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Knowledge of how agricultural management interacts with weed seed banks and emergent weed communities is crucial for proactive weed management. Though studies have detailed how differences in disturbance and nutrient applications between organic and conventional herbicide‐based systems affect weed communities, few have focused on these same factors in contrasting organic systems. This study assessed the seed banks and emergent weed communities from the most recent crop rotation cycle (2017–2022) of a long‐term experiment, which compared four organic grain and forage cropping systems differing in nutrient inputs and soil disturbance. The high fertility (HF) system received high‐rate nutrient applications, low fertility (LF) received low‐rate applications, enhanced weed management (EWM) focused on weed control through frequent soil disturbance, and reduced tillage (RT) prioritized soil health with less intense or frequent soil disturbance. Soil samples for greenhouse germination assays were collected at the beginning (2017) and end (2022) of the rotation to explore how these four systems influenced seed bank dynamics over time. Weed community biomass was also sampled in each crop during this time. Treatment effects on weed abundance, taxonomic diversity, and community‐weighted means and functional dispersion of weed traits were analyzed with generalized mixed‐effect models. The RT system had the highest weed seed bank taxonomic diversity, and EWM had the lowest. RT and LF had higher functional dispersion of traits than HF in the seed bank. Weed seed bank communities in HF and RT were characterized by short, small‐seeded, and early germinating weed species. However, seed banks were also labile: Differences between systems in seed density and all other mean trait values were dependent on the crop, which preceded seed bank sampling. Likewise, differences among emergent weed communities in the four systems depended on an interaction between crop species and their planting year. Results suggest that resource availability and intensity of disturbance act as weed community assembly filters in organic cropping systems. Organic growers seeking to design systems that balance weed management and production goals can use relatively low soil disturbance and nutrient application to increase weed community taxonomic or functional diversity without necessarily increasing weed biomass or seed bank density. [ABSTRACT FROM AUTHOR]

Aims: Changes in species composition and intraspecific trait variation are recognized as potential drivers of population and community temporal dynamics but their independent and overlapping effects have not been distinguished conclusively. Our goal was to quantify the relevance of temporal vs spatial changes in species composition and intraspecific trait variations when assessing community responses to seasonality, grazing pressure and above‐ground biomass gradients. Location: Campos grassland in northeastern Uruguay. Methods: Leaf dry matter content, specific leaf area, leaf width and tensile strength of dominant grass species were assessed across summer–autumn, winter, and spring seasons, under two grazing pressures. Species composition and above‐ground biomass were estimated in 20 × 20‐cm permanent quadrats within each season. Species trait variability was decomposed across space and time using hierarchical linear mixed models, while the spatio‐temporal community functional variation was decomposed into species turnover (abundance and/or species identity shifts) and intraspecific trait variation. Additionally, we explored the relevance of including or not including temporal intraspecific trait variation on community responses to seasonality, above‐ground biomass and grazing pressure using linear mixed models. Results: Intraspecific trait variation explained 22.4%–66.5% of total trait variability, and it was generally more important across time than space, which accounted for 12.2%–57.7% of total variability. The within‐species trait variability was generally more important than species turnover in explaining the community spatio‐temporal functional variation. In general, seasonality more strongly caused intraspecific changes while the above‐ground biomass gradient caused species turnover. Functional community responses to grazing pressure, above‐ground biomass and seasonality were affected by considering or not considering intraspecific trait variation. Conclusions: Trait variation within species across seasons is at least equally important as variation within species across space. Its influence in the functional changes of vegetation should not be considered only along environmental gradients but also through time. [ABSTRACT FROM AUTHOR]

Ungulate grazing involves multiple components, including defoliation, dung and urine return, and trampling, which supply offsetting or synergistic effects on plant community composition and productivity (ANPP), but these effects have not been fully studied. Plant functional traits may reflect the response of plants to disturbance and their impact on ecosystem functions. Species turnover and intraspecific trait variation (ITV) are important drivers of community trait composition. We conducted a simulated grazing experiment in a steppe grassland in northern China to examine the effects of defoliation, dung and urine return, and trampling on community-weighted mean (CWM), functional diversity (FD) and ANPP, and to disentangle the roles of species turnover and ITV in driving these changes. We found that defoliation had a dominant effect on CWMs and FDs of all four traits through species turnover and ITV, respectively, resulting in a convergence of traits towards as more resource-acquisitive strategy. Dung-urine return resulted in more resource-acquisitive community traits mainly through ITV, whereas there were no significant effects on FDs except for leaf C/N. Trampling increased CWM of leaf dry matter content primarily driven by ITV, and had no significant effect on FDs. Furthermore, our simulated grazing positively affected ANPP, primarily due to nutrient additions from dung and urine, and ITV largely explained the variation in ANPP. These findings highlight the multifaceted effects of grazing components on community structure and ANPP, and the significance of ITV in shaping grassland plant communities and productivity. [ABSTRACT FROM AUTHOR]

Changes in climate and grazing intensity influence plant-community compositions and their functional structure. Yet, little is known about their possible interactive effects when climate change mainly has consequences during the growing season and grazing occurs off growing season (dormant season grazing). We examined the contribution of trait plasticity to the immediate responses in the functional structure of plant community due to the interplay between these two temporally disjunct drivers. We conducted a field experiment in the northern Mongolian steppe, where climate was manipulated by open-top chambers (OTCs) for two growing seasons, increasing temperature and decreasing soil moisture (i.e., increased aridity), and grazing was excluded for one dormant season between these two growing seasons. We calculated the community-weighted mean (CWM) and the functional diversity (FD) of six leaf traits. Based on a variance partitioning approach, we evaluated how much of the responses in CWM and FD to OTCs and dormant season grazing occur through plasticity. The interactive effect of OTCs and the dormant season grazing were detected only after considering the role of trait plasticity. Overall, OTCs influenced the responses in CWM more than in FD, but the effects of OTCs were much less pronounced where dormant season grazing occurred. Thus, warming (together with decreased soil moisture) and the elimination of dormant season grazing could interact to impact the functional trait structure of plant communities through trait plasticity. Climate change effects should be considered in the context of altered land use, even if temporally disjunct. [ABSTRACT FROM AUTHOR]

One of the main management strategies of China's nature reserve is "zonation", dividing reserves into three zones (core, buffer, and experimental zones) to which different levels of restrictions on anthropogenic activities are applied. While zonation has a positive effect on the conservation of target species, it is unclear whether management zones can be effective in conserving biodiversity. Using bird data collected from five national nature reserves of Guangdong province in China during 2018–2019, we investigated how management zones and reserves are associated with bird diversity and community composition. We considered species richness, the community-weighted mean (CWM) values of 10 single traits, and beta diversity based on 2 dissimilarity indices (Jaccard and Bray–Curtis). The overall effects of zone management were weak or insignificant. Species richness and the CWMs of most traits were not associated with zone (p > 0.08). Reserve itself was a strong factor influencing bird traits. Dissimilarity indices also showed variations in bird community composition between reserves in the north region and those in the south region, which were largely contributed by the turnover component of beta diversity (p ≥ 0.06 for nestedness and p ≤ 0.03 for turnover in both dissimilarity indices). The dominance of turnover indicates that these reserves could be equally important to maintain regional bird diversity, requiring a multiple-site management plan. Our study also suggests that current zoning designations of the five reserves may not be as effective in conserving bird species diversity and traits; however, caution is needed due to the limitations of our study design, such as potential observer effect and insufficient sampling effort. [ABSTRACT FROM AUTHOR]

Abstract Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency. Nitrogen (N) deposition is a crucial component of the global N cycling. Nematode body size is a trait that responds to climate change and is used as a standard trait-based indicator in soil community analysis. Variations in body size influence metabolic carbon (C). We examined the ways by which body size and metabolic C of nematodes respond to changing precipitation regimes and how N deposition regulates these responses by an 8-year manipulative experiment. Methods Nematode body size was indicated by the community-weighted mean (CWM) mass. We quantified C metabolism components of soil nematodes including production C, respiration C, and corresponding C use efficiency (CUE) under different precipitation intensities and N addition in a semi-arid steppe on the Mongolian Plateau. The Mantel test was used to determine the correlations between CWM, CUE and environmental factors. The partial least squares path modeling (PLS-PM) was conducted to quantify direct or indirect contributions among latent variables. Results We found that heavy precipitation intensity increased the CWM mass of total nematodes and omnivores-predators without N addition. N addition decreased CWM mass of bacterivores across all the precipitation intensity treatments. Stronger precipitation intensities might be favorable for nematode production and respiration C. Variations in the nematode CWM mass drove the CUE to change with N addition. Conclusions Our findings provide new insights into the mechanisms underlying nematode body size and C metabolism, and highlight that explorative studies, such as manipulative experiments, are needed to identify traits underlying size-related effects and to investigate how they affect CUE of nematodes. These efforts may increase our understanding of how changes in precipitation regimes and N deposition may alter soil nematode communities in grassland ecosystems.

