Aim: Forests play a key role in regulating the global carbon
cycle, a substantial portion of which is stored in aboveground biomass
(AGB). It is well-understood that biodiversity can increase the
biomass through complementarity and mass-ratio effects, and the
contribution of environmental factors and stand structure attributes to
AGB was also observed. However, the relative influence of these factors
in determining the AGB of Quercus forests remains poorly
understood. Location: Temperate Quercus forests in
northeastern China. Methods: Using a large dataset retrieved
from 523 permanent forest inventory plots across Northeast China, we
examined the effects of integrated multiple tree species diversity
components (i.e., species richness, functional and phylogenetic
diversity), functional traits composition, environmental factors
(climate and soil), stand age, and structure attributes (stand density,
tree size diversity) on AGB based on structural equation models.
Results: We found that species richness and phylogenetic
diversity both were not correlated with AGB. However, functional
diversity positively affected AGB via an indirect effect in line with
the complementarity effect. Moreover, the community-weighted mean of
specific leaf area and height increased AGB directly and indirectly,
respectively; demonstrating the mass-ratio effect. Furthermore, stand
age, density, and tree size diversity were more important modulators of
AGB than biodiversity. Main conclusions: Our study highlights
that biodiversity-AGB interaction is dependent on the regulation of
stand structure that can be even more important for maintaining high
biomass than biodiversity in temperate Quercus forests.
Mass‐ratio and complementarity effects simultaneously drive aboveground biomass in temperate
Quercus
forests through stand structure