库布齐沙地两种植被恢复类型根际土壤微生物和土壤化学性质比较研究

油蒿(Artemisia ordosica)与中间锦鸡儿(Caragana intermedia)是库布齐沙地分布广泛的优良固沙植被类型,在植被恢复过程中受到关注。以库布齐沙地自然恢复的油蒿群落与人工种植的中间锦鸡儿群落为研究对象,以流动沙地为对照,采用野外调查、室内生化实验与统计分析相结合的方法,分析两种植被恢复类型根际与非根际土壤微生物、土壤化学性质的差异,研究土壤微生物与土壤化学性质间的相关关系,并运用综合指数法评价两种植被恢复类型对土壤生态系统的恢复效果,为库布齐沙地植被恢复与重建提供科学依据。主要结论如下:(1)与流沙对照相比,两种植被恢复类型根际、非根际土壤微生物数量、微生物生物量碳、氮含量均有不同程度的提高,其中,自然恢复的油蒿群落根际土壤微生物总数、细菌数量、微生物量碳和氮含量均显著高于中间锦鸡儿根际,真菌和放线菌数量分布表现为中间锦鸡儿油蒿;(2)两种植被恢复类型根际、非根际土壤有机质、全氮、全磷、速效氮、速效钾含量均比流动沙地有不同程度地提高,其中,油蒿根际、非根际土壤有机质、全氮、速效氮含量显著高于中间锦鸡儿;(3)影响油蒿和中间锦鸡儿群落土壤微生物数量、生物量碳和氮的土壤因子是有机质、p H值、全氮、速效氮、速效钾、速效磷,其中,对两种植被恢复类型土壤微生物数量和生物量有正向促进作用的主要因子是土壤有机质、速效钾和全氮含量;(4)运用综合指数法计算出基于14个土壤指标的土壤质量综合指数(SQI),SQI值排序为:油蒿根际中间锦鸡儿根际油蒿非根际中间锦鸡儿非根际流沙对照。自然恢复的油蒿群落对土壤质量的改良效果显著优于人工种植的中间锦鸡儿群落,是库布齐沙地生态恢复的适合途径之一。

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 pH, 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 withC. 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 than in untreated sandy land. Among the soil conditions, the soil organic matter, soil total nitrogen, and available nitrogen content of both the rhizosphere and non-rhizosphere soil were higher in sites with A.ordosica than in those with C. intermedia, showing that the soil nutrient enrichment was significantly higher at sites restored with A. ordosica. (3) The soil factors that affect the quantity of soil microbes present, as well as amounts of C and N in the microbial biomass of areas restored with A. ordosica and C. intermedia, include soil organic matter, pH, total nitrogen, available nitrogen, available potassium, and available phosphorus. Among these, soil organic matter, total nitrogen, and available potassium had a positive effect on the quantities of soil microbes as well as the amounts of C and N in the microbial biomass under the two types of vegetation restoration analyzed here. (4) The synthetic index method was used to calculate a soil quality index that was based on 14 soil quality indices; the order of the values of the soil quality indices was as follows:rhizosphere soil of A. ordosica > rhizosphere soil of C. intermedia > non-rhizosphere soil of A. ordosica > non-rhizosphere soil of C. intermedia > soil of untreated sandy land. The results confirm that the effects of the A. ordosica community on the soil during natural restoration were better for soil improvement than those of the C. intermedia community, making the A. ordosica community more appropriate for use in the ecological restoration of the Hobq Sandy Land.