In biodiversity conservation frameworks, determining surrogates for biodiversity is crucial for improving the effectiveness of biodiversity conservation and management. As plant functional composition can indicate variations in ecosystem functions and services, it could be used as an effective surrogate in biodiversity conservation planning. However, to the best of our knowledge, this metric has been rarely used in biodiversity conservation planning. To explore whether plant functional composition can be used as an effective surrogate for biodiversity conservation, we used a linear mixed regression model to investigate the relationships between plant functional composition (i.e., community-weighted means (CWMs) from the sPlot database) and the species richness of birds, mammals, and amphibians, and between plant functional composition and terrestrial conservation priority ranks (considering biodiversity conservation alone, or biodiversity, carbon, and water conservation together). Thereafter, we quantified the changing trends in these relationships across biomes using the least square method. We found that CWMs significantly affected species richness and terrestrial conservation priority ranks, based on the marginal R2 and conditional R2 values from the linear mixed regression model. Further, CWMs significantly affected species richness and terrestrial conservation priority ranks across different biomes of forests and shrublands. However, the nature of these effects (i.e., positive or negative) was dependent on biome type. These results suggest that functional composition can be considered as a biodiversity surrogate for conservation planning, and that biome-specific relationships should be considered.

Aim: The microclimate and light conditions on the forest floor are strongly modified by tree canopies. Therefore, we need to better consider the micro‐environment when quantifying trait–environment relationships for forest understorey plants. Here, we quantify relationships between micro‐environmental conditions and plant functional traits at the community level, including intraspecific trait variation, and their relationship with microclimate air temperature, light and soil properties. Location: Deciduous temperate forests across Europe. Time period: 2018. Major taxa studied: Herbaceous vegetation. Methods: We sampled 225 plots across 15 regions along four complementary gradients capturing both macro‐ and microclimatic conditions including latitude, elevation, forest management and distance to forest edges. We related the community‐weighted mean of five plant functional traits (plant height, specific leaf area [SLA], plant carbon [C], plant nitrogen [N] and plant C:N ratio) across 150 vascular plant species to variation in local microclimate air temperature, light and soil properties. We tested the effect of accounting for intraspecific variation in trait–environment relationships and performed variation partitioning to identify major drivers of trait variation. Results: Microclimate temperature, light availability and soil properties were all important predictors of community‐weighted mean functional traits. When light availability and variation in temperature were higher, the herb community often consisted of taller plants with a higher C:N ratio. In more productive environments (e.g. with high soil nitrogen availability), the community was dominated by individuals with resource‐acquisitive traits: high SLA and N but low C:N. Including intraspecific trait variation increased the strength of the trait–micro‐environment relationship, and increased the importance of light availability. Main conclusions: The trait–environment relationships were much stronger when the micro‐environment and intraspecific trait variation were considered. By locally steering light availability and temperature, forest managers can potentially impact the functional signature of the forest herb‐layer community. [ABSTRACT FROM AUTHOR]

In biodiversity conservation frameworks, determining surrogates for biodiversity is crucial for improving the effectiveness of biodiversity conservation and management. As plant functional composition can indicate variations in ecosystem functions and services, it could be used as an effective surrogate in biodiversity conservation planning. However, to the best of our knowledge, this metric has been rarely used in biodiversity conservation planning. To explore whether plant functional composition can be used as an effective surrogate for biodiversity conservation, we used a linear mixed regression model to investigate the relationships between plant functional composition (i.e., community-weighted means (CWMs) from the sPlot database) and the species richness of birds, mammals, and amphibians, and between plant functional composition and terrestrial conservation priority ranks (considering biodiversity conservation alone, or biodiversity, carbon, and water conservation together). Thereafter, we quantified the changing trends in these relationships across biomes using the least square method. We found that CWMs significantly affected species richness and terrestrial conservation priority ranks, based on the marginal R2 and conditional R2 values from the linear mixed regression model. Further, CWMs significantly affected species richness and terrestrial conservation priority ranks across different biomes of forests and shrublands. However, the nature of these effects (i.e., positive or negative) was dependent on biome type. These results suggest that functional composition can be considered as a biodiversity surrogate for conservation planning, and that biome-specific relationships should be considered. [ABSTRACT FROM AUTHOR]

Background: Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency. Nitrogen (N) deposition is a crucial component of the global N cycling. Nematode body size is a trait that responds to climate change and is used as a standard trait-based indicator in soil community analysis. Variations in body size influence metabolic carbon (C). We examined the ways by which body size and metabolic C of nematodes respond to changing precipitation regimes and how N deposition regulates these responses by an 8-year manipulative experiment. Methods: Nematode body size was indicated by the community-weighted mean (CWM) mass. We quantified C metabolism components of soil nematodes including production C, respiration C, and corresponding C use efficiency (CUE) under different precipitation intensities and N addition in a semi-arid steppe on the Mongolian Plateau. The Mantel test was used to determine the correlations between CWM, CUE and environmental factors. The partial least squares path modeling (PLS-PM) was conducted to quantify direct or indirect contributions among latent variables. Results: We found that heavy precipitation intensity increased the CWM mass of total nematodes and omnivores-predators without N addition. N addition decreased CWM mass of bacterivores across all the precipitation intensity treatments. Stronger precipitation intensities might be favorable for nematode production and respiration C. Variations in the nematode CWM mass drove the CUE to change with N addition. Conclusions: Our findings provide new insights into the mechanisms underlying nematode body size and C metabolism, and highlight that explorative studies, such as manipulative experiments, are needed to identify traits underlying size-related effects and to investigate how they affect CUE of nematodes. These efforts may increase our understanding of how changes in precipitation regimes and N deposition may alter soil nematode communities in grassland ecosystems. [ABSTRACT FROM AUTHOR]

Periphytic rotifer assemblages from lentic habitats are understudied. To improve knowledge on the principal environmental determinants of their structure and composition, we examined summer periphyton from 184 freshwater bodies from a taxonomic and multi-trait-based perspective. Only the latter allowed consideration of all bdelloids. Alpha diversity decreased with electrolyte and aluminium concentration but increased with macrophyte richness, pointing at salinization, metal toxicity and loss of structural niche heterogeneity as potential threats for rotifer diversity. Replacement was the prominent component of beta diversity, with acidified sites showing the highest local contributions. Variation partitioning indicated that local conditions explained variation in species composition best, but general setting (soil type, land cover, connectivity) and spatial context were also not insignificant. Redundancy analysis related species composition more particularly to gradients of pH and trophic status, whereas the representation of functional groups was structured mainly by phytoplankton productivity. Mirroring shifts observed in the plankton, high phytoplankton productivity associated with larger size and more detritibacterivory. Dominance of collectors constrained variation in guild ratios, underlining the need for more refined functional approaches. To aid the use of periphytic rotifers in regional water quality assessment, we identified indicators and community thresholds for pH and trophic variables and determined optima and tolerances for individual taxa. [ABSTRACT FROM AUTHOR]

Abstract Estimating phenotypic distributions of populations and communities is central to many questions in ecology and evolution. These distributions can be characterized by their moments (mean, variance, skewness and kurtosis) or diversity metrics (e.g. functional richness). Typically, such moments and metrics are calculated using community‐weighted approaches (e.g. abundance‐weighted mean). We propose an alternative bootstrapping approach that allows flexibility in trait sampling and explicit incorporation of intraspecific variation, and show that this approach significantly improves estimation while allowing us to quantify uncertainty. We assess the performance of different approaches for estimating the moments of trait distributions across various sampling scenarios, taxa and datasets by comparing estimates derived from simulated samples with the true values calculated from full datasets. Simulations differ in sampling intensity (individuals per species), sampling biases (abundance, size), trait data source (local vs. global) and estimation method (two types of community‐weighting, two types of bootstrapping). We introduce the traitstrap R package, which contains a modular and extensible set of bootstrapping and weighted‐averaging functions that use community composition and trait data to estimate the moments of community trait distributions with their uncertainty. Importantly, the first function in the workflow, trait_fill, allows the user to specify hierarchical structures (e.g. plot within site, experiment vs. control, species within genus) to assign trait values to each taxon in each community sample. Across all taxa, simulations and metrics, bootstrapping approaches were more accurate and less biased than community‐weighted approaches. With bootstrapping, a sample size of 9 or more measurements per species per trait generally included the true mean within the 95% CI. It reduced average percent errors by 26%–74% relative to community‐weighting. Random sampling across all species outperformed both size‐ and abundance‐biased sampling. Our results suggest randomly sampling ~9 individuals per sampling unit and species, covering all species in the community and analysing the data using nonparametric bootstrapping generally enable reliable inference on trait distributions, including the central moments, of communities. By providing better estimates of community trait distributions, bootstrapping approaches can improve our ability to link traits to both the processes that generate them and their effects on ecosystems.

