围封对荒漠草原土壤微生物数量及其酶活性的影响

Effects of Enclosure on Soil Microbial Quantity and Enzyme Activity in Desert Steppe

以鄂尔多斯高原温性荒漠草原为对象，对比研究了放牧和围封条件对草原植物地下生物量、土壤有机质、土壤微生物数量及酶活性的影响，旨在为干旱区退化草地的恢复与重建提供科学依据。结果表明，（1）与放牧区相比，围封显著增加了表层土壤（0-10 cm）草地植物地下生物量23.81%，极显著增加了次表层土壤（10-20 cm）草地植物地下生物量37.21%，而对土壤有机质含量无显著影响。（2）围封极显著提高了表层土壤真菌种群数量71%，次表层土壤细菌种群数量147%，显著提高了底层土壤（20-40 cm）真菌164%和表层、次表层土壤放线菌种群数量56%和8.9%。（3）围封区的次表层土壤脲酶活性显著增加了31.13%，表层土壤蔗糖酶活性显著降低了24.14%，表层土壤过氧化氢酶和碱性磷酸酶活性分别显著提高了16.59%和11.76%。（4）围封与放牧条件下，各指标相关性表现不尽一致；放牧条件下，放线菌种群数量与各指标相关性均不显著（P〉0.05），而在围封下，放线菌与真菌种群数量及碱性磷酸酶活性无显著相关性（P〉0.05），与其他指标均表现出显著（P〈0.05）或极显著（P〈0.01）正相关关系，相关系数达68%以上；放牧条件下，真菌种群数量与4种土壤酶活性均呈极显著（P〈0.01）正相关关系，相关系数在84%以上，而围封条件下，其与4种酶活性均呈显著正相关关系（P〈0.05）。

This study conducted on aStipa breviflora dominated temperate desert steppe in Ordos plateaus, a comparative studied the impacts of grazing and enclosure on belowground standing biomass, soil organic matter, soil microbial quantity and enzyme activity. Objective of this study was to provide a scientific basis for the recovery and reconstruction of degraded grassland in arid areas. The key findings are, （1） Compared with the grazing area, enclosure significantly increased 23.81% and 37.21% grassland belowground standing biomass in the surface soil （0-10 cm） and in the subsurface soil （10-20 cm）, respectively, while it had no significant effect on soil organic matter content. （2） Enclosure significantly improved 71% fungi population in soil surface and 147% bacterial population in subsurface, and also significantly increased 164% fungi population in underlying soil layer （20-40 cm） and 56% and 8.9% actinomycetes population in soil surface and in subsurface, respectively. （3） Enclosure significantly increased 31.13% urease activity in the subsurface soil, decreased 24.14% sucrose activity in the surface soil, and improved 16.59% catalase activity and 11.76% alkaline phosphatase activity in the surface soil. And （4） it was not consistent of the correlation between enclosure and grazing on different indexes, showing that the actinomycetes population was no significant correlation among different indexes under grazing treatment （P〉0.05）, while with the exception of no significant correlation between actinomycetes and fungi population with alkaline phosphatase activity under the enclosure （P〉0.05）, the other indexes showed significant （P〈0.05） or very significant （P〈0.01） positive correlation relationship with more than 68% correlation coefficient. In addition, the fungi population had a very significantly （P〈0.01） positive correlation with four kinds of soil enzyme activity under the grazing condition, and the correlation coefficient is above 84%. And it was a significant positive correlation between the fungi population and four soil enzyme activity under the enclosure （P〈0.05）.