米槠天然林转变成杉木人工林后土壤可溶性有机碳的变化

对中亚热带米槠天然林及其采伐迹地形成的36年生杉木人工林0～20cm层土壤可溶性有机碳（DOC，dissolved organic carbon）含量进行研究，分析米槠天然林改造成杉木人工林后土壤DOC平均含量及其季节的变化情况．结果表明：米槠天然林0—20cm层土壤DOC平均含量为60．79mg·kg^-1，比杉木人工林（41．24mg·kg^-1）高47．41％；2个林分0～10cm、10～20cm层土壤DOC平均含量差异明显（P〈0．05），且都是0—10cm层大于10～20cm层；米槠天然林和杉木人工林土壤DOC含量在季节变化中都表现为秋季最大、冬季最小，但是两者的季节变化模式不完全一致；米槠天然林和杉木人工林土壤DOC的差异和人为干扰因素有关．

Changes of Soil Dissolved Organic Carbon after Converting Natural Castanopsis carlesis Forest into Cunninghamia lanceolata Plantation in Subtropical China

In order to estimate the influence of forest conversion on soil dissolved organic carbon （ DOC）, DOC contents and their seasonal dynamics in soil depths of 0-20 cm were studied in a natural Castanopsis carlesis forest and a 36-year-old plantation of Cunninghamia lanceolata formed on a de-forested land of natural Castanopsis carlesis forest in subtropical China. The results showed that the average content of soil DOC in 0-20 cm depth of natural Castanopsis carlesis forest was 60. 79 mg·kg-1 , 47.41% higher than that of the Cunninghamia lanceolata forest （41.24 mg·kg-1 ）. For each soil layer, there was significant difference in DOC content between the two forests （P 〈 0. 05 ）. Also, DOC content in the 0 - 10 cm layer was significantly higher than that in the 10-20 cm layer. Contents of DOC in different soil layers of both forests were highest in autumn and lowest in winter, but temporal change of DOC in study forests was not the same. The differences of soil DOC between natural and plantation forests may be related to human disturbance.