Soil Fauna Diversity And Ecological Distribution Of Sophora Alopecuroides Under Different Succession Series In Degraded Grassland Of Yili

In recent years,due to the over exploitation of resources and the increase of human activities,a large area of grassland degradation occurred in the Yili River Basin of Xinjiang,and a large number of poisonous weeds took the opportunity to spread.Sophora alopecuroides L.,as a typical representative plant with fast growth and strong invasiveness,has become the dominant community in a short time,which has a great impact on the local ecological diversity and agricultural production.The community composition and ecological distribution of soil animals in different succession series of Sophora alopecuroides are different.The study of soil animal density,group number and diversity characteristics can clearly reflect the degradation degree of Yili grassland in Xinjiang.In order to study the diversity of soil fauna and its response to environmental factors under different succession series of Sophora alopecuroides in Yili degraded grassland,soil fauna of 6 habitats including Salsolacollina community,Artemisia transitiensis community,Leymus chinensis community,Sophora alopecuroides light succession community,Sophora alopecuroides moderate succession community and Sophora alopecuroides heavy succession community were selected in may(spring),July(summer)and October(Autumn)of 2019 Soil animals are the research objects.The distribution and seasonal dynamics of soil animal diversity in different succession series of Sophora alopecuroides were analyzed.Redundancy analysis(RDA)method was used to explore the correlation between soil animal diversity and environmental factors under different succession series of Sophora alopecuroides,so as to reveal the ecological mechanism of soil animal rapid diffusion of Sophora alopecuroides in arid and semi-arid areas,and provide theoretical basis for the reconstruction and protection of degraded grassland in Ili.The main conclusions are as follows:(1)A total of 6917 soil animals,43 classes,belonging to 2 phyla,6 classes,20 orders and 43 families were found in the six successional habitats of Sophora alopecuroides.Among them,there were 1474 soil macrofauna belonging to 31 classes,belonging to 24 families,10 orders,4 classes,and the average density of soil macrofauna is 262.04 one square meter.The two dominant groups were formicidae and elateridae larvae accounting for 50.47% of the total density of soil macrofauna in different succession series of Sophora alopecuroides.There are 11 common groups(43.08%),most of which are coleoptera larvae,scarabaeidae larvae,carabidae,araneida,etc.There are 18 rare groups(6.45%).In addition,there are 36 kinds of soil meso-microfauna,5443 of which belong to 2 phyla,6 classes,20 orders(suborders)and 26 families.The average density of soil meso-microfauna is 6047.78 one square meter.The two dominant groups were oribatida and actinedida,accounting for65.37% of the total density of soil meso-microfauna in different successional series of Sophora alopecuroides.There are 7 common groups(28.46%),most of which are gamasida,isotomidae,formicidae etc.The rare group(6.17%)is small in number but large in species,with a total of 27 groups.(2)By observing the horizontal distribution of soil fauna diversity in different succession series of Sophora alopecuroides,it was found that the diversity of soil macrofauna and meso-microfauna of Sophora alopecuroides heavy succession community was the highest among the six successional habitats,while the diversity of Sophora alopecuroides light succession community and Salsolacollina habitat was lower.There were significant seasonal differences in the diversity distribution of soil macrofauna and meso-microfauna in different succession series of Sophora alopecuroides.In terms of soil macrofauna diversity of degraded grassland in Yili,in spring and summer,Sophora alopecuroides light succession community was the lowest,Sophora alopecuroides heavy succession community was the highest in spring,and the Artemisia transitiensis community was the highest in summer.In autumn,Sophora alopecuroides heavy succession community was the highest,and Salsolacollina community was the lowest.In terms of soil meso-microfauna diversity of degraded grassland in Yili,in spring and summer,Sophora alopecuroides light succession community was the lowest,Sophora alopecuroides heavy succession community was the highest.In autumn,the diversity of soil meso-microfauna in Salsolacollina community was low,and Sophora alopecuroides mild succession community was the highest.The results showed that the highest Shannon-Wiener index(H')and Margalef index(D)of soil fauna in the six successional habitats were Sophora alopecuroides heavy successional community,the higher Picelou index(e)were Salsolacollina community and Artemisia transitiensis community,and the higher Simpson index(C)were Leymus chinensis community and Sophora alopecuroides light successional community.(3)By observing the vertical distribution of soil fauna diversity in different succession series of Sophora alopecuroides,it was found that with the increase of soil depth,the soil fauna diversity in Yili degraded grassland decreased layer by layer.In0cm?5cm ? 5cm?10cm and 10cm?15cm,the soil fauna diversity of Sophora alopecuroides heavy succession community was the highest in the six successional habitats.In the soil layer of 15cm?20cm,the diversity of soil macrofauna of Sophora alopecuroides heavy succession community,Sophora alopecuroides moderate succession community and Artemisia transitiensis community were the highest.(4)The results of RDA analysis showed that there was a significant correlation between soil physical-chemical factors and soil fauna diversity.Among the environmental factors,soil organic matter,total nitrogen,available nitrogen,total phosphorus,available phosphorus,available potassium and p H were the key factors affecting the distribution of common soil fauna diversity in different succession series of Yili degraded grassland(p< 0.01).