Community Structure Of Soil Fauna And Its Seasonal Dynamic Of Jujube Forest In Northern Region Of Shaanxi

Research about soil fauna at jujube forest in Northern area of Shaanxi has not been reported. With a comprehensive review on research advance of community structure of soil fauna and its seasonal dynamic in domestic and overseas, it is the first time to research the community structure of soil fauna and its seasonal dynamic of jujube forest in Northern region of Shaanxi, which has revealed structural characteristics of soil fauna community which is as an important group of decomposers. The research also discussed the internal relationship of environment and soil fauna which are as stable environmental indicator factors. They have great practical guiding significance for jujube forest health and ecological regulation and management of pests. Furthermore, they can provide basic data and theoretical basis for further study on indicative function of soil fauna's effect on soil quality changes.In the study area of jujube forest in Northern region of Shaanxi, a systematic study on relationship of the soil fauna community characteristics and soil physicochemical factors and seasonal dynamic and so on was done ,which took the soil fauna and the rhizosphere soil as the objects of study and was based on the combining research methods of field investigation sampling, fixed point dynamic observation and laboratory experiment tests, at 4 sample points and 7 plots in Yan' an Wanhua Mountain, Yanchuan County, Qingjian County, Jia County in March, June, September and November in the year 2007.Synthesizing all the results, we draw the following conclusions:1. It is the first time to research soil fauna community which fills the blank of study on soil fauna in Northern area of Shaanxi. The dominant groups and common groups of soil fauna in jujube forest of Northern region of Shaanxi are mostly micro-soil-insects with a large quantity, which are the fundamental component of soil fauna in jujube forest. The vertical distribution of soil fauna diversity of jujube forest in Northern region of Shaanxi appears visible difference of underground vertical structure. The distribution of soil fauna in soil is of surface aggregation. Furthermore, surface aggregation of individual quantity is stronger than of group quantity. The analysis which is about diversity important indexes of soil fauna in different soil layers of jujube forest shows that the succession of four seasons influence on composition, quantity and diversity of soil fauna community. Moreover, with the succession of four seasons the habitat of soil fauna changes gradually, which causes seasonal variation of vertical distribution of soil fauna. The seasonal change of diversity of soil fauna community of jujube forest in Northern area of Shaanxi: autumn >summer >spring >winter. The soil fauna seasonal groups of jujube forest in Northern area of Shaanxi have spatial distribution, and some of them which have large quantity have significant dominance. Additionally, with little change of the groups number in four seasons, quantity plays an important role in indexes which deciding the diversity of soil a fauna in seasons. The composition of soil fauna groups of jujube forest in Northern area of Shaanxi has low heterogeneity but relatively high or higher similarity coefficient.2. The soil fauna guilds can be divided into six function class groups which are herbivorous, predatory, saprophagous, debris - feeder's, fungivorous form and omnivorous soil fauna. A probe into internal relation between soil fauna and ecological regulation of harmful species, and the construction of complex pattern about ecological regulation and management of soil fauna guild and pest of jujube forest pest have been done.3. Researched the relationship between community structure of soil fauna in jujube forest and activity of soil enzymes for the first time and analysis their seasonal dynamics. The community structure of soil fauna of jujube in Northern region Shaanxi and activity characterization of soil enzyme show obviously seasonal dynamic. Protease and urease both have the closest relationship with soil animals.4. The relationship between community structure of soil fauna and soil physicochemical factors has been studied systematically. The temporal dynamics of soil fauna in jujube forest and soil factors also have been comprehensively analyzed. The degree of correlation between number of soil fauna groups of jujube in Northern area of Shaanxi and soil factors is not as clear as that between groups number and density. The number and density of macro-soil-fauna groups and the density of meso-micro soil fauna are closely related with the soil nutrition elements; and the influence of pH value either on soil animal group number or density is the most significant. Soil moisture has notable influence on groups of macro-soil fauna and density of meso-micro soil fauna. The features of soil fauna and soil environment elements have seasonal variation. The difference of habitats has extremely remarkable influence on macro-soil-fauna groups and number of groups while the change of season only impact significantly on diversity of meso- micro-soil fauna.5. Based on the character of the geomorphological types of jujube forest in Northern region of Shaanxi, they can be divided into 5 geomorphologic types which are loess gully, loess mound, loess liang, soil rock mountainous and yellow river canyon. The relationship among soil fauna community ecology and other geomorphologic types has been studied. Soil and geomorphologic types have important impact on soil fauna groups, individual number, abundance and diversity. The soil organic matter content is the main ecological factors which influence the community structure of soil fauna. They provide some relevant scientific basis for soil rational utilization, restoration and improvement of jujube forest in Northern area of Shaanxi.6. Based on the relationship between soil fauna and jujube forest ecosystem, the linking of soil animals in jujube forest with jujube forest health and ecological regulation of pests is proposed. Moreover, according to the principle of comprehensive defense and control of harmful species, the relevant controlling strategies and treatment methods have been worked out, and the ecological regulation system of pests in jujube forest has been preliminarily constructed. This research provides scientific basic data for ecological regulation of jujube health and pests. It has certain practical guiding significance as well. In the future the further study of relationship between soil fauna in jujube forest and jujube health and pests should be intensified.