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采用熏蒸-提取法、Biolog微平板培养法,研究了定西典型人工乔木林、人工灌木林、农田、撂荒地、天然草地等植被类型下0～20cm土层土壤微生物生物量和土壤微生物群落代谢多样性,并通过通径分析的方法解释了土壤微生物与土壤养分的关系,从土壤微生物的角度对当地典型植被类型做出了评价.结果表明:相对于耕作而言,退耕还林(草)对恢复土壤微生物资源具有积极意义;研究区垄坡荒地、撂荒地和油松林的土壤微生物生物量碳较高,其次为柠条林、苜蓿地、侧柏-山杏和道沿荒地,以小麦和马铃薯农田较低;研究区垄坡荒地、撂荒地、油松林、柠条林和苜蓿地的土壤微生物生物量氮较高,小麦和马铃薯农田较低;具有根瘤固氮菌的植被(柠条和苜蓿)的土壤微生物生物量氮占全氮的比例最高;农田由于长期生物量损耗且补充不足,其土壤微生物的储量和活性均很低,而通过种植人工乔木林、灌木林或弃耕撂荒,土壤微生物数量和活性能恢复到天然草地的水平,且效果随恢复年限的增加而更显著;柠条灌木林通过20a的恢复,其地下微生物数量与50a林龄的油松林相近,其微生物活性和土壤养分利用效率甚至超过了油松林.综合考虑不同立地条件下植被的土壤微生物特性,认为豆科灌木(如柠条)是恢复植被的较好选择.
The soil microbial biomass and soil microbial community metabolism in 0-20 cm soil layer of Dingxi typical artificial tree forest, artificial shrub forest, farmland, fallow land and natural grassland were studied by fumigation-extraction method and Biolog microplate culture method. The relationship between soil microbes and soil nutrients was explained by the method of path analysis, and the typical local vegetation types were evaluated from the perspective of soil microorganism.The results showed that compared with tillage, The restoration of soil microbial resources is of positive significance. The soil microbial biomass carbon in the ridge land, abandoned land and Pinus tabulaeformis forest is higher, followed by Caragana korshinskii, alfalfa land, arborvitae-apricot land and roadside wasteland, Potato farmland was low. Soil microbial biomass nitrogen was higher in the fields of ridge wasteland, fallow land, Pinus tabulaeformis, Caragana korshinskii and alfalfa, and lower in wheat and potato fields. Nitrogen-fixing plants (Caragana korshinskii and alfalfa ) Had the highest proportion of total microbial biomass N in total nitrogen. Due to the long-term biomass depletion and insufficient replenishment, the quantity and activity of soil micro-organism in farmland were very low, By planting artificial arbor, shrubbery or abandonment fallow, the quantity and activity of soil microorganism returned to the level of natural grassland, and the effect was more significant with the increase of the restoration years. When Caragana korshinskii was restored by 20a, the number of underground microbes Compared with Pinus tabulaeformis forest of 50 years old, its microbial activity and soil nutrient use efficiency even surpassed that of Pinus tabulaeformis forest.Considering the characteristics of soil microorganisms in different habitats, it is considered that leguminous shrubs such as Caragana korshinskii select.