Effect of Litter Quality on Leaf-Litter Decomposition in the Context of Home-Field Advantage and Non-Additive Effects in Temperate Forests in China

Litter quality is often considered the main driver of rates of decomposition. Litter decomposes faster in its home environment than in any other environment, which is called the home-field advantage (HFA). However, evidence for this phenomenon has not been universal. In addition, litter mixtures of different species can induce a non-additive effect (NAE) on decomposition processes. However, the direction and magnitude of NAE vary and underlying mechanisms remain unclear. The aim of our study was to assess the effect of litter quality on leaf-litter decomposition in the context of HFA and NAEs in temperate forests in China. Litterbags containing aspen (Populus davidiana), birch (Betula platyphylla), and oak (Quercus liaotungensis) litter were incubated in situ in pure aspen and broadleaved mixed forests in Chinese temperate forests for 360 days. The main results were: 1. Aspen litter with a low C/N ratio and high initial N concentration decomposed faster than birch litter, both of which decomposed faster than oak litter, which had the lowest quality. 2. The rate of decomposition of oak litter was significantly higher in the broadleaved mixed forest than in pure aspen stands; however, the rate of decomposition of birch litter was not significantly different from pure aspen stands and broadleaved mixed forest. 3. Contrary to what was predicted, the mixture of aspen and birch litter decomposed faster than expected. However, both the aspen/oak and birch/oak mixtures had a neutral mixing effect where the rates of decomposition were slightly faster than expected. 4. Controlling factors based on linear models show that the order of the relative importance of their effect on litter decomposition was as follows: litter quality, forest floor environment, and litter