Linking leaf δ15N and δ13C with soil fungal biodiversity, ectomycorrhizal and plant pathogenic abundance in forest ecosystems of China

Leaf delta(15) N and delta C-13 are important functional traits in biogeographic studies of forest ecosystems. However, little is known about their relationships with soil fungal biodiversity, ectomycorrhizal and plant pathogenic abundance at large scales. In this study, leaf and soil samples were collected from 33 forest reserves along a large range across China to explore the associations between leaf delta N-15 and delta C-13 and soil fungal biodiversity, ectomycorrhizal and plant pathogenic relative abundance, using molecular and stable isotope techniques. Leaf delta N-15 was significantly positively correlated with the soil fungal Shannon index, significantly negatively correlated with the relative abundance of plant pathogens, and significantly positively correlated with the relative abundance of ectomycorrhizas. Leaf delta C-13 was significantly positively correlated with the relative abundance of ectomycorrhizas and significantly inverted unimodal correlated with the relative abundance of plant pathogens. Soil-plant-microbial interactions may contribute to variations in leaf delta N-15, delta C-13, and soil fungal communities among different types of forest ecosystems. Temperature and precipitation were the main factors that affected large-scale latitudinal and longitudinal biogeographic patterns. Leaf delta N-15 was mainly affected by the relative abundance of ectomycorrhizal fungi and leaf delta C-13 was affected by the mean annual temperature and mean annual precipitation. Leaf delta N-15 and delta C-13 may be indicators that reflect soil fungal communities in forest ecosystems.