鼎湖山针阔叶混交林土壤酸度与土壤养分的季节动态

研究了鼎湖山南亚热带森林演替系列中处于中间阶段的针阔叶混交林土壤的pH值、水解氮、速效磷、钾、交换性钙、镁等几种营养元素的含量现状及季节动态。结果表明：混交林土壤为强酸性土壤，表层(0--20cm)土壤酸度高于中(20--40cm)、下(40-60cm)层土壤，0～40cm土壤pH值具有明显的季节波动性。降雨、温度、凋落物、植物根系以及微生物的活动等因素可能是鼎湖山混交林土壤pH值季节动态变化的主要因素。除Ca外，在同一剖面内，表层土壤养分的含量明显高于中下层，而中下层之间相差不大，养分大多在冬季较高，随着季节变动(1，4，7，10月)呈下降趋势。

Seasonal dynamics of soil acidity and nutrient contents under coniferous and broad-leaved mixed forest at Dinghushan

Soil acidity and contents of several nutrients, Hydrolysable N, available P, K, exchangeable Ca, Mg, and their seasonal dynamic changes in the Coniferous and broad-leaved mixed forest of Dinghushan were investigated. We found that the pH values of all soil layers in the Coniferous and broad-leaved mixed forest at Dinghushan were below 4.5, and increased with soil depth. Soil acidity in the 0~40 cm layer had an obvious seasonal fluctuated. The reason for these phenomena was probably the co-operation of the precipitation, temperature, litter fall and soil microbes. Soil nutrients were the highest in the surface horizon, and decreased with depth except exchangeable Ca. In January and April, contents of the most soil nutrients were higher than in July and October. K