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Ecological processes such as environmental filtering and biotic interactions that shape species' traits and community diversity often vary with geographic distance, potentially generating spatial structures in trait variation, covariation and biodiversity data. Understanding spatial structures of trait, environment and biodiversity, or the spatial link between those factors, is fundamental to identifying spatially explicit assembly processes or biodiversity distributions in spatially heterogeneous landscapes but remains unclear.To address the issue, we gathered individual‐level leaf and diameter traits data paired with environmental data from a 4.8 ha subtropical Chinese forest and divided the forest into 25, 100, 400 and 1936 m2 grids representing contrasting spatial grains. Using Moran's correlograms, we quantified the spatial structures of trait variation and covariation, environmental conditions and biodiversity. We assessed the links between those variables using path analyses.Most variables were spatially positively autocorrelated. However, trait mean was more autocorrelated than trait variation or covariation, and intraspecific trait variation was more autocorrelated than interspecific variation. Autocorrelations in those community properties were generally weak at the large grain.Path analyses indicated positive associations between interspecific trait variation and species diversity at a very small to medium scale and a positive association between intraspecific variation and small‐scale functional diversity. Trait covariation constrained biodiversity, and multi‐trait means were negatively linked to very small‐ to medium‐scale species diversity but positively to medium‐ and large‐scale functional diversity. Patterns regarding multi‐trait community structure–environment–biodiversity associations were generally held for individual traits. However, depending on the trait, spatial scale and plant ontogenic stage, the pattern's strength changed, or occasionally, their sign reversed.We attribute spatial patterns in multi‐trait mean and covariation to scale‐dependent variation in environmental heterogeneity and trait variation to scale‐dependent competition.Synthesis. Our study provides novel insights into spatial and scale‐dependent variability in functional community structure, environment and biodiversity, and their relationships. Our results demonstrate the usefulness of spatial trait analyses in identifying scale‐dependent assembly processes or finding the importance of processes to biodiversity distributions in spatially heterogeneous landscapes. A spatially explicit perspective is thus helpful for the progress of trait ecology. [ABSTRACT FROM AUTHOR]

Understanding how plant individuals perform in non‐local sites is key in the context of contemporary range shifts along elevation. Transplant experiments conducted in mountain ecosystems are rising as key tools to measure the intraspecific response of individuals transplanted across contrasting elevations. However, a synthesis quantifying patterns of plant performance in response to changes in abiotic factors across different species and mountain ranges is still lacking.We conducted a meta‐analysis to quantitatively summarize patterns of plant species' performance variation in response to changes in temperature and precipitation within their elevation range across multiple transplant experiment studies. We compiled a dataset obtained from 38 studies and 49 vascular plant species in total addressing intraspecific performance variation in terms of survival, germination, biomass, height, number of vegetative organs, number of reproductive units, SLA and leaf size. We both compared pairs of transplanted individuals to those growing at their site of origin ('away vs. home') and to the local individuals found at the site of transplant ('foreign vs. local').Overall, individuals transplanted downward showed larger biomass and height compared to their site of origin but failed to adjust these traits and survival to that of local individuals. Individuals transplanted upward adjusted their traits by decreasing plant growth and number of reproductive units to that of local individuals but showed lower survival. Importantly, changes in survival, biomass, height, leaf size, number of vegetative organs and reproductive units increased linearly with the difference in mean annual temperature between site of transplant and site of origin in the 'away vs. home' comparison. Conversely, changes in biomass, leaf size, number of vegetative organs and reproductive units increased with mean annual precipitation difference between sites in the 'foreign vs. local' comparison.Synthesis. We detected common trends in survival and intraspecific trait variation across different species and transplant experiments conducted along elevational gradients. Because plasticity and adaptation play a crucial role in plant shift, establishment and persistence under non‐local environmental conditions, our meta‐analysis contributes to better understand how rapid plant shifts are constrained by climatic conditions within species' elevational range. [ABSTRACT FROM AUTHOR]

Between‐species variation in nutrient resorption is one of the mechanisms explaining the positive relationship between biodiversity and primary productivity. Yet, the role of within‐species variations in nutrient resorption in mediating the relationship between biodiversity and productivity remains unclear.We examined how within‐species nutrient resorption, and ultimately productivity, respond to changes in species richness by using four traits related to nitrogen and phosphorus use in four dominant species from different plant functional groups in a biodiversity removal experiment in the temperate steppe.Nitrogen and phosphorus concentrations in both green and senesced leaves in all species significantly decreased with increasing plant species richness, suggesting that plants used those limiting nutrients more efficiently with increasing biodiversity. Plants in higher diversity communities resorbed more nutrients during senescence, which may facilitate reproduction and vegetative regrowth in the next year.Synthesis. Our results highlight the importance of considering within‐species variation in nutrient resorption as an important underlying mechanism explaining the positive effects of biodiversity on primary productivity and ecosystem carbon accumulation. [ABSTRACT FROM AUTHOR]

