Inter- and intraspecific variation in specific root length drives aboveground biodiversity effects in young experimental forest stands
Created at: 2016-11-03
Envisaged journal: Journal of Plant Ecology
Envisaged date: 2016-11-03
Although the net biodiversity effect (NE) can be statistically partitioned into complementarity and selection effects (CE and SE), there are different underlying mechanisms that can cause a certain partitioning. Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by inter-and intraspecific trait variation.
We measured tree height of 2493 living individuals in 57 plots and specific root length on first-order roots of 368 of these individuals across different species richness levels (1, 2, 4, 8 species) in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China (BEF-China) established in 2009. We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity (RaoQ) and further effects of species interactions by variable components of inter- and intraspecific functional diversity (community weighted trait similarity and trait dissimilarity, CWS and CWD). Finally, we examined the relationships between biodiversity effects on stand-level tree height and functional diversity (RaoQ, CWS and CWD) in specific root length using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.
Our results show that species richness significantly affected specific root length in five and tree height in ten out of 16 species. A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in specific root length. A positive CE was related to high values of all three components of root functional diversity (RaoQ, CWS and CWD). Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.
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