Divergent Controls on Leaf and Root Litter Decay Linking to Soil C, N, and P Pools Under a Subtropical Land-use Change

Land-use changes affect terrestrial ecosystem carbon (C), nitrogen (N), and phosphorus (P) dynamics directly by altering above- and belowground litter inputs and decomposition, although the determining factors and their linkage to soil C, N, and P pools remain limited. Here, we investigated litter, soil, and microbial attributes during leaf and fine-root decomposition linked with soil C, N, and P pools under subtropical land-use change (that is, cropland, shrubland, and woodland). We found that leaf litter decomposed faster in shrubland than in woodland and cropland, while the fine root of cropland decomposed more than those of shrubland and woodland. Leaf and fine-root decomposition was not correlated, whereas leaf and fine-root litter quality was positively correlated. Leaf litter decomposition was considerably dependent on litter quality and soil moisture, whereas fine-root decomposition was predominantly predicted by bacterial biomass. Litter C quality in afforested lands (woodland and shrubland) substantially stimulated soil organic C accumulation primarily by the input of new fine-root-derived soil organic C. Soil total N accumulation in woodland was tightly associated with litter quality of fine root and microbial attributes, but soil total P formation in shrubland was strongly correlated with leaf litter quality and microbial attributes. These findings indicated that the variations in decomposition of leaf and fine root were mediated by different combinations of litter, soil, and microbial traits, which caused the difference in the soil C, N, and P accumulation following land-use change. Overall, our results revealed contrasting dynamics of above- and belowground litter decomposition, uncovered diverse influences on soil C, N, and P pools, and provided novel insights into accurately predicting soil C, N, and P dynamics after afforestation.