Soil nematode community response to warming in alpine meadows of northern Tibet

To understand the effect of warming on soil nematode communities in alpine meadows, soil nematode communities were compared in short-term and long-term warming by OTC (open top chamber)simulation in northern Tibet. The results showed that the community composition of soil nematodes was changed and the abundance of Ditylenchus and Acrobeles were increased by short-term and long-term warming. The abundance of fungivores (Fu) was increased significantly by long-term warming; however, the abundance of bacterivores (Ba), plant-parasites (Pp), predators/omnivores (Om), and cp1-5 groups was not significantly different among the treatments studied. The diversity and evenness of soil nematodes were reduced by both short-term and long-term warming. The diversity of soil nematodes in 2015 was significantly reduced in the short-term warming treatment. As compared with the control, the number of soil nematodes in the short-term and long-term treatments was significantly decreased in 2015 and 2016. The values were decreased by 34.45% and 32.09% in 2015 and 25.34% and 22.66% in 2016, respectively. The effect of warming on MI, NCR, PPI, and WI index were not significant in the study treatments, and WI > 1, NCR > 0.5, showed that warming had a little effect on the health of alpine meadows. Moreover, the decomposition of organic matter depended mainly on Fu and Ba in this study. The correlations among environmental factors and the number soil nematodes were analyzed by redundancy analysis. The results showed that the total plant cover, Cyperaceae cover, soil temperature and moisture, and number of bacteria and fungi were important factors affecting the number of total nematodes, Ba, Fu, Pp, and Om. Therefore, certain changes in nematode community structure and composition have taken place due to the plants, soil, physical, and chemical properties, and the number of microbes were changed by raising temperature in alpine meadows.