Questions: Trait–environment relationships hold great promise for elucidating the mechanisms that drive community assembly. We asked to what extent does functional trait coordination underlie the differentiation of acquisitive–conservative strategies along environmental gradients? Also, to what extent does soil water availability determine trait combinations and subsequently shape microhabitat preferences for species with distinct ecological strategies? Location: Yunnan Province, southwest China. Methods: Pearson correlation and trait network analyses were used to quantify trait associations. A combined RLQ–fourth‐corner analysis and a spatial autoregressive error model were employed to examine trait–environment relationships and explain species distribution along environmental gradients. Results: Leaf and stem traits were tightly coordinated along the first RLQ axis. Herein, traits representing construction cost exhibited trade‐offs against traits representing resource acquisition rate, underlying an acquisitive–conservative strategy differentiation along the environmental gradients. Significant overall and bivariate trait–environment relationships were found. In addition, the topographic wetness index contributed substantially to the environmental variation, and significantly influenced most traits alone. These results supported the hypothesis that soil water availability was the key environmental factor in selecting trait combinations and driving the differentiation of acquisitive and conservative strategies for coexisting species compared with other environmental factors. Finally, deciduous and a proportion of the evergreen species were acquisitive, whereas the remaining evergreen species were conservative, preferring wetter and drier microhabitats, respectively. Conclusions: Our findings indicate that soil water availability plays a central role in shaping both the trait combinations and microhabitat preferences of species with different ecological strategies rather than different leaf habits. These findings also highlight the fundamental significance of functional traits in facilitating the differentiation between acquisitive and conservative strategies along environmental gradients. [ABSTRACT FROM AUTHOR]

Plant species composition and structural attributes are related to physiographic factors such as slope orientation and topographic position. This relationship is accentuated with increasing seasonality in temperature and precipitation. We quantified the relationship between topography and the taxonomic, functional and phylogenetic community composition of woody species at the northernmost distribution of seasonally dry tropical forests (STDF) in the Americas. We related slope orientation (north-facing vs. south-facing) and position (upper slope vs. lower slope) to the distribution of species, assessed their habitat preference by life stage (juvenile vs. adult) and compared the observed phylogenetic distance of species against random species assemblages. Our results showed the segregation of two species groups in both life stages is related to slope orientation, but not to topographic position. We found a strong habitat association for 68% of the species with both juveniles and adults similarly associated with the same habitat. Slope orientation was related to taxonomic, functional and phylogenetic structure, but it differed in the two life stages. The functional and evolutionary segregation of species between north-facing vs. south-facing habitats indicates that species are non-randomly distributed; suggesting that deterministic mechanisms (e.g. topographic habitat specialisation) are operating at a local scale. Slope orientation drives the species-habitat association, and functional/phylogenetic structure of the northernmost tropical dry forests on the American continent. Juveniles and adults of tree species share similar habitat association patterns, conserving habitat preference. In both life stages, the functional and phylogenetic structure of trees was clearly differentiated between north-facing and south-facing slopes, but similar within each slope. Dry forest tree species are non-randomly distributed among topographic habitats. The contrasting periods of water availability in the soil and solar radiation between slopes have revealed emerging patterns of topographic habitat specialisation. [ABSTRACT FROM AUTHOR]

Estimating phenotypic distributions of populations and communities is central to many questions in ecology and evolution. These distributions can be characterized by their moments (mean, variance, skewness and kurtosis) or diversity metrics (e.g. functional richness). Typically, such moments and metrics are calculated using community‐weighted approaches (e.g. abundance‐weighted mean). We propose an alternative bootstrapping approach that allows flexibility in trait sampling and explicit incorporation of intraspecific variation, and show that this approach significantly improves estimation while allowing us to quantify uncertainty.We assess the performance of different approaches for estimating the moments of trait distributions across various sampling scenarios, taxa and datasets by comparing estimates derived from simulated samples with the true values calculated from full datasets. Simulations differ in sampling intensity (individuals per species), sampling biases (abundance, size), trait data source (local vs. global) and estimation method (two types of community‐weighting, two types of bootstrapping).We introduce the traitstrap R package, which contains a modular and extensible set of bootstrapping and weighted‐averaging functions that use community composition and trait data to estimate the moments of community trait distributions with their uncertainty. Importantly, the first function in the workflow, trait_fill, allows the user to specify hierarchical structures (e.g. plot within site, experiment vs. control, species within genus) to assign trait values to each taxon in each community sample.Across all taxa, simulations and metrics, bootstrapping approaches were more accurate and less biased than community‐weighted approaches. With bootstrapping, a sample size of 9 or more measurements per species per trait generally included the true mean within the 95% CI. It reduced average percent errors by 26%–74% relative to community‐weighting. Random sampling across all species outperformed both size‐ and abundance‐biased sampling.Our results suggest randomly sampling ~9 individuals per sampling unit and species, covering all species in the community and analysing the data using nonparametric bootstrapping generally enable reliable inference on trait distributions, including the central moments, of communities. By providing better estimates of community trait distributions, bootstrapping approaches can improve our ability to link traits to both the processes that generate them and their effects on ecosystems. [ABSTRACT FROM AUTHOR]

The functional composition of plant communities (FCPC) makes a significant contribution to ecosystem properties, functions, and services. Here, we used 18 plant functional traits from the sPlot database v2.1 and the global forest management type dataset to explore the links between forest management and the FCPC. We used the post hoc Tukey test to explore the differences in the community-weighted mean (CWM) and community-weighted variance (CWV) among different forest management types [i.e., intact forests, managed forests with natural regeneration, planted forests, plantation forests (with up to a 15-year rotation), and agroforestry]. We found that different forest management types can result in significant variability in plant communities' functional composition. Plantation forests could result in significantly higher CWM and CWV compared to intact forests, and significant differences could occur between natural and managed forests with natural regeneration. Furthermore, the relationship between forest management practices and the FCPC depends on ecozone type changes. There were significant differences between natural and plantation forests for CWM and CWV in temperate forests. Our study provides an effective reference for applying plant functional traits to regulate and optimize the functions and services of forest ecosystems. [ABSTRACT FROM AUTHOR]

Aboveground, large and higher trophic‐level organisms often respond more strongly to environmental changes than small and lower trophic‐level organisms. However, whether this trophic or size‐dependent sensitivity also applies to the most abundant animals, microscopic soil‐borne nematodes, remains largely unknown. Here, we sampled an altitudinal transect across the Tibetan Plateau and applied a community‐weighted mean (CWM) approach to test how differences in climatic and edaphic properties affect nematode CWM biomass at the level of community, trophic group and taxon mean biomass within trophic groups. We found that climatic and edaphic properties, particularly soil water‐related properties, positively affected nematode CWM biomass, with no overall impact of altitude on nematode CWM biomass. Higher trophic‐level omnivorous and predatory nematodes responded more strongly to climatic and edaphic properties, particularly to temperature, soil pH, and soil water content than lower trophic‐level bacterivorous and fungivorous nematodes. However, these differences were likely not (only) driven by size, as we did not observe significant interactions between climatic and edaphic properties and mean biomasses within trophic groups. Together, our research implies a stronger, size‐independent trophic sensitivity of higher trophic‐level nematodes compared with lower trophic‐level ones. Therefore, our findings provide new insights into the mechanisms underlying nematode body size structure in alpine grasslands and highlight that traits independent of size need to be found to explain increased sensitivity of higher trophic‐level nematodes to climatic and edaphic properties, which might affect soil functioning. [ABSTRACT FROM AUTHOR]

One of the main management strategies of China’s nature reserve is “zonation”, dividing reserves into three zones (core, buffer, and experimental zones) to which different levels of restrictions on anthropogenic activities are applied. While zonation has a positive effect on the conservation of target species, it is unclear whether management zones can be effective in conserving biodiversity. Using bird data collected from five national nature reserves of Guangdong province in China during 2018–2019, we investigated how management zones and reserves are associated with bird diversity and community composition. We considered species richness, the community-weighted mean (CWM) values of 10 single traits, and beta diversity based on 2 dissimilarity indices (Jaccard and Bray–Curtis). The overall effects of zone management were weak or insignificant. Species richness and the CWMs of most traits were not associated with zone (p > 0.08). Reserve itself was a strong factor influencing bird traits. Dissimilarity indices also showed variations in bird community composition between reserves in the north region and those in the south region, which were largely contributed by the turnover component of beta diversity (p ≥ 0.06 for nestedness and p ≤ 0.03 for turnover in both dissimilarity indices). The dominance of turnover indicates that these reserves could be equally important to maintain regional bird diversity, requiring a multiple-site management plan. Our study also suggests that current zoning designations of the five reserves may not be as effective in conserving bird species diversity and traits; however, caution is needed due to the limitations of our study design, such as potential observer effect and insufficient sampling effort.

IntroductionPlant diversity and soil chemical properties are important factors affecting the plant growth. We sought to compare the explanatory rates of diversity and soil chemical properties in explaining the variation of basal area in karst forests, and also sought to compare the relative importance of the niche complementarity and mass ratio hypotheses.MethodsOn the basis of linear regression and structural equation modelling, we examined the correlation between the basal area of plant communities and species diversity, functional diversity, phylogenetic diversity, the community-weighted mean (CWM) of traits, and soil chemical properties, using data obtained from 35 monitoring plots in southwest China.ResultsSpecies, functional, and phylogenetic diversities were all significantly correlated with the basal area of the plant community, among the indices of which, Faith’s phylogenetic diversity was found to have the greatest explanatory power for basal area. These plant diversity indices can better explain the variation in basal area than the CWM of traits, suggesting the niche complementarity hypothesis is more applicable than the mass ratio hypothesis. Moreover, soil chemical properties also have an equal important impact. Different chemical properties were found to show significant positive correlations with basal area, and their total effects on basal area were shown to be greater than the CWM of traits.DiscussionAttention should be paid to diversity and soil chemical properties. This study provides theoretical guidance for understanding biodiversity maintenance mechanisms and protecting karst forests.

