Functional diversity (FD) and Functional identity [FI, measured by Community Weighted Mean (CWM)] are core trait-based descriptors of community structure that capture how species assemblages are organized in functional trait space. Describing their spatial structure and distribution of FD/CWM is critical to understanding how plant communities are structured across a broad environmental gradient. While many studies have documented climate effects on community composition and functional structure, large-scale, cross-biome synthesis of FD/CWM patterns is limited, especially in a unified, data-driven framework. Lack of such spatially explicit synthesis prevents us from identifying major climatic and environmental gradients associated with community functional structure across macrolevel biomes and to understand how these functional structures shift under contrasting environmental contexts.
Here we synthesize and map large-scale patterns of FD/CWM across North America using forest inventory data. Specifically, we provide a data-driven description of their spatial structure, distribution, and climatic/environmental factors of FD/CWM in boreal, temperate, and sub-tropical forests spanning both humid and xeric climatic regions. By quantifying how FD and CWM vary across broad climatic gradients, this study establishes a continental-scale baseline for understanding large spatial patterns of tree functional structure and their environmental context. tree functional structures.