Study On The Spatial-temporal Dynamic Of Meso-micro Soil Fauna Communities And Its Influencing Factors In Baotianman Nature Reserve

As an important part of the terrestrial ecosystem,soil animals play an important role in the material cycle and energy flow of the ecosystem.At the same time,as a kind of integrated and stable group in the ecosystem,soil animals are more sensitive to the environment and are important indicative factors of environmental change.Baotianman Nature Reserve,located in the North-South Transition Zone of China,is a typical ecosystem sensitive area.Baotianman National Nature Reserve was selected as the study area to understand the characteristics of meso-micro soil fauna community in the North-South Transition Zone of China.In our study,Soil fauna were sampled at 16 plots set up between altitude 900-1700 m along the north and south slopes in spring and autumn respectively.The samples were separated and identified by Tullgren method.The temporal and spatial variation of meso-micro soil fauna community in Baotianman was analyzed by using statistical analysis method,and the correlation between meso-micro soil fauna community and soil environmental factors was revealed by using redundancy analysis method.This study can provide theoretical reference for species diversity conservation in the nature reserve and species diversity maintenance in the North-South Transition Zone under the background of global change,and also can provide basic information for the establishment of soil animal database and information system in the Transitional Zone.The main conclusions are as follows:(1)There are 52 kinds of meso-micro soil fauna captured in Baotianman Nature Reserve,among which 13063 individuals,Oribatida,Actinedida and Isotomidae are the dominant species,which account for 65.31% of the total captured soil animals,and there are 12 common species,which account for 27.31%of the total captured animals,including Gamasida,Hypogastruridae,Entomobryidae,Sminthuridae,Cyphoderidae,Onychiuridae and Formicidae.In addition,there were 37 rare species,and the number of individuals accounted for only 7.38% of the total captured.(2)In the horizontal distribution,6305 individuals of 49 species were captured on the south slope,and6758 individuals of 44 species were captured on the north slope.The total number of individuals on the south slope is smaller than that on the north slope,while the total number of species is larger than that onthe north slope.The seasonal dynamic research showed that the total number of individuals and groups in autumn is greater than that in spring.In the vertical distribution,the number of individual and group in the southern and northern slopes show the characteristics of "surface aggregation",and the distribution of the number of individual and group in different soil layers is as follows: layer O > layer A > layer B > layer C.The distribution characteristics of the individual and group of soil animals in spring and autumn are also obvious,and the intensity of "surface aggregation" in autumn is greater than that in spring.(3)Species richness index(M)of south slope presents "W" type distribution with altitude increasing,while that of north slope presents "M" type distribution.Species diversity indexes(H')of south slope are higher in the middle altitude gradient(1150m,1250 m,1350m)than that of north slope.The evenness index(E)and dominance index(C)of soil animals were not significantly affected by slope and altitude(P > 0.05).The richness index(M)and diversity index(H')of meso-micro soil fauna were significantly affected by slope and altitude.In addition,the difference of evenness index(E)and dominance index(C)between spring and autumn was not significant(P > 0.05).(4)The results of Sorensen similarity analysis showed that the meso-micro soil fauna in the 16 sample plots reached above the medium level of similarity.The Sorensen similarity index in the south slope is between 0.70 and 0.89,and in the north slope is between 0.78 and 0.91,and the communities of soil microfauna in the north slope all reach significant similarity level.In addition,the similarity on the south slope is lower than that on the north slope.The seasonal dynamic study shows that the similarity index in spring and autumn is also above the medium similarity level,but the variation range in spring(0.68-0.95)is larger than that in Autumn(0.70-0.89).As a whole,the larger the altitude interval is,the lower the similarity of meso-micro soil fauna in the sample is.(5)Redundancy Analysis of the main groups of meso-micro soil fauna showed that the distribution of meso-micro soil fauna was significantly affected by soil water content,p H value and organic matter in spring,and the significant correlation between soil water content,bulk density,p H value,organic matter,total phosphorus,total nitrogen and meso-micro soil fauna in autumn was the important influence factors.