Large-Scale Patterns of Soil Nematodes across Grasslands on the Tibetan Plateau: Relationships with Climate, Soil and Plants

Soil nematodes are important contributors to soil biodiversity. Nonetheless, the distribution patterns and environmental drivers of soil nematode communities are poorly understood, especially at the large scale, where multiple environmental variables covary. We collected 520 soil samples from 104 sites representing alpine meadow and steppe ecosystems. First, we explored the soil nematode community characteristics and compared community patterns between the ecosystems. Then, we examined the contributions of aboveground and belowground factors on these patterns. The genus richness and abundance of nematodes on the Tibetan Plateau are lower than other alpine ecosystems, but are comparable to desert or polar ecosystems. Alpine meadows supported a higher nematode abundance and genus richness than alpine steppes; bacterial-based energy channels were pre-dominant in both the ecosystems. Soil factors explained the most variation in the soil nematode community composition in the alpine meadows, while plant factors were as essential as soil factors in the alpine steppes. Unexpectedly, the climate variables barely impacted the nematode communities. This is the first study to explore the spatial patterns of soil nematode compositions on the Tibetan Plateau, and we found that the contributions of climate, plants, and soil properties on soil nematodes community were essentially different from the previous knowledge for well-studied plant and animal communities