Upscaling trait‐based restoration to regional levels is necessary as we enter the UN Decade on Ecosystem Restoration. For this, we need to select species that achieve functional targets considering the regional species pool.Here, we present a framework to achieve multiple restoration targets using a regional species pool containing the species available on the market, species unavailable, and species that occur in reference ecosystems. The framework enables optimising functional diversity (FD), recovering FD and composition using reference ecosystems, reducing cost and increasing species diversity in restoration. Additionally, our framework allows the detection of functionally relevant species in the regional pool that are unavailable for restoration on the market. We illustrate our framework with a data set of Brazilian savanna tree communities.It was not possible to optimise FD with the species available on the market. To achieve this target, it would be necessary to use unavailable species from the regional pool. However, with the species available on the market it was possible to obtain communities resistant to fire and to restore functional composition and diversity to levels similar to or greater than those observed in reference ecosystems.Synthesis and applications. Our framework selects species to achieve multiple targets in large‐scale trait‐based restoration initiatives. The framework shows a range of solutions that can be achieved with the regional species pool. That allows the restoration practitioner to verify if functional parameters are truly optimised and which species should be added to the market or collected from the wild to achieve restoration targets. It also shows how different selected communities are from reference ecosystems, avoiding the unintentional creation of novel ecosystems. [ABSTRACT FROM AUTHOR]

Aim: Attempts over the past 30 years to explain geographical variation in the strength of herbivore pressure have given rise to ecological hypotheses like the latitudinal herbivory hypothesis. This hypothesis, however, has rarely been tested using community‐level data. Therefore, the aim of our study was to examine the patterns and potential mechanisms underlying geographical variation in community‐wide herbivory. Location: The Qinghai‐Tibetan Plateau. Time Period: July 2021. Major Taxa Studied: Plants. Methods: We selected 43 grassland sites along a 1500‐km latitudinal gradient (c. 27°N to 39°N) and a 2698‐m elevational gradient (1886–4584 m) on the Qinghai‐Tibetan Plateau. We evaluated geographical patterns in invertebrate herbivory pressure at the population and community levels, while also evaluating the importance of geographical variation in mediating the effects of abiotic and biotic factors on intraspecific variation (through changes in herbivory on component species) and species turnover effects (through changes in plant community composition). Results: Community‐wide herbivory decreased with latitude, mirroring intraspecific variation, while species turnover effects did not vary along any tested geographical gradients. Furthermore, we found that geographical variation in community‐wide herbivory was strongly positively correlated with soil nitrogen content. We also found a positive effect of soil nitrogen content on intraspecific variation and a negative effect of plant community biomass on species turnover effects. Main Conclusions: The latitudinal gradient in community‐wide herbivory was primarily mediated by intraspecific variation, which was in turn associated with a gradient in soil nitrogen content. Our findings highlight the need for community‐wide assessments of geographical variation in plant–herbivore interactions, decomposing community‐wide herbivory into intraspecific variation and species turnover effects. [ABSTRACT FROM AUTHOR]

Aim: Theoretical, experimental and observational studies have shown that biodiversity–ecosystem functioning (BEF) relationships are influenced by functional community structure through two mutually non‐exclusive mechanisms: (1) the dominance effect (which relates to the traits of the dominant species); and (2) the niche partitioning effect [which relates to functional diversity (FD)]. Although both mechanisms have been studied in plant communities and experiments at small spatial extents, it remains unclear whether evidence from small‐extent case studies translates into a generalizable macroecological pattern. Here, we evaluate dominance and niche partitioning effects simultaneously in grassland systems world‐wide. Location: Two thousand nine hundred and forty‐one grassland plots globally. Time period: 2000–2014. Major taxa studied: Vascular plants. Methods: We obtained plot‐based data on functional community structure from the global vegetation plot database "sPlot", which combines species composition with plant trait data from the "TRY" database. We used data on the community‐weighted mean (CWM) and FD for 18 ecologically relevant plant traits. As an indicator of primary productivity, we extracted the satellite‐derived normalized difference vegetation index (NDVI) from MODIS. Using generalized additive models and deviation partitioning, we estimated the contributions of trait CWM and FD to the variation in annual maximum NDVI, while controlling for climatic variables and spatial structure. Results: Grassland communities dominated by relatively tall species with acquisitive traits had higher NDVI values, suggesting the prevalence of dominance effects for BEF relationships. We found no support for niche partitioning for the functional traits analysed, because NDVI remained unaffected by FD. Most of the predictive power of traits was shared by climatic predictors and spatial coordinates. This highlights the importance of community assembly processes for BEF relationships in natural communities. Main conclusions: Our analysis provides empirical evidence that plant functional community structure and global patterns in primary productivity are linked through the resource economics and size traits of the dominant species. This is an important test of the hypotheses underlying BEF relationships at the global scale. [ABSTRACT FROM AUTHOR]

Although an increasing amount of attention is being paid to how human activities alter plant communities, little is known about the consequences of these changes on species' assemblages and biodiversity patterns. Using three forest types (a Pinus yunnanensis man-made forest; Eucalyptus smithii man-made forest; and natural secondary forest) in mid-Yunnan, China, we investigated the distribution patterns of species and traits and analyzed diversity patterns and relationships, including those between species diversity, functional diversity, and soil microbial diversity. We found that species co-occurrence patterns in the Pinus yunnanensis man-made forest and natural secondary forest were non-random. The specific leaf area in the Eucalyptus smithii man-made forest and leaf nitrogen concentration in the Pinus yunnanensis man-made forest were both over-dispersed according to the mean Euclidean neighbor distance in the trait space. The natural secondary forest had higher values of species diversity, functional diversity, community-weighted means, and soil microbial diversity than the man-made forest types did. An overall low covariation between species diversity and community-weighted means suggested that the coexistence of many species does not necessarily support functional differentiation among these species. Variance partitioning revealed that soil microbial diversity was mainly regulated by community-weighted means. In conclusion, our results suggest that the naturally recovering forest was better than man-made plantations based on biodiversity patterns. [ABSTRACT FROM AUTHOR]

Simple Summary: Successful restoration requires evaluating the patterns and driving factors of functional characteristics under different land restoration types. The functional properties of communities are frequently quantified using functional diversity (FD) and the community-weighted mean (CWM). Changes in functional characteristics in different restoration communities are influenced not only by species attributes but also by site environmental conditions. However, the patterns and driving factors of functional characteristics have been poorly explored. Here, we investigated species diversity, functional characteristics, and soil physicochemical properties across four vegetation restoration types. We found that different restoration communities significantly altered most community structures and functional properties in terms of species diversity, FD, and CWM. Most of the variation in functional characteristics was explained by soil physicochemical properties, especially SWC and AP. Moreover, the linkages between CWMs and soil properties were stronger than those between FD and soil properties. These results indicated that SWC and AP, as habitat filters, regulated the patterns of functional characteristics by changing the dominant species and their functional traits. Functional characteristics are increasingly used to evaluate the success of different vegetation restoration. Community functional diversity (FD) and the community-weighted mean (CWM), as two main complementary components, are closely linked to site environment and ecosystem functions. However, the patterns and driving factors of functional characteristics are still not clear in different vegetation restoration types. Here, four community restoration types (secondary shrubland, SL; Pinus yunnanensis forest, PF; mixed needle–broad-leaved forest, MF; natural secondary forest, NSF) were selected to investigate species diversity, FD, CWM, and soil physicochemical properties. The relative effects of species diversity and soil abiotic features on variation in functional characteristics were then evaluated. We found that different restoration communities altered most community structures and functional properties in terms of species diversity, FD, and CWM. CWM values and FD in different communities presented different distribution patterns depending on certain traits and parameters. Significant correlations between functional traits were found at the species and community scales, suggesting a potential covariation between these selected traits in communities. The results of redundancy analysis and variation partitioning showed that most of the variation in functional characteristics, especially CWM, was explained by soil moisture and available phosphorus, indicating that habitat filters regulate the functional characteristics of plant communities mainly by changing the dominant species composition and functional traits of species. Therefore, the selection of restoration species adapted to low soil moisture and available phosphorus and the construction of communities based on selected species as the dominant species can effectively drive community assembly and ecosystem functions in the vegetation restoration process. [ABSTRACT FROM AUTHOR]

Aim: Many aspects of vegetation response to increased drought remain uncertain but it is expected that phenotypic plasticity may be key to early adaptation of plants to environmental stress. In this work we observe the response of specific leaf area (SLA) of woody shrub vegetation to the summer drought typical of the Mediterranean climate. In addition, to observe the possible interaction between the impact of drought and the environmental characteristics of the ecosystems, communities from different edaphic and structural contexts distributed along the double stress gradient of the Mediterranean mountains (high temperature and low precipitation at low elevation; low temperature and high irradiation at high elevation) have been analysed. Location: Central Mountain range of the Iberian Peninsula. Methods: Along the entire altitudinal gradient, 33 shrub communities belonging to different habitat typologies (shrublands, rocky areas, hedgerows, understorey) were sampled before and after the passage of summer, both in 2017 and 2019. A total of 1724 individuals and 15,516 leaves were collected and measured to estimate the mean values and diversity of SLA of each community. Results: The community‐weighted mean and functional divergence have inverse quadratic relationships with the environmental gradient. Shrub communities at both ends of the gradient have low mean SLA values and high functional divergence of this trait. Summer drought implies a generalised decrease in the mean SLA of the communities throughout the gradient, as well as an alteration in functional richness and uniformity. However, the effect of summer drought on the plant community is mediated by the microenvironmental characteristics of its habitat. Conclusions: Drought acclimatisation of shrub communities through phenotypic plasticity leads to rapid changes in their functional leaf structure. In the long term, our results point to an increase in plant conservative strategies, reduced ecosystem productivity, slower nutrient recycling and the reduction of communities of specific habitats as drought increases. [ABSTRACT FROM AUTHOR]

