沙质草地生境中大型土壤动物对土地沙漠化的响应

Abstract

Changes in soil macro-fauna community structure,as a major aspect of biological processes of desertification,are very important for us to understand the laws of biological degradation in sandy grassland and to take proper policy to desertification control.Meantime,it is very important for the restoration of soil faunal diversity in desertification,which further beneficial for the fixation of mobile sand land and desertification control.A survey of soil macro-faunal community was conducted by hand sorting in five habitats which represented various desertification stages,such as mobile sand land,semi-mobile sand land,semi-fixed sand land,fixed sand land and inter-dune land.The relation of soil faunal diversity and biomass to desertification was analyzed to assess the influences of desertification development on biological processes in Horqin Sand Land.According to the classification of soil macro-fauna,there were 36 faunal groups which belonged to 32 families and 8 orders.The dominant group was Formicidae with 22 common groups accounting for 93.33% of the total,and with 13 rare groups accounting for 6.67% of the total.It was shown that there was a significantly lower abundance,group richness and diversity of soil macro-faunal community in mobile sand land than in other four habitats(P0.05),while no significant differences(P0.05) were found in soil faunal abundance,group richness and diversity between semi-mobile sand land,semi-fixed sand land,fixed sand land and inter-dune land.In addition,fixed sand land had the highest biomass amongst the five habitats(P0.05),while there were no significant differences(P0.05) in soil faunal biomass between mobile sand land,semi-mobile sand land,semi-fixed sand land and inter-dune land.Based on soil faunal abundance and biomass,results of NMDS analysis confirmed that there were strong differences between mobile sand land and other four habitats including semi-mobile sand land,semi-fixed sand land,fixed sand land and inter-dune land,which indicated that there was a significant influence of severe desertification on soil faunal diversity.The changes in soil organic carbon,soil pH,and soil water content among these habitats were the main factors determining the distribution and growth of soil macro-fauna.For example,Tenebrionidae larvae tended to live in the soil conditions with rich organic carbon such as fixed sand land,where there were more individuals of Tenebrionidae larvae with higher biomass.These results suggest that the soil faunal biomass is closely correlated with the characteristics of biological individuals from soil faunal community in desertification,and some faunal groups have already adapted to different desertification environment and take a suitable survival way in each habitat.Fixed sand land having higher density,group richness and biomass of soil macro-fauna is a better habitat for soil fauna living,in comparison to semi-mobile sand land,semi-fixed sand land and inter-dune land.There also are negative responses of soil faunal diversity to desertification development in sandy grassland.So it is very evitable to take measures for desertification control to increase soil faunal and biological diversity,which in turn is beneficial for the fixation of mobile sand land and restoration of ecosystem in sandy habitats.