Abstract: To understand the responses of soil nematodes in alpine forests of the Tibet Plateau to altitude and forest gaps, differences in soil nematode communities among elevations and between forest and forest gaps in an Abies georgei var. smithii forest of the Sejila Mountains in southeast Tibet were analyzed using high-throughput sequencing techniques. The results showed that soil nematode diversity increased with decreasing altitude, while nematode diversity was slightly higher in forest gaps than within forests without statistical significance at the same elevation. Enoplea and Triplonchida were the most dominant taxa at mid-elevation (4292 m). The soil nematode community structure varied significantly with the altitude, but exhibited similar between the gap and the forest.  Soil water content, phosphorus content (including total and available phosphorus), and nickel content were the major factors affecting soil nematode diversity, while soil heavy metal and nutrient changes induced by forest gaps were the key factors affecting soil nematode community structure.

Key words: soil nematode community, elevation, forest gap, Abies georgei var. smithii forest, Sejila Mountain