on response to neighbors Abiotic conditions may alter responses of biomass allocation to intraspecific competition through effects on plant size and competitive intensity (Rehling et al. 2021). For example, deficiency in belowground resources can aggravate intraspecific competition, leading to pronounced decreased root: shoot ratio (Wang et al. 2017; Wang and Callaway 2021; Wang et al. 2021b; Chen et al. 2024). For aboveground resources such as light availability, we know little about its influences on plant response to conspecific neighbors (Sauter et al. 2021; Asefa et al. 2022). It is predictable that when aboveground resources are deficient, aboveground competition will become more intense, resulting in an increase in root:shoot ratio. We provided direct evidence that conspecific neighbors enhanced total mass and root:shoot ratio of Buddleja lindleyana in shade, but decreased them in full light for B. pilosa , with no effects of interspecific interaction for either species. These accorded with that plant interactions are more likely to be facilitative under environmental stress, but more likely to be competitive under more beneficial conditions (Bertness and Callaway 1994; Callaway et al. 2003; Dohn et al. 2013; Turcotte and Levine 2016; Wang and Callaway 2021). It suggested shading can promote facilitative effects of intraspecific interaction through inducing active responses or alleviating passive responses in allocation traits. However, when environmental stress is intense, such facilitative effects may disappear (Holmgren et al. 1997; Holmgren and Scheffer 2010). Chen et al. (2024) reported that intraspecific interactions suppressed total mass of B. pilosa and B. lindleyana in deficiency of nutrients, but increased their total mass when nutrients were sufficient. CONCLUSIONS Conspecific competitors weakened the trend of decreased root:shoot ratio by shade vs. full light, suggesting competitors can interfere with the process of plant foraging resources, making it more difficult or less efficient to acquire the resources for plants. We thus revised the optimal partitioning theory by demonstrating that plasticity of plant biomass allocation aimed for maximizing growth should depend on both resource availability and accessibility. Such strategy should enable enhanced efficiency of resource acquirement in face of severe environmental challenge. The two species differed in that Bidens pilosa and Buddleja lindleyana suffered more negative effects of intraspecific interaction and interspecific interaction respectively in response to full light vs. shading. These suggested whether effects of plant-plant interactions are beneficial or not depend on the way of shifts in biomass allocation, or relative strength of above- vs. belowground growth. Shading can promote facilitative effects of intraspecific interaction through inducing active responses or alleviating passive responses in allocation traits. This study emphasized the importance of investigating effects of both biotic and abiotic factors on plants, which can cause stronger environmental pressures, and thus induce more pronounced responses in plant traits. By doing this, we not only provided direct evidence for how plants deal with variations of multiple factors, but also make a revision to the optimal partitioning theory, shedding light on the intelligence of plants to cope with complex environmental changes. However we provided evidence for the strategy of plants based on one growth stage and light conditions only, more studies are needed on the dynamic patterns of how plants respond to the presence of neighbors, in the context of multiple abiotic variations, to provide further evidence for our hypothesis on plant strategy in biomass allocation. Author contributions SW and QZY conceived and designed the study. QZY, JXC, RYL, LLC, and XLH participated and performed in the experiment. QZY and SW analyzed the data. QZY wrote the manuscript, and SW edited. All authors have read and approved the final manuscript. 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ScientificWorldJournal, 2014, 473651. TABLE AND FIGURES TABLE 1 All traits used in this study and their trait, unit, abbreviations and transformation in analyses. Total mass g TM Lg Aboveground (shoot) mass g AM Lg Root mass g RM Lg Leaf mass g LM Lg Stem mass g SM Lg Petiole mass g PM Lg Stem length cm SL Lg Root shoot ratio - R/S Lg Specific leaf area cm 2 /g SLA Lg TABLE 2 Three-way ANOVA on effects of species (SP), light condition (LC), interaction strategy (IS), and their interactions on log 10 -transformed values of all traits, with the covariate (CO) being the initial size for total mass, and total biomass for all the other traits The abbreviations for all traits are in Table 1. * P < 0.05; ** P < 0.01; *** P < 0.001 CO 1 1.74 688.69*** 2120.14*** 402.14*** 642.30*** 128.13*** 12.53** 105.50*** 2.78 SP 1 11.85** 1.99 3.67 0.26 3.73 0.11 2.24 86.54*** 48.96*** LC 1 16.60*** 24.52*** 24.26*** 0.29 31.38*** 3.34 25.11*** 7.22 117.04*** IS 2 4.25* 2.93 2.43 4.41* 8.13*** 6.61** 2.83 10.35*** 12.90*** SP × LC 1 0.27 2.82 1.04 6.86* 3.41 9.72** 2.23 2.64 1.19 SP × IS 2 20.67*** 4.52* 4.02* 3.83* 0.14 0.13 4.44* 0.64 2.60 LC × IS 2 16.64*** 18.21*** 13.51*** 4.21* 5.58** 0.19 17.12*** 0.30 6.97** SP × LC × IS 2 3.01 2.58 1.33 0.21 0.31 3.24* 2.16 6.11** 1.50 FIGURE 1 Mean values (±SE) of total mass in response to no interaction (NI), intra- (INTRA) and interspecific (INTER) interactions under moderate shading (MS) and full light (FL) conditions for Buddleja lindleyana (above) and Bidens pilosa (below). Different lowercase letters indicate significant differences between interaction treatments within the same light conditions, and different uppercase letters indicate differences between light conditions within the same interaction treatments (ANCOVA, LSD, P < 0.05). FIGURE 2 Plasticity index (PI) of total mass (a, e), above-ground (b, f), root mass (c, g) and root:shoot ratio (d, h) in response to intra- (a-d) and interspecific (e-h) interactions under shade and light conditions for Buddleja lindleyana (white) and Bidens pilosa (gray). P -values indicate the significance of plasticity indexes (according to the results of ANCOVA on mean values of traits for effects of interaction strategies). FIGURE 3 Plasticity (PI) of mass traits including (a) total mass, (b) above-ground mass, (c) root mass, and (d) root:shoot ratio in response to shade vs. light conditions for Buddleja lindleyana and Bidens pilosa in treatments of no interaction (NI), intraspecific interaction (INTRA) and interspecific interaction (INTER). Supporting information Additional Supporting Information may be found in the online version of this article. Figures. S1-S2. Supplementary Material File (image1.emf) Download 78.41 KB File (image2.emf) Download 150.62 KB File (image3.emf) Download 125.37 KB File (table and figures.docx) Download 148.49 KB Information & Authors Information Version history V1 Version 1 18 February 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords ecological experiment laboratory plants population ecology Authors Affiliations Qingzhu Yang 0009-0000-3413-8284 Guizhou University View all articles by this author Shu Wang 0000-0002-5353-6744 [email protected] Guizhou University View all articles by this author Jia Chen Guizhou University View all articles by this author Renya Yin Guizhou University View all articles by this author Linli Chen Guizhou University View all articles by this author xia Hou 0009-0003-6471-1573 Guizhou University View all articles by this author Metrics & Citations Metrics Article Usage 294 views 128 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Qingzhu Yang, Shu Wang, Jia Chen, et al. Complex plasticity in biomass allocation in response to light availability and plant-plant interactions. Authorea . 18 February 2025. 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