A central issue of community ecology is finding rules that explain the composition and abundance of coexisting species. Nowadays two main processes, environmental filtering and limiting similarity, are thought to play the main roles in structuring communities. Their relative importance under different environmental conditions, however, is still not properly clarified., We studied the strength and the effect of environmental filtering (causing convergence) and limiting similarity (causing divergence) in 137 sample plots along an extremely long environmental gradient ranging from open sand grasslands to highly productive marshes, using a trait-based approach. The main environmental gradient (i.e. productivity) was characterized by the Normalized Difference Vegetation Index, an indicator of above-ground live biomass. Cover of the plant species was estimated visually. Values of 11 plant traits were collected from field measurements and data bases. Mean and dispersion of the trait values of the plots were quantified by community-weighted means and Rao's quadratic entropy. Trait convergence and divergence were tested by randomization tests, followed by the study of changes in effect size along the productivity gradient by fitting generalized additive mixed models ( GAMM)., For vegetative traits we found mainly convergence, indicating the filtering effect of environmental constraints, while traits related to regeneration showed divergence., The strength of convergence in vegetative traits generally decreased as productivity grew, indicating that while under harsh conditions environmental constraints strongly limit the possible trait values, under more benign conditions various water and nutrient use strategies are adaptable. At high productivity, the strength of divergence in regenerative traits decreased. Since the larger diversity of vegetative traits found here reduces competition, the importance of diverse reproductive strategy is probably lower., Synthesis. Our results partly support the stress-dominance hypothesis, but reveal that assembly rules are more complex. The relative importance of environmental filtering and limiting similarity depends on the trait and on the environmental conditions of the habitat. Traits related to resource use are generally limited by environmental filtering, and this restriction is weakening as conditions become more favourable, while traits related to regeneration are constrained by limiting similarity and are more diverse under harsh conditions. [ABSTRACT FROM AUTHOR]

Resprouting of woody species after above-ground damage may help plants to persist longer at a given site and quickly reoccupy disturbed sites, thereby strongly influencing forest dynamics. Resprouting has been discussed from two adaptation perspectives: recovery from damage by catastrophic disturbance and survival in frequently disturbed shaded understorey. However, few studies have comprehensively dealt with both adaptation types to understand resprouting strategies., To understand the adaptive significance of resprouting, we assessed the size dependence of resprouting ability after stem clipping for 24 deciduous broad-leaved species, including shrubs, sub-canopy and canopy trees, in a cool-temperate forest in Japan. The community assembly includes species adapted to past catastrophic disturbances (e.g. fire, logging) and to stable forest with intermittent treefall (currently the dominant disturbance). We correlated resprouting ability with life-history strategies based on demographic parameters and plant functional traits, such as leaf mass per area ( LMA), leaf toughness and wood density., All the studied species could resprout in juveniles, and resprouting ability increased as stump size increased. Most sub-canopy and canopy trees lost their ability to resprout after attaining a particular stump size, whereas shrub species retained the ability to resprout throughout their lifetimes., The relative growth rate, LMA and foliar nitrogen did not greatly influence the resprouting ability of a species. In contrast, species with smaller maximum size, lower leaf toughness and lower wood density had better juvenile resprouting ability. This better resprouting ability may have evolved because these characteristics make them more vulnerable to shaded understorey. However, species with larger maximum size and lower leaf toughness retained their ability to resprout to a larger size., Synthesis. A better resprouting ability is related to the ability to survive frequent disturbances, in juveniles, which are characteristics of both forest understorey and frequent fire or drought. To retain resprouting ability until grown seems to be an adaptation to survive infrequent large disturbances. Light-demanding species, which generally have better resprouting ability than shade-tolerants both in juveniles and adults, are adapted to disturbances of various scale and frequency; however, shade-tolerants could survive well in the understorey due to a combination of stronger physical defences and resprouting ability. [ABSTRACT FROM AUTHOR]