Questions: Woody encroachment in savannas has been associated with changing taxonomic composition and ecosystem function. Interestingly, there is little understanding of how encroachment impacts plant functional diversity and how those changes relate to plant demography, a crucial mediator between taxonomic composition and ecosystem function. Location: Southeastern Brazil. Methods: Using a landscape scale fire suppression experiment in a diverse Brazilian savanna, we quantify how change in species composition over seven years impacted vegetative and reproductive tree functional diversity as determined by new recruits, dead and surviving trees. Results: Over seven years, tree above‐ground biomass increased by 15%, while total species richness did not change. Despite minor changes, species composition remained overall similar (82%), with few species contributing significantly to plot dissimilarity over time. There were small changes in vegetative traits, where the community‐weighted mean increased in maximum tree height (↑ 2.1%) and specific leaf area (↑ 5.3%), and decreased in wood density (↓ 1.3%) and bark thickness (↓ 9.4%). Changes in reproductive traits were larger than in vegetative traits, with an increase in the prevalence of monoecy (↑ 32.6%), dioecy (↑ 44.2%), large seeds (↑ 20.3%), animal‐mediated seed dispersal (↑ 4.9%) and pollination by very small insects (↑ 45.5%), and a decrease in the prevalence of hermaphroditism (↓ 9%), small seeds (6.8%) and pollination by small insects (12.5%). The overall decrease in bark thickness and increase in monoecy and dioecy were mainly driven by characters of the new recruits, while the overall increase in specific leaf area (SLA) and decrease in small seeds appeared largely determined by the loss of trees possessing those traits. Conclusions: Encroachment leads to changes that are likely increasing ecosystem vulnerability to fire and drought. Further, the compositional changes observed appear to drive marked change in reproductive traits, indicating increasing dependence on animals for dispersal and reproduction. Understanding post‐hoc encroachment impacts in an era of widespread pervasive encroachment is fundamental to reconciling ecosystem functions such as nutrient cycling and pollination services as there is a loss of species with open ecosystem life‐history strategies. Among savannas, there remains an urgent need to understand relationships between woody cover and ecosystem function to determine thresholds in woody cover promoting resilient savanna ecosystems. [ABSTRACT FROM AUTHOR]

In the context of tropical monsoonal dwarf forest restoration, it is well known that the interaction between soil properties and plant functional traits influences the dynamics and forest composition of plant communities. The main aim of this study was to determine the relationships and variations between the plant functional traits and environmental variables in tropical coastal secondary forests. However, it is undisputed whether trait variation is coordinated and whether there is a relationship between the community-weighted mean (CWM) traits and soil variables. TNNR conducted a ground survey to collect actual ground data on the biophysical characteristics of individual trees and shrubs, along with soil sample data. All soil samples and plant materials were collected at the end of June, in the 2020 growing season (July and August), in each quadrat with a 400-m2 area. To gain insight into these questions, a total of 4 plant functional traits of 167 species and 5 soil nutrients from 128 soil samples were analyzed from 128 plots in a tropical evergreen monsoon forest on Hainan Island. Using SMA (standardized major axis), wood density (WD), and leaf thickness (LT), as well as specific leaf area (SLA) and relative leaf water content (RLWC), were significantly positively correlated. Using Pearson correlation analysis, leaf thickness (LT) was significantly positively correlated with soil organic matter (OM). Using principal component analysis (PCA), we also found that soil TN and OM were the strongest predictors for functional traits, i.e., WD and LT. Moreover, using path analysis, OM and TN have a major impact on plant CWM traits, e.g., SLA and RLWC. Our results show a significant relationship between functional traits and soil pH and soil nutrients in tropical coastal secondary forests. Our results highlight that plant traits can be used to predict specific soil nutrients and ecosystem functioning in tropical secondary forests, but we are concerned about how variation in the physical structure of plant affect ecosystem function in forest communities. This research can help us to better understand the restoration of habitats and green infrastructure design, suggesting that selecting different species across multiple trait axes can help ensure functionality at the maximum level.

Periphytic rotifer assemblages from lentic habitats are understudied. To improve knowledge on the principal environmental determinants of their structure and composition, we examined summer periphyton from 184 freshwater bodies from a taxonomic and multi-trait-based perspective. Only the latter allowed consideration of all bdelloids. Alpha diversity decreased with electrolyte and aluminium concentration but increased with macrophyte richness, pointing at salinization, metal toxicity and loss of structural niche heterogeneity as potential threats for rotifer diversity. Replacement was the prominent component of beta diversity, with acidified sites showing the highest local contributions. Variation partitioning indicated that local conditions explained variation in species composition best, but general setting (soil type, land cover, connectivity) and spatial context were also not insignificant. Redundancy analysis related species composition more particularly to gradients of pH and trophic status, whereas the representation of functional groups was structured mainly by phytoplankton productivity. Mirroring shifts observed in the plankton, high phytoplankton productivity associated with larger size and more detritibacterivory. Dominance of collectors constrained variation in guild ratios, underlining the need for more refined functional approaches. To aid the use of periphytic rotifers in regional water quality assessment, we identified indicators and community thresholds for pH and trophic variables and determined optima and tolerances for individual taxa.

Simple Summary: Plant species of a regional flora have different ecological preferences, leading to the presence of different assemblages along environmental gradients. Botanists elaborated score systems to express species preferences for environmental factors, such as temperature, light, soil moisture, etc. The most popular system is that of the 'Ellenberg indicator values' (EIVs). EIVs have been largely applied to use plant species as indicators of environmental characteristics. In this research, we adopted a different perspective, and used EIVs to study how species are filtered by variations in ecological conditions along an elevational gradient. We used the flora of a small mountain in Central Italy as our case study. We found that heat-loving species are progressively replaced by cold-adapted ones at increasing elevations. Sunlight-adapted species prevail at low and high elevations (where open habitats occur), whereas in the middle of the gradient (occupied by the beech forest) shade-loving species predominate. Variation for moisture and soil nutrient preferences followed a similar pattern since humus abundance makes forest soils moister and richer in nutrients. Preferences for pH and continentality did not follow any clear pattern, since these factors are subject to more local variations. These results highlight the possible use of EIVs to study how plant communities respond to environmental gradients. Ellenberg indicator values (EIVs) express plant preferences for temperature, light, continentality, soil moisture, pH, and soil nutrients, and have been largely used to deduce environmental characteristics from plant communities. However, EIVs might also be used to investigate the importance of filtering mechanisms in shaping plant communities according to species ecological preferences, a so far overlooked use of EIVs. In this paper, we investigated how community-weighted means (CWM), calculated with EIVs, varied along an elevational gradient in a small mountain in Central Italy. We also tested if species abundances varied according to their ecological preferences. We found that the prevalence of thermophilous species declines with elevation, being progressively replaced by cold-adapted species. Heliophilous species prevail at low and high elevations (characterized by the presence of open habitats), whereas in the middle of the gradient (occupied by the beech forest), sciophilous species predominate. Variations for moisture and soil nutrient preferences followed a similar pattern, probably because of the high moisture and nutrient levels of forest soils with a lot of humus. No distinct pattern was detected for EIVs for pH and continentality since these factors are subject to more local variations. These results highlight the possible role of EIVs to investigate how environmental gradients shape plant communities. [ABSTRACT FROM AUTHOR]

The 'mass ratio' hypothesis states that ecosystem functioning is driven by the functional traits of the most dominant species in communities. Thus, we aimed to evaluate (i) How topographical conditions and stand age determine changes in tree community composition, richness, abundance and carbon dominant (CD) species, and (ii) Assess whether community-weighted mean of functional trait values of CD species explain aboveground carbon (AGC) stock. We used community-weighted mean of wood density and maximum stem diameter to evaluate the effect of functional dominance in AGC stock. We found that different topographic conditions and stand age change community composition, richness, abundance and CD species along the late-secondary stage. Our results showed that functional trait values of CD species determine AGC stock. Thus, the proportion of CD species was shaped by topography and stand age, whereas carbon stock by the dominant species' functional traits (wood density and diameter). This study advances our understanding of the mechanisms that drive carbon stock in tropical forests and supports the 'mass ratio' hypothesis. We emphasize the relevance of the trait-based approach to understand forest functioning and trait functional composition and taxonomic identity for carbon storage, recovery and increase in secondary Atlantic Forests. [ABSTRACT FROM AUTHOR]

