Variation in functional trait diversity from tropical to cold-temperate forests and linkage to productivity

Abstract

Functional trait diversity is an integrative plant trait index that represents an emerging and promising approach for exploring gross primary productivity (GPP); however, it is necessary to determine how these indices vary at large scales in natural forests to establish their linkage to GPP. Here, we explored spatial variation in functional diversity and underlying linkages to GPP in the natural forests of China. Specifically, we consistently measured 10 leaf traits related to the GPP of 366 tree species in nine typical forests along the North-South Transect of Eastern China and calculated three functional diversity indices (functional richness, FRic; functional evenness, FEve; and functional divergence, FDiv) for each community. All three indices consistently varied in different directions along the transect, due to the impact of climate (temperature and precipitation). FRic increased with temperature and precipitation, whereas FDiv decreased. FRic and FDiv (but not FEve) were identified as important metrics influencing GPP at large scales. Functional diversity, climate, and soil combined explained 90.4% of total variation in GPP from cold-temperate to tropical forests. The results confirmed that there is spatial variation in functional trait diversity, and that functional diversity is important for determining spatial variation in GPP in natural forests at large scales and should be integrated into ecological models.