封育年限对伊犁绢蒿荒漠土壤微生物及酶活性的影响

目的]揭示封育条件下土壤微生物及其土壤酶活性的适应机制,为退化草地恢复提供科学依据。方法]采用蛇形布点法,采集封育0,3及11a伊犁绢蒿荒漠0—5,5—10,10—20cm土壤样品;采用常规方法对土壤有机质、过氧化氢酶活性、脲酶活性及土壤微生物数量进行测定。结果]随封育年限增加,0—5cm土层有机质含量呈增加趋势,且封育11a较对照显著提高14.2%。土壤微生物组成中细菌数量最多,占绝对优势,放线菌次之,真菌最少。0—5cm土层细菌、真菌数量随封育年限增加呈降低趋势,放线菌数量呈增加趋势,至封育11a细菌、真菌较对照依次显著降低(47.3%,25.5%),而放线菌则显著增加(15.5%);5—20cm土层细菌数量变化不显著,而放线菌及真菌数量多呈增加趋势。封育对伊犁绢蒿荒漠0—20cm土层过氧化氢酶活性影响不显著,而0—10cm土层脲酶活性随封育年限增加呈增加趋势,10—20cm土层则呈降低趋势。结论]长期封育有利于土壤有机质的积累,促进表层土壤放线菌数量及脲酶活性的增加。

Effects of Grazing Exclosure Years on Soil Microorganism and Enzyme Activities in Seriphidium Transiliense Desert

Objective] To explore the adaptive mechanisms of soil microorganism and soil enzyme activity under grazing exclosure conditions in order to provide scientific basis for the recovery of degraded pasture.Methods] Soil samples were collected from different soil layers (0-5 cm, 5-10 cm and 10-20 cm) in Seriphidium transiliense desert under different exclosure years (0 a, 3 a and 11 a) by zigzag sampling method. Then, the soil organic matter, catalase and urease activities, and the amount of soil microorganisms were measured by the conventional methods.Results] The organic matter content in 0-10 cm soil layer increased with the increasing exclosure years, and the soil organic matter content of 11-year enclosure was 14.2% higher than that of the control. In the composition of microorganism, the largest amount was bacteria, followed by actinomycetes, and fungi was the least. The amount of bacteria and actinomycetes in 0-5 cm soil layer decreased and the amount of fungi increased with the increase of exclosure years, and compared with the control, the amount of bacteria and fungi of 11-year exclosure were decreased by 47.3% and 25.5%, respectively, while the amount of actinomycetes increased by 15.5%(p<0.05). There was no significant difference in the amount of bacteria in the 5-20 cm soil layer among different exclosure years, but the amount of fungi and actinomycetes increased with the increase of exclosure years. There was no significant difference on catalase activity in 0-20 cm soil layer among different exclosure years in S. transiliense desert. The urease activity in 0-10 cm soil layer increased with the increase of enclosure years, and that was decreased in 10-20 cm soil layer.Conclusion] The long time enclosure is beneficial to the accumulation of soil organic matter, and can improve the amount of actinomycetes and urease activity in the topsoil.