Leaf litter decomposition characteristics and controlling factors across two contrasting forest types

Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems. In addition to traditional environmental factors, the degradation process of litter is also affected by plant functional traits and litter quality. However, at the community level, it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent. A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain, Beijing, North China, including six monodominant communities dominated by Juglans mandshurica, Populus cathayana, Betula dahurica, B. platyphylla, Pinus tabuliformis and Larix gmelinii var. principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla, Quercus mongolica and Tilia mongolica. The results showed that there were considerable differences in the litter decomposition rate (k-rate) among the different forest types. The community weighted mean (CWM) traits of green leaves and litter quality explained 35.60% and 9.05% of the k-rate variations, respectively, and the interpretation rate of their interaction was 23.37%, indicating that the CWM traits and their interaction with litter quality were the main factors affecting the k-rate variations. In the RDA, leaf nitrogen content, leaf dry matter content, leaf tannin content and specific leaf area were the main factors affecting the k-rate variations. Therefore, we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.