Abstract:

Soil nematodes are key components in the soil food web, playing a crucial role in the regulation of nutrient cycling and energy flow. Many studies have documented the importance of the soil environment in regulating variation in taxonomic diversity over space and time, though little is known about how soil environment influences the functional diversity of soil nematodes. We investigated soil nematode communities in alpine meadows distributed on contrasting environmental regimes (valley floor, northern slope, southern slope, and ridge top) at each of three sites on the Tibetan Plateau. We examined the association between soil environmental factors and the functional diversity of soil nematodes using the community-weighted mean of body-size (CWM) and the Rao functional diversity of body-size (FD_Rao). Our results showed that the taxonomic diversity of soil nematodes increased significantly with soil pH while the functional diversity of soil nematodes is associated with soil fertility (i.e. CWM and FD_Rao are positively correlated with soil organic matter and nitrogen content while negatively with soil total phosphorus). Results also revealed that the abundance of bacterivores and fungivores are significantly greater in valley floor plots. The abundance of herbivores and omnivore-predators are lesser at ridge top plots, with abundance of most functional groups positively correlated with soil phosphorous content, but negatively with plant species richness. Our study suggests that soil nematode taxonomic and functional diversity exhibit a decoupled response to soil environmental factors, providing new insight into our understanding of biodiversity assembly in soil animals in Tibetan alpine meadows.

Key words: alpine meadow, soil nematodes, soil environment, functional diversity, taxonomic diversity, soil phosphorus