Questions: Evaluating reasons for the success (or failure) of restoration projects is one of the major goals for applied ecologists in the context of the dramatic worldwide decline in biodiversity. To that end, finding appropriate indicators and reference ecosystems is mandatory, especially for habitats in which restoration projects have been barely evaluated over the long term, such as coastal sand dunes. Do different indicators provide complementary information to evaluate restoration success? How successful is sand dune restoration after 30 years? Location: Brittany (France). Methods: We report changes in the plant community over a period of 30 years following restoration using trampling protection and marram grass (Ammophila arenaria) planting in four sites that were highly degraded by sand extraction and over‐frequentation. We used several indicator types (geomorphological, taxonomic, functional) at different spatial scales (alpha, beta, gamma) to assess recovery since restoration in four sites of the northern coast of Brittany and undertook comparison with reference sites. Results: Our results indicate that over the 30 years after restoration the gamma richness of typical species and overall vegetation conservation status increased. We also found that restoration induces the recovery of zonation in plant communities, which become organized along the typical sea–inland gradient. We showed that use of functional traits and diversity indices is effective to compare restored communities with reference data from the literature. Based on this approach, we demonstrated that, according to most functional indicators, restored communities converge over time with the patterns found in reference data. Conclusions: We demonstrated that restoration of coastal dunes after 30 years induced the recovery of sand accumulation, typical species cover, sea–inland plant community zonation and community functional characteristics. Despite these positive results, which indicated overall success and confirmed interest in such restoration projects, we found an important discrepancy in restoration success among study sites (e.g., level of recovery of typical species cover, functional diversity). Finally, our study confirms the interest of functional composition and functional diversity as restoration success metrics.We demonstrated that 30 years of coastal dune restoration induced recovery of sand accumulation, target species, sea–inland plant community zonation and community functional characteristics. Our study finally confirms the use of functional composition and functional diversity as restoration success metrics. [ABSTRACT FROM AUTHOR]

Questions: The adjustment of grazing pressure affects above‐ground biomass and its variation in space and time, which is a tool in grassland management for biodiversity conservation and livestock production. Here we ask to what extent the variation in above‐ground biomass at the scale of quadrats is predictive of (1) community‐weighted means (CWMs) of leaf traits and functional groups, and (2) functional diversity in grasslands. Location: Native grasslands (Campos) of northeastern Uruguay. Methods: Four paddocks of a replicated, randomized experiment, managed under high and low grazing pressure for 10 years, were monitored for above‐ground biomass and species composition during autumn, winter and spring of 2017 using 20 cm × 20 cm permanent quadrats. Thirteen dominant species were assessed seasonally for leaf dry matter content (LDMC), specific leaf area (SLA), leaf tensile strength (LTS), and leaf width (LW), which were used in cluster analysis to define functional groups. We computed CWMs and functional diversity at the quadrat scale, which we related to the above‐ground biomass by using linear mixed models attached to a maximum permutation test. Results: We identified four functional groups (FGs A, B, C and D), which considered the phenological seasonality of species and thus the highly intra‐functional group variability of leaf traits across seasons. Lower levels of biomass increased the dominance of species with lower LDMC and wider leaves (FG A and B), while higher levels of biomass increased species with higher LDMC and narrower leaves (FG D, represented by Nassella charruana), and increased the functional diversity. Conclusions: Fine‐scale variation of above‐ground biomass is predictive of functional composition and diversity in grazed grasslands. Grazing management practices that create and maintain spatiotemporal heterogeneity can be used to favor the conservation of biodiversity and the functionality of native grasslands.Fine‐scale biomass predicts diversity. [ABSTRACT FROM AUTHOR]

Aims: Elevational patterns of plant species richness may be caused by multiple underlying mechanisms, and the same pattern can be predicted by different mechanisms. Using the steep elevational gradient of Tenerife as a model system, we aimed to test if the application of a trait‐based approach can help disentangle the role of potential mechanisms behind local elevational plant species richness patterns. Location: Tenerife, Canary Islands, Spain. Methods: Based on vegetation relevés from natural vegetation and disturbed roadside habitat, along an elevational gradient of 2300 m, we observed a peak of plant species richness in the lowest third of the gradient. We considered three mechanisms potentially shaping this pattern: environmental filtering (temperature and precipitation), effects of area and disturbance. For these mechanisms, we hypothesized a distinct pattern of functional trait–elevation relationships. These were tested with in‐situ data of nine functional leaf traits, from which we calculated community‐weighted means (CWM) of traits and functional diversity (Rao's Q). Results: While species richness was significantly positively correlated with temperature, area and disturbance, filtering through temperature was the only mechanism for which we could confirm most of our mechanism‐specific hypotheses about elevational trait changes: with increasing elevation, CWMs of most traits indicated shifts from acquisitive to conservative growth strategies, and functional diversity decreased. The shift of growth strategies also supported the disturbance effect, as we found overall more acquisitive communities at roadsides compared to natural habitats. Conclusions: Our results indicate that simple correlations between species richness and abiotic variables are not necessarily causal. Additional testing of mechanism‐specific hypotheses for elevational patterns of both CWMs and functional diversity can help distinguishing between correlational and mechanistic relationships between species richness and environmental variables. The trait‐based framework presented here can be fruitfully applied to better understand species richness patterns in other regions and across other types of environmental gradients. [ABSTRACT FROM AUTHOR]

The functional composition of plant communities (FCPC) makes a significant contribution to ecosystem properties, functions, and services. Here, we used 18 plant functional traits from the sPlot database v2.1 and the global forest management type dataset to explore the links between forest management and the FCPC. We used the post hoc Tukey test to explore the differences in the community-weighted mean (CWM) and community-weighted variance (CWV) among different forest management types [i.e., intact forests, managed forests with natural regeneration, planted forests, plantation forests (with up to a 15-year rotation), and agroforestry]. We found that different forest management types can result in significant variability in plant communities’ functional composition. Plantation forests could result in significantly higher CWM and CWV compared to intact forests, and significant differences could occur between natural and managed forests with natural regeneration. Furthermore, the relationship between forest management practices and the FCPC depends on ecozone type changes. There were significant differences between natural and plantation forests for CWM and CWV in temperate forests. Our study provides an effective reference for applying plant functional traits to regulate and optimize the functions and services of forest ecosystems.

Plant functional traits have received increasing attention at a community scale. There are three methods, for scaling‐up from the organ to the community: species arithmetic mean (SAM), community‐weighted mean (CWM), and per unit land area community‐weighted mean (PLA‐CWM). To date, it is unclear how these scaling‐up methods influence the spatial variation of these plant community traits. Here, we consistently measured the leaf nitrogen content (N) of 1,844 plant species from 22 natural communities along a 5,100 km transect with a temperature and precipitation gradient and explored the potential effect of different scaling‐up methods on leaf N in the community as NSAM, NCWM, and NPLA‐CWM. Our results demonstrated that leaf N at the community scale showed a different spatial variation among the three methods and was dependent on climate or plant community types. NSAM and NCWM decreased significantly with the increasing of mean annual precipitation (MAP), and NPLA‐CWM showed the opposite trend. Furthermore, NSAM overestimated the leaf nitrogen content at the community level compared to NCWM. SAM underestimated leaf nitrogen in a dry or cold environment and vice versa in a wet or warm environment compared to CWM. With MAP greater than 300 mm or with mean annual temperature higher than 0.24°C, NSAM and NCWM were significantly different, which should be emphasized. Based on these findings, over‐ or underestimation from different scaling‐up methods should be tested in other plant community traits. In summary, community‐weighted methods (CWM and PLA‐CWM), covering community information on species composition and traits, implicating many important ecological processes, should be helpful for evaluating the spatial variation of plant community traits on a large scale in the future. Plain Language Summary: Different methods often lead to different results for one thing. Therefore, we use three methods: species arithmetic mean (SAM), community‐weighted mean (CWM), and per unit land area community‐weighted mean for scaling‐up plant functional traits from organ to community. We choose leaf nitrogen content (N), one of the most important plant traits, for our study. A total of 26 natural communities along 5,000 km transect were used in this study. Usually, large‐scale studies may be more convincing. Our results showed that there were different spatial variations among three methods and different relationships with environmental factors. Moreover, we found that under certain environment (mean annual precipitation >300 mm and mean annual temperature >0.24°C), SAM overestimates leaf N at a community scale. We suggest that community weighting methods (CWM and PLA‐CWM), which cover species composition traits and uniform units of community information, implicate many important ecological processes and should be useful for assessing spatial variation in plant community traits at large scales. Key Points: Plant community traits are used to study ecosystem properties, but the influence of scaling‐up methods is unclearThree calculated methods were evaluated for leaf nitrogen content at a community scaleLeaf nitrogen content at the community scale by the community‐weighted mean should be promising since they are more realistic [ABSTRACT FROM AUTHOR]

Large trees are key components of forest communities and can influence several ecosystem processes. Moreover, in the savannas where mainly light is not a limiting factor in plant growth, the effects of large trees in plant community as facilitators or promoting local competition are still unclear. For the purpose of the study, 9 plots of 100 m2 were demarcated in a savanna woodland situated in a conservation unit and without fire register in Brazil. Plots were delimited surrounding large trees with different size diameter and all the structural and functional traits were measured in the surrounding community. A total of 395 plants were sampled and recorded in 73 species and 32 botanical families. The study found that large trees were associated with higher litter deposition and the dominance of forest species with shallow crowns, higher wood density and leaf nitrogen content and lower specific leaf area. These results indicated that large trees could facilitate shade-tolerant species in increasing competition for light with shade-intolerant species. Therefore, large trees could contribute to forest tree species conservation in savanna environments, allowing the coexistence of forest and savanna species at local scale. [ABSTRACT FROM AUTHOR]

