<正>采用样方法调查了岭南自然保护区常绿阔叶林中39种主要树种的重要值，利用Levins、shannon-Wiener生态位宽度公式测算了15种优势种群的生态位宽度、生态位相似性和生态位重叠。结果表明：群落中主要优势种群的生态位较大，木荷、檵木、甜储的Levins和Shannon-Wiener生态位宽度分别为0.9839、0.9148、0.8731和0.9926、0.9587、0.9279。生态位宽度较高的两个树种，其种间生态位相似比例值较高，木荷与檵木、甜槠生态位宽度较大树种间生态位相似性比例分别是0.8132、0.8131。生态位宽度较大的种群与其他种群间的生态位重叠较大，优势种群木荷与其他各种间的生态位重叠为0.2981～0.3631；生态位宽度较小的种群与其他种群间的生态重叠较小，生态位最小的青冈栎与其他树种的重叠值是0.0097～0.2800。

A field piot experiment was conducted to study phosphorus move down by leaching and its relation to the concentration of Olsen-P in surface soil on two types of paddy soils (the permeable paddy soil in the Anzhen site and the waterlogged paddy soil in the Changshu site) in the Taihu Lake region. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 30, 75, 150, 300 kg/hm2 applied P per season. The results showed that all the Dissolved P (DP) concentrations in leachate samples were much greater than the threshold of 0.02mg/L caused the eutrophication. Fertilizer P rate had an effect on P concentrations in the leachate. The dominant form of P in the Ieachate was the Particulate P (PP). The average value for PP/TP in the leachate from the various P treatments on the permeable paddy soil and the waterlogged paddy soil was 70.9% and 67.0%, respectively. Under the normal P application rate of 30 kg/hm2 each season, the P losses by leaching at 30cm depth in the Changshu site was 469.7g/hm2, and greater than 378.5g/hm2 in the Anzhen site. The change-point of phosphorus by leaching was 33.0 mg/kg in the permeable paddy, higher than in the waterlogged paddy soil (26.3 mg/kg). This difference was probably associated with the different contents of organic matter and soil clay particle of two paddy soils, and indicating that P loss by leaching in the waterlogged paddy soil would be easier than that in the permeable paddy soil.