Abundance and diversity of soil nematode community at different altitudes in cold-temperate montane forests in northeast China

Soil nematode is an essential component of the soil micro-food web and plays an important role in soil nutrient cycling. The biogeographic distribution pattern of the soil nematode community and its main driving factors have attained greater attention in the last few decades. However, previous studies mainly focused on low and middle latitudes, and few studies were conducted in cold and temperate regions at high latitudes. The structure and diversity of soil nematodes along the altitudinal gradient are still unclear, which prevents understanding and comparing the diversity of soil nematodes at different spatial scales. In this study, six altitudes (750, 830, 950, 1100, 1300, and 1420 m) were set in the Oakley Mountain in the cold-temperate zone in China, and Illumina MiSeq sequencing method was used to explore the community composition and structural characteristics of soil nematodes in 0- to 10-cm soil. The diversity of soil nematode community in a high-latitude cold-temperate zone showed a decreasing pattern of monotonicity along the altitudinal gradient. One phylum, 3 classes, 11 orders, and 43 genera were identified; plant–parasites were the dominant trophic groups at each altitude. Altitude was the main factor affecting the diversity of soil nematodes at higher latitudes. Sobs, Chao1, Shannon index, and Faith's phylogenetic diversity all showed a downward trend with the increase in altitude. Soil bulk density, soil temperature, pH, soluble organic carbon, and soluble organic nitrogen were significant factors affecting the altitude distribution of soil nematodes. Soil pH and soluble organic nitrogen were the key factors to explain the changes in the community composition of nematodes