林分密度对马尾松林下土壤养分及酶活性的影响

以退化马尾松林下土壤为对象，通过调查我国红壤丘陵区典型林分密度的马尾松人工林，研究林分密度对土壤养分和土壤酶活性的影响。3种林分密度中，1 560株/hm2 左右中等林分密度的马尾松土壤有机质、全氮、全钾、速效钾、全磷、交换性钙和交换性镁等较高，但土壤酸化也较严重；同时，1 560株/hm2 左右马尾松林的土壤转化酶活性、脲酶活性和多酚氧化酶活性均较高，但过氧化氢酶活性表现最低；林分密度对马尾松土壤酸性磷酸酶活性影响不明显。因此，适宜林分密度的马尾松人工林一定程度上可改善该区林下土壤肥力及生化强度。

Effects of stand density on soil nutrients and enzyme activities in Pinus massoniana plantation

The effects of stand density on soil nutrients and enzyme activities were studied through investigating typical plots of Pinus massoniana plantation in the hilly red soil region in southern China. Pinus massoniana plantation of middle stand density (1 560 tree/hm2) had higher levels of soil organic matter, total nitrogen, total potassium, exchangeable calcium and exchangeable magnesium but with the most serious soil acidification phenomenon. At the same time, also had higher soil invertase, urease and polyphenoloxidase activities in Pinus massoniana plantation of 1 560 tree/hm2. But soil catalase activity was lowest in the Pinus massoniana plantation of middle stand density. Soil acid phosphatase activity did not respond obviously to the variation of stand density. Therefore, Pinus massoniana plantation with appropriate stand density can improve soil fertility and soil enzyme activities to some extent in the study region.