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 trait-based community assembly. Our results highlight the principles of community assembly regarding multi-dimensionsional traits in natural forests at a regional scale.
Highlights
How plant communities assemble and persist has been a fundamental question of ecology (Götzenberger et al, 2012), and trait-based approaches have recently been proposed as an effective way to reveal the underlying principles (Mcgill et al, 2006; Westoby and Wright, 2006; Cadotte, 2011)
Nine typical forests were selected along the 3700-km northsouth transect of China (NSTEC), and they were designated as Jianfengling (JF), Dinghu Mountain (DH), Jiulian Mountain (JL), Shennongjia (SN), Taiyue Mountain (TY), Dongling Mountain (DL), Changbai Mountain (CB), Liangshui (LS), and Huzhong (HZ) (Figure 1)
From species to community level, some trait-trait relationships changed from non-correlation to positive or negative correlation, such as stomatal size (s) versus palisade tissue thickness (PT), stomatal area fraction (f ) versus spongy tissue thickness (ST); some trait-trait relationships became stronger, such as nitrogen content (N) versus specific leaf area (SLA), stomatal density (d) versus s
Summary
How plant communities assemble and persist has been a fundamental question of ecology (Götzenberger et al, 2012), and trait-based approaches have recently been proposed as an effective way to reveal the underlying principles (Mcgill et al, 2006; Westoby and Wright, 2006; Cadotte, 2011). Leaf Traits and Optimal Community Assembly filtering reduces the range of trait values (Cornwell et al, 2006; Cornwell and Ackerly, 2009; Bernardverdier et al, 2012) These studies expanded our understanding of trait-based community assembly, it is still unclear how multi-dimensional traits (such as leaf economic, hydraulic, and anatomical traits) and their interaction determine community assembly processes. Some arise due to concerted convergence of the two traits, i.e., each trait contributes independently to an advantage in the given environment Despite these varying mechanisms underlying trait-trait relations, certain relationships between leaf traits are of exceptional importance given their consistent slopes across species among vastly different biomes (Reich et al, 1999). While some studies have investigated the coordination between leaf economics and hydraulic traits at the species level (Li et al, 2015; Yin et al, 2018), little knowledge concerning whether these two sets of traits vary in a fully coordinated manner or whether independent variation would decouple such relations at the community level
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