Effects Of Grazing Livestock Type And Intensity On Ground-dwelling Arthropod Communities In Typical Steppe Of Inner Mongolia

Grassland ecosystem covers aproximately two-fifth of the world’s land area,and has important ecosystem services such as maintaining biodiversity,preventing wind erosion,and conserving water and soil.Arthropoda is the most abundant taxonomic group in grassland ecosystem,playing a key role in ecosystem functioning such as litter decomposition and carbon and nitrogen cycles.Grazing is the major grassland use type.Many studies have been done on the impacts of grazing on plant communities,but much less on the impacts on soil faunal communities,especially no systematic research on the effects of grazing animal type and intensity on ground-dwelling arthropods.Livestock grazing directly and indirectly affect arthropod communities through selective feeding,trampling and faeces decomposition,including the complex interspecific competition.We studied the changes in ground-dwelling arthropod communities across the treatments of sheep grazing intensities(no,light,moderate and heavy grazing)and livestock types(sheep,goat and cattle)in the Xilingol typical steppe grassland in Inner Mongolia.Ground-dwelling arthropods were captured by trap method and most species were identified to the level of family.Shannon.Wiener diversity index,Simpson dominance index and Pielou evenness index were calculated,and analysed the relationship between the ground-dwelling arthropods and environmental factors.The results were as follows:1.In this study,a total of 16,338(or 15,571)ground-dwelling arthropods were captured from the sheep-grazed experimental grassland at different grazing intensities(or from the experimental grasslands grazed at a moderate intensity by sheep,goat or cattle).All ground-dwelling arthropods belong to 10 orders,73 families,and a total of 83 taxa.The dominant groups are Acridoidea and Carabidae.2.Compared with no-grazing treatment,light grazing increased the number of ground-dwelling arthropods,and the increase became smaller with the increase of grazing intensity;Other grazing intensities and moderate grazing of different livestock type had no significant effects on arthropod community abundance,number,biomass and diversity.3.The heavy grazing reduced the biomass of ground-dwelling arthropods in spring and summer,and the reduction of predatory arthropods was most significant.Grazing sheep and cattle increased the number of omnivorous arthropods,while grazing goats reduced the abundance of omnivorous.The grazing reduced the abundance of phytophagous arthropods.The biomass of parasitic insects in different grazing livestock grassland was higher than that in no-grazing grassland.4.The ground-dwelling arthropods showed larger abundance,number,and biomass in summer,though grasshoppers were more abundant in autumn.The diversity of ground-dwelling arthropods was less affected by grazing,but showed a clear seasonal and interannual changes.In conclusion,our results show that grazing has little impact on the abundance of ground-dwelling arthropod communities,but large effect on the composition of different arthropod guilds.The ground-dwelling arthropod commuity has clear seasonal and interannual changes in response to weather changes.The abundance and biomass of various guilds of ground-dwelling arthropods are high in summer,while the abundance and biomass of phytophagous dominated by grasshoppers are the highest in autumn.The information on the responses of different arthropod guilds to livestock grazing are useful in developing management regimes for sustainable management of natural grasslands.