Litter standing crop of shrubland ecosystems in southern China

Aims Litter is an important component of terrestrial ecosystems, which plays significant roles in carbon and nutrient cycles. Quantifying regional-scale pattern of litter standing crop would improve our understanding in the mechanism of the terrestrial ecosystem carbon cycle, also with help in predicting the responses of carbon cycle of terrestrial ecosystems to future climate change. Our objective was to examine variation in litter standing crop of shrublands along the environmental gradients in southern China.
Methods During 2011-2014, we investigated the litter standing crop at 453 shrublands sites by the stratified random sampling, reflecting climatic and soil attributes across southern China.
Important findings We found that the mean value of litter standing crop in these shrubland ecosystems across southern China was 0.32 kg·m^-2. It was 68% of forest litter standing crop (0.47 kg·m^-2) and was five times higher than that in grasslands (0.06 kg·m^-2) in China. Litter standing crop increased with latitude. Our results showed that litter standing crop was negatively correlated with mean annual temperature, soil total P and soil pH, but not significantly correlated with other environmental variables, including mean annual precipitation, soil carbon, nitrogen and soil organic matter. The conversion coefficient of carbon in litter standing crop was 0.41, which is significantly lower than that of vegetation in shrublands (0.50), resulting in an overestimate in carbon storage of litter standing crop in shrubland up to 22% by applying wrong conversion coefficient. We concluded that litter standing crop of shrublands is an important component in terrestrial ecosystems. Mean annual temperature was the most important environmental variable, accounting for the variation in litter standing crop of shrublands in southern China. To our best of knowledge, this is the first study to quantify variation in litter standing crop of shrublands at the regional scale. Therefore, our study will have important implications for assessing the carbon budget of terrestrial ecosystems in China.