青海三江源地区风沙土养分及微生物区系

采用常规方法研究了青海三江源地区风沙土的养分状况及微生物区系.结果表明，从流动、半固定风沙土到固定风沙土的演化过程中，土壤有机质含量明显增加，固定风沙土的有机质含量分别为流动和半固定风沙土的5.9和3.8倍；土壤氮素和磷素含量的变化趋势与有机质基本一致，均呈递增趋势；土壤钾素含量和土壤pH无明显变化规律.随着植被发育、流沙固定及土壤养分状况改善，风沙土中的微生物数量和区系组成也发生了显著变化.固定和半固定风沙土中的细菌、真菌及放线菌数量均明显高于流动风沙土，其细菌数量分别约为流动风沙土的4.0和2.8倍，真菌数量分别约为19.6和6.3倍，放线菌数量分别约为12.4和2.6倍；真菌种类数明显增加，放线菌区系组成也变得复杂.即随着风沙土由流动变为固定，土壤微生物生态系统中微生物的生物多样性增强，微生物组成趋于多样化.风沙土中的微生物数量与土壤有机质、全氮、速效氮及速效磷含量显著或极显著相关，与土壤全磷、全钾、速效钾含量及土壤pH之间相关性未达显著水平.

Nutrient contents and microbial populations of aeolian sandy soil in Sanjiangyuan region of Qinghai Province

Sanjiangyuan region(the headstream of three rivers)in Qinghai Province of China is the highest and largest inland alpine wetland in the world.The study on the nutrient contents and microbial populations of aeolian sandy soils in this region showed that soil organic matter content increased with the evolution of aeolian sand dunes from un-stabilized to stabilized state,being 5.9 and 3.8 times higher in stabilized sand dune than in mobile and semi-stabilized sand dunes,respectively.Soil nitrogen and phosphorus contents increased in line with the amount of organic matter,while potassium content and pH value varied slightly.The microbial populations changed markedly with the development of vegetation,fixing of mobile sand,and increase of soil nutrients.The quantities of soil bacteria,fungi and actinomycetes were 4.0 and 2.8 times,19.6 and 6.3 times,and 12.4 and 2.6 times higher in stabilized and semi-stabilized sand dunes than in mobile sand dune,respectively,indicating that soil microbial bio-diversity was increased with the evolution of aeolian sand dunes from mobile to stabilized state.In addition,the quantities of soil microbes were closely correlated with the contents of soil organic matter,total nitrogen,and available nitrogen and phosphorus,but not correlated with soil total phosphorus,total and available potassium,or pH value.