不同扰动高寒草地土壤微生物数量时空变化特征

为揭示东祁连山高寒草地不同扰动生境中土壤三大类微生物和氮素生理群数量的时空变化特征,采用2003年、2011年和2017年在相同样地(一年生、多年生、围栏内和围栏外草地)、相同研究方法(平板菌落计数)对草地土壤三大类微生物(真菌、细菌和放线菌)数量和氮素生理群(硝化细菌、反硝化细菌、好气性固氮菌和嫌气性固氮菌)数量进行时空动态比较。结果表明:(1)在相同时间、不同扰动生境中土壤三大类微生物和氮素生理群数量变化差异显著(p0.05),均随着土层的加深而逐渐减少,具有明显的垂直分布规律;(2)在不同时间、不同扰动生境中,土壤三大类微生物和氮素生理群数量变化差异显著(p0.05),土壤细菌、放线菌、硝化细菌和好气性固氮菌数量分布为2003年2011年2017年;真菌、反硝化细菌和嫌气性固氮菌数量分布为2017年2011年2003年;(3)不同扰动生境中微生物总数量变化表现为2003年2011年2017年。2011年、2017年的微生物总数量与2003年相比较,一年生草地分别下降了1.65,2.86倍,多年生草地分别下降了3.12,5.12倍,围栏内草地分别下降了3.05,4.09倍,围栏外草地分别下降了2.11,3.26倍。综上,随着不合理放牧和人为利用方式,东祁连山高寒草地土壤微生物数量随时间变化逐渐减少,为此应对该地区草地的利用和保护给予足够的重视。

Spatial-temporal Variation of Soil Microorganism Quantity in Different Perturbed Alpine Meadows

In order to reveal the spatial and temporal variations of soil microbes in alpine grassland in Eastern Qilian Mountains, three species of grassland soil microbes (fungi, bacteria and antinomycete) were collected from the same study area (perennial cultivated grassland, inside the fence grassland, annual cultivated grassland and outside the fence grassland) in 2003, 2011 and 2017 usingplatelet count method. The results showed that:(1)At the same time, three types of soil microbes and nitrogen physiological populations were significant (p<0.05) in different disturbance habitats, and they decreased gradually with the increase of the soil depth; (2)In different time and different disturbance habitats, three types of soil microorganisms and the number of nitrogen physiological groups were significant (p<0.05; specifically, the ranks of soil bacteria, actinomycetes, nitrifying bacteria and aerobic nitrogen fixing bacteria distribution were 2003 > 2011 > 2017; and the ranks of fungi, denitrifying bacteria and anaerobic nitrogen fixing bacteria quantity distribution were 2017 > 2011 > 2003; (3) The total number of microorganisms in different disturbance habitat performance were 2003 > 2011 > 2017. Compared with 2003, the total number of microbes in 2011 and 2017 decreased by 1.65 and 2.86 times. The perennial grassland decreased by 3.12 and 5.12 times respectively, the grassland within the enclosure decreased by 3.05 and 4.09 times, and the grassland decreased by 2.11 and 3.26 times respectively. In conclusion, with the unreasonable grazing and artificial utilization, the number of soil microorganisms in the alpine grassland of East Qilian Mountains gradually decreased with time. Therefore, we should pay enough attention to grassland utilization and protection in this area.