Habitat filtering ( HF, trait convergence) and niche differentiation ( ND, trait divergence) are known to impact upon plant community structure. Both processes integrate individual responses to the abiotic environment and biotic interactions. Thus, it is difficult to clearly identify the underlying abiotic and biotic factors that ultimately impact community structure by looking at community-level patterns of trait divergence or convergence alone., We used a functional trait-based and multiscale approach to assess how biotic interactions and aridity determine the functional structure of semi-arid shrublands sampled along a large aridity gradient in Spain. At the regional scale, we investigated functional differences among species (axes of specialization) to identify important traits for community assembly. At the community scale, we evaluated the relative impact of HF and ND on community structure using a null model approach. Finally, at the plant neighbourhood scale, we evaluated the impact of biotic interactions on community structure by investigating the spatial patterns of trait aggregation., The shrub species surveyed can be separated along four axes of specialization based on their above-ground architecture and leaf morphology. Our community scale analysis suggested that the functional structure of semi-arid communities was clearly non-random, HF and ND acting independently on different traits to determine community structure along the aridity gradient. At the plant neighbourhood scale, the spatial distribution of species was also clearly not random, suggesting that competition and facilitation impacted on the observed changes in the functional diversity of shrubland communities along the aridity gradient., Synthesis: Our results demonstrated that HF and ND acted simultaneously on independent traits to jointly determine community structure. Most importantly, our multiscale approach suggested that competition and facilitation interplayed with aridity to determine this structure. Competition appeared to be constant along the aridity gradient and explained the high functional diversity observed in semi-arid shrublands. Facilitation affected subordinate and rare species and, thus, may act to enhance the biodiversity of these ecosystems. Finally, the framework employed in our study allows moving forward from the examination of patterns to the development of mechanistic trait-based approaches to study plant community assembly. [ABSTRACT FROM AUTHOR]

In fire-prone ecosystems, bark protects the stem bud bank from fire. Absolute bark thickness is a good indicator of this protective function, but it depends on stem size as well as inherent differences between species. Relative bark thickness (i.e. relative to stem diameter) takes the latter into account. We argue that relative bark thickness is an important functional trait offering insights to the evolution of species persistence in fire-prone habitats., During growth ontogeny different species can acquire absolutely thick bark through having: (i) relatively thick bark (i.e. an early commitment to thick bark) or (ii) relatively thin bark but fast stem diameter growth rates. We test the hypothesis that the most effective way of protecting tree stems from frequent fire is by having relatively thick-barked small stems. We predict that species with higher relative bark thickness are more common in fire-prone habitats. In habitats with long fire-free intervals such as rainforest, delayed investment in bark thickness results in thin bark., We examined the relative bark thickness of woody congeners from Australian non-fire-prone forest and fire-prone savanna and in other tree-dominated systems world-wide. We determined the relative cost of acquiring absolute bark thickness of 0.5 cm for different rates of bark allocation. The insulating benefits of bark were considered a linear function of bark thickness., Synthesis. We suggest that relatively thick bark minimizes the costs of acquiring absolutely thick bark, and it confers greater protection to smaller stems. The cost of acquiring thick bark prevents small trees from merely accumulating bark as a consequence of fast height or stem diameter growth. Accordingly, our field survey indicated that forest species had relatively thin bark and acquired thick bark only as a consequence of very large size, while fire-prone savanna species had relatively thick-barked small stems. Based on this, relative bark thickness appears to be a good predictor of local fire regimes and is a useful plant functional trait. [ABSTRACT FROM AUTHOR]

1. Trait-based approaches applied to community ecology have led to a considerable advance in understanding the effect of environmental filters on species assembly. Although plant traits are known to vary both between and within species, little is known about the role of intraspecific trait variability in the non-random assembly mechanisms controlling the coexistence of species, including habitat filtering and niche differentiation. 2. We investigate the role of intraspecific variability in three key functional traits – specific leaf area (SLA), leaf dry matter content (LDMC) and height – in structuring grassland communities distributed along a flooding gradient. We quantified the contribution of intraspecific variability relative to interspecific differences in the trait–gradient relationship, and we used a null model approach to detect patterns of habitat filtering and niche differentiation, with and without intraspecific variability. 3. Community mean SLA and height varied significantly along the flooding gradient and intraspecific variability accounted for 44% and 32%, respectively, of these trait–gradient relationships. LDMC did not vary along the gradient, with and without accounting for intraspecific variability. Our null model approach revealed significant patterns of habitat filtering and niche differentiation for SLA and height, but not for LDMC. More strikingly, considering intraspecific trait variability greatly increased the detection of habitat filtering and was necessary to detect niche differentiation processes. 4. Synthesis. Our study provides evidence for a strong role of intraspecific trait variability in community assembly. Our findings suggest that intraspecific trait variability promotes species coexistence, by enabling species to pass through both abiotic and biotic filters. We argue that community ecology would benefit from more attention to intraspecific variability. [ABSTRACT FROM AUTHOR]