Litter richness, functional identity, and chemical properties affect soil properties in boreal forest soil in Northeast China: a laboratory study

Litter decomposition is the main source of forest soil carbon (C) and nitrogen (N), which is critical for maintaining ecosystem function and stability. Exploring the impact of litter diversity on soil C and N will provide the basis for afforestation tree species selection and forest management. However, the influences of leaf litter diversity, functional identity, and chemical properties on soil properties are less known. This study investigated their effects on soil C and N in boreal forest soil in Northeast China. Fresh leaf litter from 8 dominant tree species in Northeast China was collected. The soil was mixed with litter from single species and all combinations of 2, 4, and 8 species (321 treatments). The soil C and N parameters were measured. Tree species richness and AM tree fraction of leaf litter promoted soil organic carbon (SOC) stability by decreasing soil respiration rate (Rs) and temperature sensitivity (Q10). The concentrations of SOC, total nitrogen (TN), microbial mass C and N (MBC and MBN) increased with the increase in tree species richness and AM tree fraction of leaf litter. Variance partitioning analysis showed that AM tree fraction of leaf litter explained 3.86 times more variation of soil C and N than tree species richness of leaf litter, which directly or indirectly influenced them via litter chemical properties. This study provides the basis for understanding the importance of litter diversity, and chemical properties for soil C and N and highlights the importance of AM tree fraction of leaf litter for soil properties.