Study On Community Structure Of Soil Mites In The Rocky Desertification Areas Without And With Ecological Management

South China Karst area is the most concentrated area of karst in the world,and rocky desertification is a kind of ecological environment problems,which is worst in South China Karst area,caused by irrational use of biological resources by human activities.The ecological management of rocky desertification made it to a good development direction.Rocky desertification and environment changes caused by rocky desertification ecological management both have influence to community structure of soil mites.The research studied the changes of soil mite community,discussed the differences community structures of soil mites in different desertification areas,based on the background of three habitats including rocky desertification environment,the initial environment of rocky desertification ecological management and karst native forests.To reveal the laws of soil mites with environmental evolution of rocky desertification,recognizes the composition and characteristics of soil mite community structure in rocky desertification areas,provides a basis for optimizing the ecological control measures of rocky desertification from the perspective of soil mite diversity protection.Therefore,this paper chosed a comparatively typical demonstration area of comprehensive management of karst rocky desertification,which is the study area of the Chaoying small watershed of the Salaxi demonstration zone in Qixingguan District,Bijie City,Guizhou Province.To study soil mites community structures of non-rocky desertification(forest),different levels of rocky desertification and different levels of rocky desertification ecological restoration form the aspects of mites composition and distribution,community diversity,community similarity,community structures of predatory mites,community structures of Oribatid and community dynamics,drawing the following main conclusions.1.The soil mites of families and genus in secondary quercus shrubs and Quercus variabilis forests are not exactly the same under native environment.Oppiella is a dominant genus of secondary shrubs,Parholaspulus?Scheloribates?Haplozetes are dominant genus of Quercus variabilis forests.There are high genus,number of individuals and individual density in Quercus variabilis forests,and they are significantly through seasonal changes.And,there are high diversity of mites in secondary quercus shrubs,high richness of mites in Quercus variabilis forests.The Oribatid ecological groups are mainly O type and P type.2.Although soil mites in potential,mild,moderate and severe rocky desertification environments have different families and genus,the families of the mild,moderate and severe rocky desertification environments reduced compared with non-rocky desertification.Ledermuelleria?Tectocepheus?Scheloribates?Trichogalumna are dominant genus of potential rocky desertification shrubs environment,Parholaspulus ? Perlohmannia ? Tectocepheus are dominant genus of potential rocky desertification corn fields,Scheloribates is dominant genus of moderate rocky desertification,Nothrus and Trichogalumna are dominant genus of severe rocky desertification.But individual density and quantity decreased gradually through deepening of rocky desertification except severe rocky desertification environment.And,soil mites show the inverse distribution in moderate and severe rocky desertification environments,the diversity and richness generally decreasing with the deepening of rocky desertification degree.Oribatid mites mainly O and P types,but M,G and MG types exist at the same time,In the rocky desertification environment,there are many species of Oribatid mites different from non-rocky desertification.The number of individuals and individual density of other environments are more than non-rocky desertification except moderate rocky desertification environment.3.Species composition and community structure of soil mites in different vegetation management modes under different degrees of rocky desertification are different.Walnut+grassland model with more families and genus,the number of groups and individual density decreased with the order of ecological restoration of potential,mild,moderate and severe rocky desertification,the number of individuals is relatively high in areas with mild rocky desertification.Nenteria,Parholaspulus,Nothrus,Geolaelaps,Tectocepheus and Trichogalumna are dominant genus of walnut-grassland,Haplozetes and Vilhenabates are dominant genus of walnut-prickly pear-grassland model.In addition,the number of Mesostigmatic mites genera increased and the number of Oribatid mites genera decreased compared with the non-rocky desertification.The number of genera increased in the management of the potential and moderate rocky desertification,both the number of individuals and the individual density increased in varying degrees except the management of potential rocky desertification.At the same time,the Oribatid mites ecological groups more complicated in the management model of walnut-grassland,but walnut-prickly pear-grassland management model is conducived to recovery the number of individuals of Macropyline and Poronota groups.4.In same vegetation types(walnut-grassland)under different degrees of rocky desertification,there are more genera,individual density and higher community diversity in potential restoration of rocky desertification area,higher the number of individuals in mild restoration rocky desertification area.It shows that the mode has different effects in different management levels of rocky desertification.5.Most of the soil mite community structure are not similar,very dissimilar or medium dissimilar between rocky desertification and non-rocky desertification,between different levels of rocky desertification,between different control models,between different levels of rocky desertification and its control model,showing that environmental changes affect the community structure of soil mites,also indicating the heterogeneity of the area environment is strong.6.Predator mite community structures show that the soil mites are dominated by r-selected in the majority of the study environment to breeding competition strategy,showed that soil environment in the study area is not stable,the ecological management also need to be further strengthened and optimized.7.Some dominant taxa such as Oppiella,Parholaspulus,Scheloribates,Haplozetes,Ledermuelleria,Nothrus,Tectocepheus and Trichogalumna were selected as preliminary indicators for the different degrees of rocky desertification in the study area,these indicator groups make a significant difference with their indicator groups of beech,pine,birch and Alnus japonica in foreign.Based on the complexity of the karst environment,the use of soil mites to indicate different degrees of rocky desertification environments needs further study.In conclusion,rocky desertification has affected species composition,the number of individuals,individual density and vertical distribution of mites.The initial management of rocky desertification ecology increased the diversity of soil mites,predatory mites take breeding competition strategy,higher Oribatid mite groups increased rapidly and the community structure tends to be complicated.