Diversity-decomposition relationships in forests worldwide

Plant species diversity affects carbon and nutrient cycling during litter decomposition, yet the generality of the direction of this effect and its magnitude remain uncertain. With a meta-analysis including 65 field studies across the Earth’s major forest ecosystems, we showed here that on average decomposition was faster when litter was composed of more than one species. These positive biodiversity effects were mostly driven by temperate forests, but more variable in other forests. Litter mixture effects emerged most strongly in early decomposition stages and were related to divergence in litter quality. Litter diversity also accelerated nitrogen, but not phosphorus release, potentially indicating a decoupling of nitrogen and phosphorus cycling and perhaps a shift in ecosystem nutrient limitation with changing biodiversity. Our findings demonstrate the importance of litter diversity effects for carbon and nutrient dynamics during decomposition, and show how these effects vary with litter traits, decomposer complexity and forest characteristics.

Methods
All the data were extracted from the corresponding references using GetData Graph Digitizer. The effect sizes for mass loss, N release and P release were calculated in MetaWin.