Abstract:

In order to explore the effects of land use patterns on Microorganism and enzyme activity in Karst small watershed soil, this thesis was aimed to provide the valuable references to optimize the structure of land uses and the comprehensive control of the rocky desertification. Utilizing the Karst of small watershed of Cheng-Jiang in Du'an County as research unit, this thesis analysed the effects of microorganism and enzyme activity on the surface layer of soil based on the different land uses in the watershed. The research showed that, the bacteria, which accounts for more than 85%, was in the large portion compared to the percentage of the line bacteria and fungus which were relatively in small amount under the various land use patterns. In the classification of the total amount, the grass land and soil micro-organisms were the largest which respectively contains 37.88×106 cfu/g and 26.70×106 cfu/g, followed by the natural woodlands, the scrub and the dry lands, whereas the retreat and plantation of cultivated lands are smallest which separately contains 8.78×106 cfu/g and 7.74×106 cfu/g. At the same time, in the investigation of the soil microbial diversity, the natural forest and plantation demonstrate the highest index which reads as 0.461 and 0.459, followed by the grass land, the scrub and the retreat farmland, and the dry land was the lowest which accounted for 0.155. Therefore, the soil microbial diversity was in inconsistency with the change trend of the total soil microbial. Under different land uses, there also existed the great differences in the surface enzymes, in which the transformation enzymes, the proteases, the catalase and the urease played the most active roles in the natural soils which read respectively as 0.195 mL/(g?min), 1.2 mL/(g ?min), 0.753 mL/(g?min) and 1.5 mL/(g?min), work as the least parts in the return lands and dry lands, and engage in the medium activities in the least parts, the bushes, the artificial woodland, the shrub land, the irrigation and the pasture.