Effects of functional composition on plant competitors, stress-tolerators, ruderals ecological strategies in forest communities across different climatic zones.

Ecological strategies identified by plant functional traits are valuable descriptors for understanding species, populations, communities, and ecosystems in response to environmental conditions. Ecological strategies, in conjunction with the functional structure of plant communities, serve as crucial tools for investigating complex relationships among the environment, vegetation, and ecosystem functions. However, it remains unclear whether the functional structure (specifically, community-weighted mean [CWM] traits) accurately reflects the optimal ecological strategies in forest communities. Here, we gathered seven functional traits for each species from four distinct forest vegetation types across four climatic zones, including leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf phosphorus concentration (LPC), leaf nitrogen concentration (LNC), wood density (WD) and maximum plant height (H). We based on CSR (Competitors, Stress-tolerators, Ruderals) theory and "StrateFy" ordination method utilizing LA, LDMC and SLA to position them within CSR triangle and categorize them into four ecological strategy groups: Competitive, Stress-tolerant, Intermediate, and Ruderal ecological strategy groups (C-group, S-group, Int-group, and R-group). We then determined the proportion of species in each group. Subsequently, we calculated the CWM trait values for the remaining four functional traits: WD (CWM-WD), LPC (CWM-LPC), LNC (CWM-LNC) and H (CWM-H). Non-metric multidimensional scaling and hierarchical partitioning revealed that CWM-WD, CWM-LPC, CWM-LNC and CWM-H significantly influenced the ecological strategies of forest communities. The synergistic interaction of CWM-WD and CWM-LPC had the most significant impact on ecological strategies within forest communities. Notably, CWM-WD emerged as the most crucial single CWM trait for explaining variation in ecological strategies within forest communities. In conclusion, our study demonstrates that CWM traits effectively reflect optimal CSR ecological strategies in forest communities across different climatic zones, with CWM-WD serving as a preferred indicator. This can improve our critical insights into key ecological processes in forest communities using trait-based approach.