Coastal wetlands are among the most carbon-rich ecosystems in the world. Litter decomposition is a major process controlling soil carbon input. Non-additive effect of litter mixture on decomposition has been observed in many terrestrial plants but rarely tested in coastal species. We selected three common mangrove species and one saltmarsh species co-occurring in subtropical coasts to test whether the non-additive effect occurs when their litters mixed together, and how the nutrients release into water are impacted consequently. A litter-bag experiment was carried out in a glasshouse with single and mixed leaf litters. Non-additive effects were observed in the litter mixtures of mangrove species Aegiceras corniculatum vs. Kandelia obovata (antagonistic) and A. corniculatum vs. Avicennia marina (synergistic), but not in the litter mixtures of A. corniculatum (mangrove species) vs. Spartina alterniflora (saltmarsh species). The strength of the non-additive effect was unrelated to the initial trait dissimilarity of litters. Instead, the decomposition rate and mass remaining of litter mixtures were strongly related to the carbon concentrations in litter mixtures. Nutrient content in waters was dependent on the decomposition rate of litter mixtures but not on the initial nutrient concentrations in litters. Despite the behind mechanisms were not yet revealed by the current study, our findings have improved the understanding of the litter decomposition of coastal species and the consequent nutrient release. [ABSTRACT FROM AUTHOR]

Abstract Background Regarding the most important ecological challenges, scientists are increasingly debating the relationship between biodiversity and ecosystem function. Despite this, several experimental and theoretical researches have shown inconsistencies in biodiversity and ecosystem function relationships, supporting either the niche complementarity or selection effect hypothesis. The relationship between species diversity, functional diversity, and aboveground biomass carbon was investigated in this study employing standing aboveground carbon (AGC) stock as a proxy measure for ecosystem function. We hypothesized that (i) effects of diversity on AGC can be transmitted through functional diversity and functional dominance; (ii) effects of diversity on AGC would be greater for functional dominance than functional diversity; and (iii) effects of functional diversity and functional dominance on carbon stock varied with metrics and functional traits. Community-weighted means (CWM) of functional traits (wood density, specific leaf area, and maximum plant height) were calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multi-trait functional diversity (selection effects) indices were computed. We tested the first hypothesis using structural equation modeling. For the second hypothesis, the effects of environmental variables such as slope, aspect, and elevation were tested first, and separate linear mixed-effects models were fitted afterward for functional diversity, functional dominance, and the two together. Results Results revealed that slope had a significant effect on aboveground carbon storage. Functional diversity and functional dominance were significant predictors of the aboveground carbon storage (22.4%) in the dry evergreen Afromontane forest. The effects of species richness on aboveground carbon storage were mediated by functional diversity and functional dominance of species. This shows that both the selection effects and the niche complementarity are important for aboveground carbon storage prediction. However, the functional diversity effects (niche complementarity) were greater than functional dominance effects (selection effects). Conclusions Linking diversity and biodiversity components to aboveground carbon provides better insights into the mechanisms that explain variation in aboveground carbon storage in natural forests, which may help improve the prediction of ecosystem functions.

Although an increasing amount of attention is being paid to how human activities alter plant communities, little is known about the consequences of these changes on species’ assemblages and biodiversity patterns. Using three forest types (a Pinus yunnanensis man-made forest; Eucalyptus smithii man-made forest; and natural secondary forest) in mid-Yunnan, China, we investigated the distribution patterns of species and traits and analyzed diversity patterns and relationships, including those between species diversity, functional diversity, and soil microbial diversity. We found that species co-occurrence patterns in the Pinus yunnanensis man-made forest and natural secondary forest were non-random. The specific leaf area in the Eucalyptus smithii man-made forest and leaf nitrogen concentration in the Pinus yunnanensis man-made forest were both over-dispersed according to the mean Euclidean neighbor distance in the trait space. The natural secondary forest had higher values of species diversity, functional diversity, community-weighted means, and soil microbial diversity than the man-made forest types did. An overall low covariation between species diversity and community-weighted means suggested that the coexistence of many species does not necessarily support functional differentiation among these species. Variance partitioning revealed that soil microbial diversity was mainly regulated by community-weighted means. In conclusion, our results suggest that the naturally recovering forest was better than man-made plantations based on biodiversity patterns.

Functional characteristics are increasingly used to evaluate the success of different vegetation restoration. Community functional diversity (FD) and the community-weighted mean (CWM), as two main complementary components, are closely linked to site environment and ecosystem functions. However, the patterns and driving factors of functional characteristics are still not clear in different vegetation restoration types. Here, four community restoration types (secondary shrubland, SL; Pinus yunnanensis forest, PF; mixed needle–broad-leaved forest, MF; natural secondary forest, NSF) were selected to investigate species diversity, FD, CWM, and soil physicochemical properties. The relative effects of species diversity and soil abiotic features on variation in functional characteristics were then evaluated. We found that different restoration communities altered most community structures and functional properties in terms of species diversity, FD, and CWM. CWM values and FD in different communities presented different distribution patterns depending on certain traits and parameters. Significant correlations between functional traits were found at the species and community scales, suggesting a potential covariation between these selected traits in communities. The results of redundancy analysis and variation partitioning showed that most of the variation in functional characteristics, especially CWM, was explained by soil moisture and available phosphorus, indicating that habitat filters regulate the functional characteristics of plant communities mainly by changing the dominant species composition and functional traits of species. Therefore, the selection of restoration species adapted to low soil moisture and available phosphorus and the construction of communities based on selected species as the dominant species can effectively drive community assembly and ecosystem functions in the vegetation restoration process.

Determining how climate affects biotic interactions can improve understanding of drivers of context‐dependence and inform predictions of how interactions may influence plants under future climates. In arid environments, the community‐level impacts of seed predators may depend strongly on aridity; yet, long‐term studies documenting impacts of granivores on plant communities over variable climate conditions remain scarce. We evaluated how rodent exclusion interacted with climate to influence grassland and shrubland forb communities and the community‐scale distribution of seed mass over 15 years in the climatically variable northern Chihuahuan Desert. In this dynamic system, two seasonally distinct plant community phases occur annually, one in spring and the other during the summer monsoon. Rodent exclusion significantly altered the community composition of monsoon season plant communities in both grassland and shrubland, but did not affect spring plant composition. Rodents suppressed the abundance of larger‐seeded forb species and promoted smaller‐seeded species. As a consequence, rodent exclusion increased community seed mass (CWM) in monsoon forb communities, most strongly in grassland. The magnitude of impacts of rodents on seed mass varied substantially from year‐to‐year, tracking variation in climate. Specifically, rodent exclusion increased community mean seed mass the most in dry years (grassland) or in years following dry years (shrubland). Rodent exclusion had relatively weak effects on plant species diversity and richness. Our results indicate that climate interacts with the presence of rodents to structure not only the composition but also the traits of desert plant communities. [ABSTRACT FROM AUTHOR]

Altered microclimatic conditions and higher disturbance at forest edges create environmental stress and modify resource gradients from edge to interior, changing the selection pressures acting on individuals. Although community‐weighted trait‐mean (CWM) shifts along edge gradients have been widely documented at the species level, it is unclear how edge effects act at the individual level, and whether the direction of intraspecific trait shifts mirrors that of CWM shifts in response to edge effects. On 20 islands in the Thousand Island Lake, China, we established 484 plots (2 × 2 m) in a stratified random design across distances of 0–128 m from the forest edge. Within each plot, we sampled leaves (n = 34 768) from within and among all 2993 individuals of 68 species and measured five leaf traits (leaf area, LA; specific leaf area, SLA; leaf dry matter content, LDMC; thickness, LT; chlorophyll content, LCC). Using generalized linear mixed models, we found that different leaf traits exhibited contrasting shifts in inter‐ versus intraspecific trait variation in response to edge effects. For SLA, LT and LCC, negative covariance between inter‐ and intraspecific trait shifts resulted in dampening of community‐wide trends compared to CWM response to edge effects. In contrast, the community‐wide trend for LDMC was reinforced due to positive covariance between inter‐ and intraspecific trait shifts, while for LA the direction of covariance shifted from negative to positive on small versus large islands. Together, edge effects alter selection regimes in reassembling plant communities. Predicting the community‐wide consequences depends on the degree to which there is negative versus positive covariance between species sorting and within‐species adaptation. The widely‐used CWM approach can mask contrasting trait selection pressures acting on individuals within local populations. Individual‐level trait variation can improve understanding of community re‐assembly trajectories in response to global environmental change. [ABSTRACT FROM AUTHOR]

