珠江流域中游5种典型森林类型土壤理化特征比较

为探讨珠江流域中游广西苍梧地区森林生态系统物质循环、森林植被规划基础数据，研究了该区域5种典型森林类型土壤基本理化性质。结果表明:珠江流域苍梧地区5种森林类型土壤机械组成砂粒变幅在35.67%~40.53%；粘粒变幅在30.66%~35.45%；细粉粒变幅在22.4%~23.64%；粗粉粒变幅在5.24%~6.44%。对各森林类型土壤A层（0~15 cm）减去D层(45~60 cm)化学性质的比较，各森林土壤有机质和全N积累大小顺序为湿地松-木荷混交林>红锥林>大叶栎林>桉树林>马尾松林；土壤全磷积累大小顺序为红锥林>湿地松-木荷混交林>马尾松林>桉树林>大叶栎林；土壤全钾的消耗大小顺序为大叶栎林>桉树林>红锥林>湿地松木荷混交林>马尾松林。土壤粘粒及细粉粒与土壤有机质及全氮含量呈负相关关系，而砂粒与有机质和全氮呈正相关，与全钾和全磷呈负相关；粗粉粒与全磷、全钾呈正相关。综合而言，在珠江上游苍梧地区对于土壤保育方面，土壤机械组成并非越细越好，其粒径组成应介于粗粉粒和砂粒之间为宜。5种森林类型对土壤保育功能提高的影响大小顺序为湿地松-木荷混交林>红锥林>大叶栎林>马尾松林>桉树林。

Soil Physicochemical Properties of 5 Typic Forests in the Middle Reaches of Pearl River Basin

The soil basic physicochemical properties of 5 typical forests with different characteristics were researched in Cangwu region of Guangxi located in the middle reaches of the Pearl River, to provide basic data to further exploring material circulation of forest ecosystem and planning for forest vegetation in the area. The results indicated that for soil mechanical composition, the sand grain contents ranged from 35.67% to 40.53%; the clay content: 30.66%-35.45%; the fine silt content: 22.4%-23.64%; the coarse dust: 5.24%-6.44%. Soil organic matter and total N accumulation were in an order of Pinus elliottii and Schima superba mixed forest>Castanopsis hystrix>Quercus griffithii> Eucalyptus>P. massoniana; for the total P, the order was C. hystrix>P. elliottii and S. superba mixed forest>P. massoniana> Eucalyptus>Q. griffithii; and for the total K: Q. griffithii> Eucalyptus>C. hystrix>P. elliottii and S. superba mixed forest>P. massoniana. Significant negative correlations were found among the indices of soil clay and fine silt with organic matter and total N. Significant positive correlations were found among sand grain with organic matter and total N. The sand grain with organic matter and total N had positive correlations, but for the total K and P negative correlations were observed. Significant positive correlations were found among coarse dust with total K and P. To sum up, from the view of soil conservation, it is preferable that the particle size composition should be between coarse silt and sand. The contribution of 5 different forests on soil conservation improvement was P. elliottii and S. superba mixed forest>C. hystrix>Q. griffithii>P. massoniana> eucalyptus.