Spatial characteristics in decomposition rate of foliar litter and controlling factors in Chinese forest ecosystems

Aims We aim to construct a national database for decomposition rate of forest foliar litter and to investigate the effects of controlling factors concerning geography (i.e. latitude, longitude, and altitude), climate (i.e. mean annual temperature and mean annual precipitation), and litter quality (i.e. the concentrations of N, P, K, and lignin, C:N ratio, and lignin:N ratio) on litter decomposition.
Methods We compiled a large dataset on decomposition constant (i.e. k value, which indicates the rate of litter decomposition) for foliar litter in Chinese forest ecosystems covering 74 study sites, and conducted simple and multiple regression analyses to explore the relationships of the k value with the controlling factors at the national scale.
Important findings The k value showed a tendency to decrease with latitude, longitude, altitude, lignin content, C:N, and lignin:N of litter, and to increase with mean annual temperature, mean annual precipitation, and litter nutrient concentrations (N, P and K) at the national scale. Single factors such as climate, litter quality, and geographic variable only explained 0.1%-30.3% of the variation in the rate of litter decomposition. However, a combination of climatic factors (mean annual temperature and mean annual precipitation) and latitude accounted for 34.1% of the variation in the rate of litter decomposition. Similarly, a combination of N, K, lignin, and lignin:N accounted for 21.7% of the variation in the rate of litter decomposition. Altitude, mean annual temperature, mean annual precipitation, N, K, and lignin:N collectively accounted for 74.4% of the variation in the rate of litter decomposition. Our results suggest that climate is the most important regulator of litter decomposition at the national scale and that the effects of litter quality is relatively small compared to climate.