Distributional patterns of soil nematodes in relation to environmental variables in forest ecosystems

Understanding biodiversity and biogeographic distribution of soil fauna is an important topic in ecology. While nematode communities have been compared among ecosystems, knowledge remains limited about how environmental factors and nematode distributions are linked at different spatial scales. Here, we employed high-throughput sequencing to compare nematode communities in tropical (Xishuangbanna), subtropical (Ailaoshan), and cold temperate spruce-fir (Lijiang) forest ecosystems with identical spatial sampling. Relationships between nematode communities and environmental factors were analyzed using redundancy analysis (RDA). Our results showed that nematode richness and diversity peaked in Xishuangbanna; however, no significant differences were observed in other two forest ecosystems. Bacterial feeders and Omnivores / Carnivores (Om & Ca) had the lowest relative abundance, but the highest diversity, in Xishuangbanna, with the opposite pattern being detected for fungal and plant feeders. Our data also demonstrated that, for forest ecosystems, climate factors drive nematode communities distributions at the regional scale, while terrain and soil characteristics (including pH and nutrients) drive nematode communities distributions at local scales. This study improves our current understanding of key factors (environmental parameters) responsible for the biogeographical distribution of forest nematode communities at different spatial scales.