Turnover in species composition and the dominant functional strategies in plant communities across environmental gradients is a common pattern across biomes, and is often assumed to reflect shifts in trait optima. However, the extent to which community‐wide trait turnover patterns reflect changes in how plant traits affect the vital rates that ultimately determine fitness remain unclear.We tested whether shifts in the community‐weighted means of four key functional traits across an environmental gradient in a southern California grassland reflect variation in how these traits affect species' germination and fecundity across the landscape.We asked whether models that included trait–environment interactions help explain variation in two key vital rates (germination rates and fecundity), as well as an integrative measure of fitness incorporating both vital rates (the product of germination rate and fecundity). To do so, we planted seeds of 17 annual plant species at 16 sites in cleared patches with no competitors, and quantified the lifetime seed production of 1360 individuals. We also measured community composition and a variety of abiotic variables across the same sites. This allowed us to evaluate whether observed shifts in community‐weighted mean traits matched the direction of any trait–environment interactions detected in the plant performance experiment.We found that commonly measured plant functional traits do help explain variation in species responses to the environment—for example, high‐SLA species had a demographic advantage (higher germination rates and fecundity) in sites with high soil Ca:Mg levels, while low‐SLA species had an advantage in low Ca:Mg soils. We also found that shifts in community‐weighted mean traits often reflect the direction of these trait–environment interactions, though not all trait–environment relationships at the community level reflect changes in optimal trait values across these gradients.Synthesis. Our results show how shifts in trait–fitness relationships can give rise to turnover in plant phenotypes across environmental gradients, a fundamental pattern in ecology. We highlight the value of plant functional traits in predicting species responses to environmental variation, and emphasise the need for more widespread study of trait–performance relationships to improve predictions of community responses to global change. [ABSTRACT FROM AUTHOR]

Ecological selection is a major driver of community assembly. Selection is classified as stabilizing when species with intermediate trait values gain the highest reproductive success, whereas selection is considered directional when fitness is highest for species with extreme trait values. Previous studies have investigated the effects of different selection types on trait distribution, but the effects of selection on species diversity have remained unclear. Here, we propose a framework for inferring the type and strength of selection by studying species diversity and trait distribution together against null expectations. We use a simulation model to confirm our prediction that directional selection should lead to lower species diversity than stabilizing selection despite a similar effect on trait community‐weighted variance. We apply the framework to a mesocosm system of annual plants to test whether differences in species diversity between two habitats that vary in productivity are related to differences in selection on seed mass. We show that, in both habitats, species diversity was lower than the null expectation, but that species diversity was lower in the more productive habitat. We attribute this difference to strong directional selection for large‐seeded species in the productive habitat as indicated by trait community‐weighted mean being higher and community‐weighted variance being lower than the null expectations. In the less productive habitat, we found that community‐weighted variance was higher than expected by chance, suggesting that seed mass could be a driver of niche partitioning under such conditions. Altogether, our results suggest that viewing species diversity and trait distribution as interrelated patterns driven by the same process, ecological selection, is helpful in understanding community assembly. [ABSTRACT FROM AUTHOR]

The mass ratio hypothesis (functional dominance) and niche complementarity hypothesis (functional diversity) are two potential approaches for making the link between biodiversity and biomass. It is yet unclear how biodiversity and biomass are related in seasonally dry tropical forest (SDTF) communities where there is a seasonal water limitation. The objective of this study was to quantify the effects of environmental filtering on ecosystem functioning, especially those related to biodiversity and above-ground biomass. We estimated biomass and functional traits for all species in five plots at five sites in a SDTF. We related functional diversity and community-weighted trait mean (CWM) values to above-ground biomass (AGB) using linear mixed models. Functional diversity was not related to AGB, while CWM values of vessel density (VD) were positively and the Carlquist Vulnerability Index (CVI) was negatively related to AGB. The CWM values of functional traits related to the trade-off between safety of water transport and the efficiency of water conductivity and conservative strategies (VD and CVI) were good predictors of AGB. The mass ratio hypothesis appears to be a better predictor of AGB than niche complementarity in our study conducted in the SDTF. [ABSTRACT FROM AUTHOR]

Human activities markedly modify diversity patterns of plant communities and their response to environmental conditions, with subsequent consequences for ecosystem functions. We measured 11 key functional traits of 47 plant species and assessed both taxonomic and functional composition as well as above‐ground biomass (AGB) of plant communities from 127 plots in the Lake Dongting wetland. Using a generalized multilevel path model, we examined the cascading effects of hydrological gradients on plant diversity and ecosystem functions in two distinct habitat types (short grassland with a natural community dominated by Carex spp. and tall grassland with a managed artificial community dominated by Triarrhena lutarioriparia and Phragmites australis). We found significant differences in the response of plant diversity and AGB to hydrological gradients. Species richness, Shannon–Wiener diversity, multiple‐trait functional diversity measures (i.e., functional richness, functional dispersion & Rao's quadratic entropy) and community‐weighted mean (CWM) of shoot height were all significantly higher and functional divergence and CWM of tuber significantly lower in tall grassland. AGB was significantly higher in short grassland, largely driven by variations of functional diversity rather than of taxonomic diversity. Moreover, we found a significant cascading effect of elevation and soil moisture on AGB, directly or indirectly induced by changes in functional diversity in the short grassland, while only direct effects of elevation on AGB were observed in the tall grassland. Therefore, our study provides strong evidence that human‐induced changes in habitat types uncoupled the cascading effects of hydrological gradients on ecosystem functions mediated by either the taxonomic or the functional diversity. [ABSTRACT FROM AUTHOR]

Coastal dunes are characterised by strong interactions between biotic and abiotic factors along a short gradient from the shoreline to the inland region. We carried out an ecological analysis of the vegetation in a protected area of the Italian coast to evaluate the relationships among species abundance, the occurrence of morphoanatomical traits related to leaves, stems, and roots, and soil variables. Three transects were established perpendicular to the shoreline, with 27 plots distributed in the frontal dunes, backdunes, and temporarily wet dune slacks. An analysis based on community-weighted mean values showed that the pioneer communities of the frontal dunes were dominated by ruderals that are well adapted to the harsh ecological conditions of these environments, showing succulent leaves, high limb thickness values, and low values for leaf dry matter content (LDMC). The backdune vegetation was a mosaic of annual herbaceous and perennial shrub communities showing both ruderal and stress-tolerant strategies (clonality, sclerified leaves, high LDMC values, root phenolics) consistent with less extreme ecological conditions. The dune slack areas were dominated by plants showing adaptations to both arid and flooded environments, such as C4 photosynthesis, amphistomatic leaves, and abundant aerenchyma in the roots. The invasive status, C4 photosynthesis, leaf trichomes, and aerenchyma in the roots were significantly correlated with soil humidity, organic matter content, and pH. These results demonstrate the usefulness of anatomical traits (including root system traits) in understanding the functional strategies adopted by plants. Invasive species tended to occupy plots with high levels of soil moisture, suggesting an avoidance strategy for the harsh environmental conditions of coastal sand dunes. Finally, we suggest including information regarding root systems into coastal monitoring programs because they are directly linked to soil parameters useful in coastal dune management and protection. [ABSTRACT FROM AUTHOR]

Rapid biodiversity loss has triggered decades of research on the relationships between biodiversity and community stability. Recent studies highlighted the importance of species traits for understanding biodiversity-stability relationships. The species with high growth rates ('fast' species) are expected to be less resistant to environmental stress but recover faster if disturbed; in contrast, the species with slow growth rates ('slow' species) can be more resistant but recover more slowly if disturbed. Such a 'fast-slow' trait continuum provides a new perspective for understanding community stability, but its validity has mainly been examined in plant communities. Here, we investigate how 'fast-slow' trait composition, together with species richness and environmental factors, regulate avian community stability at a continental scale. 2. We used bird population records from the North American Breeding Bird Survey during 1988-2017 and defined avian community stability as the temporal invariability of total community biomass. We calculated species richness and the community-weighted mean (CWM) and functional diversity (FD) of four key life-history traits, including body size, nestling period (i.e. period of egg incubation and young bird fledging), life span and clutch size (i.e. annual total number of eggs). Environmental factors included temperature, precipitation and leaf area index (LAI). 3. Our analyses showed that avian community stability was mainly driven by the CWM of the 'fast-slow' trait. Communities dominated by 'fast' species (i.e. species with small body size, short nestling period and life span and large clutch size) were more stable than those dominated by 'slow' species (i.e. species with large body size, long nestling period and life span and small clutch size). Species richness and the FD of the 'fast-slow' trait explained much smaller proportions of variation in avian community stability. Temperature had direct positive effects on avian community stability, while precipitation and leaf area index affected community stability indirectly by influencing species richness and trait composition. 4. Our study demonstrates that composition of 'fast-slow' traits is the major biotic driver of avian community stability over North America. Temperature is the most important abiotic factor, but its effect is weaker than that of the 'fast-slow' trait. An integrated framework combining 'fast-slow' trait composition and temperature is needed to understand the response of avian communities in a changing environment. [ABSTRACT FROM AUTHOR]

Ellenberg indicator values (EIVs) express plant preferences for temperature, light, continentality, soil moisture, pH, and soil nutrients, and have been largely used to deduce environmental characteristics from plant communities. However, EIVs might also be used to investigate the importance of filtering mechanisms in shaping plant communities according to species ecological preferences, a so far overlooked use of EIVs. In this paper, we investigated how community-weighted means (CWM), calculated with EIVs, varied along an elevational gradient in a small mountain in Central Italy. We also tested if species abundances varied according to their ecological preferences. We found that the prevalence of thermophilous species declines with elevation, being progressively replaced by cold-adapted species. Heliophilous species prevail at low and high elevations (characterized by the presence of open habitats), whereas in the middle of the gradient (occupied by the beech forest), sciophilous species predominate. Variations for moisture and soil nutrient preferences followed a similar pattern, probably because of the high moisture and nutrient levels of forest soils with a lot of humus. No distinct pattern was detected for EIVs for pH and continentality since these factors are subject to more local variations. These results highlight the possible role of EIVs to investigate how environmental gradients shape plant communities.