Community Characteristics And Niche Analysis Of Soil Fauna In Returning Farmland To Forest Areas In Wuqi County,Shannxi Province

Soil fauna are the main biological organisms of soil ecosystems,an important carrier of litter decomposition and nutrient circulation,and are extremely sensitive to environmental changes.Soil fauna have been used as the main indicators for evaluating the quality of the soil environment.Ecological niche theory is the basic theory to elucidate species competition and coexistence.The study of population ecological niches is of great significance in explaining species adaptability,interspecific relationships,and community succession.However,there are few reports on soil animal ecological niche in the reforested areas on Loess Plateau,which limits people’s understanding of the utilization of soil animal resources,community stability and succession process in this area.Therefore,in order to understand the influence of different vegetation types on soil animal community characteristics and their ecological niche characteristics in the conversion of farmland to forests area,this study selected six typical vegetation types in the Jin Foping and Hegou small watershed at Wuqi county,and conducted four sampling surveys in the study area in April,July,September and December 2021.The soil macrofaunas were taken by handsorting and the meso and microfauna were separated by Tullgren method and Baerman method.The composition,density,number of groups and diversity characteristics of soil fauna at different vegetation types were analyzed.In this study,principal component analysis(PCA),correlation analysis(Pearson),and redundancy sorting analysis(RDA)were used to explore the structure of soil fauna at different vegetation types and their main influencing factors.And,the ecological niche width and overlap of soil fauna of different vegetation types are calculated and compared,and the total ecological niche width,overlap value and ecological response rate of soil fauna in the research area are studied.The purpose of this research is to understand the community characteristics and ecological characteristics of soil fauna in the research area and their relationship with environmental factors,and to provide certain insights into people’s understanding of the resource utilization and community stability of soil fauna in the conversion of farmland to forests.The main research results are as follows:(1)In this research,a total of 13715 identifiable soil fauna were collected,belonging to 3 phyla,8 orders,26 orders and 72 families,with rich groups,and arthropod phylum dominated the soil fauna.The dominant groups are Oribatida,Prostigmata and Collembolal larvae,and common groups include 7 groups including Dipteral larvae,Formicidae,Coleopteral larvae,Rhabditia,Entomobryidae,and Julidae,and rare groups account for relatively small,but more species.(2)Overall,the number of individuals,groups and diversity of soil fauna communities in Robinia pseudoacacia,Hippophae rhamnoide and Armeniaca sibirica × Hippophae rhamnoides.The soil available potassium content,p H,water content,total capillary porosity,non-capillary porosity,total nitrogen,and organic carbon are the main soil factors affect the distribution pattern of soil animal communities.(3)The total ecological niche width of soil animal groups such as Gnaphosidae,Prostigmata and Coleopteral larvae is larger,the utilization of space resources is higher,the ecological adaptation range is wider,and it tends to generaliz species.The spectrum of available resources of the same soil animal groups varies with different vegetation.The largest ecological niche width of more soil animal groups exists in Robinia pseudoacacia and Armeniaca sibirica × Hippophae rhamnoides.The smallest ecological niche width exists in Pinus tabulaeformis.(4)The total ecological niche overlap of the main groups of soil fauna in the study area in the spatial dimension is large,and the sum of ecological response rates is negative.The main groups of soil fauna are in a declining stage.Soil p H,capillary porosity,and available phosphorus are the dominant factors affecting the ecological characteristics of soil fauna,and indicators such as organic carbon,total nitrogen,total phosphorus,alkaline nitrogen,and bulk density also have a certain impact on them.In summary,in the area of returning farmland to forest in Wuqi county,the sub-forest environment of Robinia pseudoacacia and Armeniaca sibirica × Hippophae rhamnoides mixed forest is superior,which is more suitable for the survival and reproduction of soil fauna;Gnaphosidae,Prostigmata,Coleopteral larvae can adapt to various understory environments and tend to generalize species;The interspecific competition of soil fauna in the study area was fierce,the stability was poor,and the community was developing towards the top community.