退化高寒草原土壤微生物变化特性研究

Study on the Variation Characteristics of Soil Microbial Biomass in the Degraded Alpine Steppes

对藏北退化高寒草原土壤微生物群落数量的研究结果表明:①相对于正常草地,轻度退化草地土壤细菌、放线菌、真菌数量均呈不同程度的提高;中度退化和严重退化草地土壤细菌和真菌数量则呈显著下降趋势,而土壤放线菌数量显著升高。②土壤真菌与土壤细菌表现为极显著正相关(P≤0.01);而与放线菌则为负相关;土壤放线菌和土壤细菌间则为显著负相关(P≤0.05)。③土壤细菌、放线菌和真菌与土壤有机质均呈显著相关,r值分别为0.7256、-0.7533、0.7215。④不同退化程度高寒草地土壤微生物数量以细菌占绝对优势,放线菌和真菌较少,并有不同的变动规律。⑤西藏高原高寒、干旱条件下,轻度退化草地一定程度的沙化所导致的土壤通透性能的改善对土壤微生物的繁殖与活动具有重要的促进作用。

The paper described the quantitative variation of soil microorganisms in northern degraded alpine steppes. The results showed that. ①the numbers of bacteria, actinomycetes and fungi in light degraded grassland soil increased in some degree than those in the normal grassland; but the numbers of bacteria and fungi in medium degraded and severely degraded grassland′s soil had the decreased tendency than the normal grassland, while the amount of myconhizal of both grassland′s soil significantly increased compared with those in the normal grassland soil. ②There is a significant pos correlation between fungi and bacteria （P≤0.01） ; but a negative one with actinomycetes, and a itive slgnificant negative correlation between actinomycetes and bacteria （P≤0.05）. ③The content of soil organic matter has significant correlation with soil bacteria, fungi and actinomycetes, with R of 0. 7256,-0. 7533, 0. 7215, respectively. ④The number of bacteria is the biggest one of the soil microbial biomass in differently degraded alpine steppes grassland. The numbers of actinomycetes and fungi were less obviously than that of bacteria, and they had their own changing rule.⑤The some degree desertification of light degraded grassland promoted soil′s aeration under the high and cold and dry conditions of Tibet plateau, and which has important improvement on the reproduction and function of soil microorganisms.