Soil Microbes and the Chemical Properties of the Rhizosphere and Non-Rhizosphere Soil under Two Types of Vegetation Restoration in the Hobq Sandy Land of Inner Mongolia, China

Two widely-distributed and efficient sand-fixing shrubs in the Hobq Sandy Land,Artemisia ordosica and Caragana intermedia,have received considerable attention related to their role in the process of vegetation restoration. This paper addresses the natural restoration of A. ordosica and the reintroduction of C. intermedia in the Hobq Sandy Land,begun in 1995. Variations in the soil microorganisms and chemical properties of the rhizosphere and non-rhizosphere soils were compared in areas restored with either A. ordosica or C. intermedia. This was carried out using field investigations,indoor biochemical experiments,and statistical methods. The measured variables included the total abundance of microorganisms,the abundance of soil bacteria,fungi,and actinomycetes,the amounts of C and N in the microbial biomass and measures of soil organic matter,soil p H,total nitrogen,total phosphorus,available nitrogen,available phosphorus,and available potassium. The relationship between soil microorganisms in the rhizosphere and soil chemical properties was also studied.Meanwhile,a synthetic index method was used to evaluate the effects of these two plant species on the recovery of the soil ecosystem,with the goal of providing scientific evidence to support vegetation restoration and redevelopment in the Hobq Sandy Land. Untreated sandy land subject to natural moving sand conditions was used as a control. The main findings were as follows:( 1) compared to untreated sandy land,vegetation restoration resulted in varying increases in both the soil microbe abundance and microbial biomass of both the rhizosphere and non-rhizosphere soil of the two types of vegetation restoration analyzed here. Among these variables,the total numbers of microorganisms and bacteria,as well as the quantities of C and N in the microbial biomass of the rhizosphere,were higher in sites restored with A. ordosica than in sites with C. intermedia. In addition,the numbers of fungi and actinomycetes in the rhizosphere of sites restored with C.intermedia were higher than that of sites with A. ordosica; this shows that the rhizosphere environment in areas with naturally restored A. ordosica is more conducive to increases in microbial activity than areas with reintroduced C. intermedia.( 2) The soil organic matter,soil total nitrogen,total phosphorus,available nitrogen,and available potassium content of both the rhizosphere and non-rhizosphere soil under these two types of vegetation restoration were higher