Effects Of Different Grazing Intensities On Soil Nematode Community Composition And Diversity In Stipa Breviflora Desert Steppe

Soil nematodes,as the most abundant of soil animals,have been maintaining the healthy ecosystem and are sensitive to environmental changes,Nematode has been increasingly used as an indicator organism to reflect the biodiversity and soil health status of various regions in recent years.To investigate the response of soil nematode community to different grazing intensities in Stipa breviflora steppe,this study was conducted based on high-throughput sequencing technology,relying on Inner Mongolia Stipa breviflora desert steppe long-term grazing experimental base platform,using a completely random block test design,and with four different stocking rates,no grazing(CK),light grazing(LG),moderate grazing(MG),heavy grazing(HG).The aim is to understand the variation of soil nematodes in desert steppe under different grazing intensities.The results showed as follows:(1)Soil physical and chemical properties were affected by different grazing intensities,and grazing decreased soil organic carbon and total nitrogen,especially under heavy grazing.Soil factors such as available ammonium phosphate and nitrate nitrogen had significant effects on the abundance of soil nematode,and thus affected the community structure of soil nematode.(2)There were significant differences in the species(genus)and number of soil nematode under different grazing intensities.A total of 318 nematode OTUs were detected in the samples.Light grazing(LG)significantly increased the number of nematode species(genus),while heavy grazing(HG)significantly decreased the number of nematode species(genus).Light grazing was less influence on nematode community,moderate grazing increased the richness of nematode and heavy grazing changed the structure of nematode community.And soil nematodes community species richness highest under moderate grazing,suggests that moderate grazing most conducive to the stability of soil nematode community.(3)Based on the analysis of stochastic forest optimal model,we found that the species important values of Aporcella Discolaimus Aphelenchoides Longidorella and Acrobeles were greater than 2 in random forest prediction model,and these species may be the key genera of soil nematodes in different intensities in Inner Mongolia desert steppe.