Effects Of Thinning On Soil Enzyme Activities In Pinus Massoniana Lamb

In order to discuss the influences on soil enzyme activities of thinning, an experiment was conducted to study the urease in the soil of25years Pinus massoniana forest which was thinning by light (25%), moderate (45%) and high (65%) intensity six years ago in Lishui. The general results are given below:(1) Overall, thinning has an ascending function on soil enzyme activities, but the effects are variety in different thinning intensity. Light thinning intensity enhances invertase and hydrogen peroxide activities most in October, as well as alkaline phosphatase activity in December. The effects of moderate intensity is more obvious in the rest.(2) Soil enzyme activities shows an obvious law of diminishing along soil depth. The differences of soil enzyme activities between surface soil (0-10cm) and subsurface soil (10-20cm) have reached significant levels (P<0.05) excluding invertase and urease for individual months. In addition, we found that soil protease, alkaline phosphatase and hydrogen peroxide activities decrease more obvious along the soil depth under the moderate and high intensity thinning.(3) Soil enzyme activities show a clear dynamic law with the seasons change, thinning has a certain effect on the law. Thinning makes the trend with seasonal change of alkaline phosphatase and invertase activity more evident, make the trend of protease, urease and catalase abate.(4) Correlation analysis shows that there are significant (P<0.05) or highly significant (P <0.01) positive correlation in any two of urease. alkaline phosphatase and invertase. Soil catalase shows a highly significant positive correlation with urease and invertase, the protease shows a highly significant negative correlation with catalase and urease. Soil invertase. urease and catalase activities show positive correlations with soil temperature, with which protease activity shows highly significant negative correlation. Excluding the protease activity in surface soil, the correlation between all the other soil enzymes and soil organic matter content is not significant. The correlation between soil enzyme activities and soil moisture is not significant.