Optimal Community Assembly Related to Leaf Economic- Hydraulic-Anatomical Traits

Abstract

Multi-dimensional trait mechanisms underlying community assembly at regional scales are largely unclear. In this study, we measured leaf economic, hydraulic and anatomical traits of 394 tree species from tropical to cold temperate forests, from which we calculated the leaf trait moments (mean, variance, skewness, and kurtosis) using community-weighted methods. Economic and hydraulic traits were decoupled at the species level, but coupled at the community level, and relationships between leaf traits in observed communities were stronger than that in null communities, suggesting that the adaptive mechanisms of plant species may be different. Furthermore, leaf economic traits were distributed more evenly across species occupying communities with lower temperature and precipitation, whereas hydraulic traits were distributed more evenly under lower water availability. This suggests that limiting similarity of specific leaf traits within communities would be enhanced when related-resources are limited, and highlights the independent assembly of leaf economics and hydraulic traits in terms of functional evenness. Importantly, the moments of leaf economic and hydraulic traits of observed communities explained more variation in ecosystem productivity than that of null communities, indicating ecosystem productivity depended on traitbased community assembly. Our results highlight the principles of community assembly regarding multi-dimensionsional traits in natural forests at a regional scale.

Variation Patterns of Functional Trait Moments Along Geographical Gradients and Their Environmental Determinants in the Subtropical Evergreen Broadleaved Forests

“…Precipitation seasonality was strongly negatively correlated with the mean of wood density and leaf dry matter content, while positively correlated with the mean of leaf nutrient concentrations ( Figures 2 , 3 ). It suggested that seasonal precipitation may favor species with efficient water transport and nutrient utilization to support fast growth during the wet season ( Liu et al, 2020 ). Results also showed that soil total nitrogen and total phosphorus were strongly positively correlated with those mean of functional traits representing soil resource use efficiencies (leaf nitrogen concentration and phosphorus concentration).…”

How to Improve the Predictions of Plant Functional Traits on Ecosystem Functioning?

“…Trait-abundance distributions describe the shape of the frequency distribution of plant traits in a specific community and include the community-weighted mean, variance, skewness, and kurtosis. The variance, skewness, and kurtosis compensate for a weakness associated with the mean in terms of its potential to mistakenly exacerbate the role of dominant species (Liu et al, 2020 ). The variance is the functional divergence, skewness signifies the extent of asymmetric distribution of traits, and kurtosis signifies functional evenness.…”

Unveiling ecological assembly rules from commonalities in trait distributions

“…the 'Trait Driver Theory': Enquist et al, 2015Enquist et al, , 2017. Focusing on the distance to the lower boundary of the SKR (see Box 1) (Liu et al, 2020) or the deviation of individual communities from empirical to random SKRs (Gross et al, 2017)-rather than raw variations in kurtosis-may help diagnosing shifts in community evenness and community disassembly under ongoing environmental change.…”