The spatial patterns of litter turnover time in Chinese terrestrial ecosystems

The feedback between plant, soil and climate is partly determined by plant litter turnover time, which is influenced by climate, litter quality and soil properties. However, the spatial patterns of litter turnover time and its interrelation with these variables are rarely quantified. With a database of 1,378 litter turnover times and key associated climate, litter quality and soil properties (total of 20 variables), this study investigated the driving factors and spatial patterns of litter turnover time across Chinese terrestrial ecosystems. The mean litter turnover time was the longest in forest ecosystems, followed by that in grassland and cropland ecosystems. The litter turnover time varied significantly depending on the litter quality and climate zone, and increased exponentially as latitude increased. Mean annual temperature (MAT) and mean annual precipitation (MAP) could accurately predict litter turnover time via negative exponential equations. Among these variables, MAT had the greatest influence on litter turnover time, which accounted for 37.4% of the variation, followed by litter quality (ecosystem types, litter types, C:N of litter and lignin content; 33.4%) and soil properties (sand content, soil pH and soil organic carbon (SOC); 29.2%) based on a boosted regression tree (BRT) model. Path analysis identified that MAT negatively affected litter turnover time both directly and indirectly through regulating soil properties and litter quality, which positively and directly affected litter turnover time. Finally, the spatial patterns of litter turnover time were obtained with a regional dataset of ecosystem types, MAT, sand content, soil pH and SOC as BRT model drivers. Overall, our results suggest that climate variables have contrasting effects on litter turnover time and could mediate the impact on litter turnover time by litter quality and soil properties. These results highlight important implications for climate-smart soil management and can be used to create reliable model predictions. Highlights: We explored the driving factors and spatial patterns of litter turnover time in various ecosystems Accurate estimates of litter turnover time were obtained from dataset from 1,378 experimental sites Litter turnover time exponentially increased as latitude increased Climate-mediated litter quality and soil properties controlled the litter turnover time.