【摘要】 在福建南平地区 ,对林龄和密度不同的两片杉木人工林的凋落物和森林降水化学进行了 3a(1994～1996 )的定位研究 .株密度n =2 370hm-2 的 16a生林分 (标记为FFC)和株密度n =1180hm-2 的 41a生林分 (标记为XQF)的年凋落量分别为 6 2 10 .7kghm-2 和 3 146 .2kghm-2 ,其中落叶分别占总重量的 76 %和 6 8% .凋落物中 5种主要营养元素的年归还量分别为 173.92kghm-2 和 84.2 0kghm-2 ,其数量大小顺序均为Ca >N >Mg >K>P ,并在 4月份和 11月份出现两次峰值 .在两监测样地 ,降水通过林冠后养分富集现象均十分明显 .降雨、穿透雨和树干径流中养分浓度呈现显著的季节变化 ,均以夏季最低 ,冬季最高 ,春秋季居中 ,这种格局强烈受降雨量的控制 .在两林分中降水引起的 5种元素的年淋溶量分别为 173 .33kghm-2 和 10 7.5 3kghm-2 ,大小顺序为K >Ca >Mg ,而N(及FFC的P)出现负值 ,表明其被林冠层直接吸收 .林龄和密度对生态系统的养分归还具有重要影响 .图 5表 4参 15更多还原

【Abstract】 Chemistry of litter and rain fall was monitored for three years (1994～1996) at two sites established in Chinese fir ( Cunninghamia lanceolata ) plantations with different stand ages and densities in Nanping, Fujian. The annual litter in 16-year-old stand of 2 370 stems per hm -2 (designated as FFC) and 41-year-old stand of 1 180 stems per hm 2 (designated as XQF) were 6 210.7 kg hm -2 and 3 146.2 kg hm -2 , with fallen leaves accounting for 76% and 68%, respectively. The quantities of five macronutrients transferred to forest floor by litterfall were 173.92 kg hm -2 and 84.20 kg hm -2 a -1 , respectively, decreasing in the order of Ca>N>Mg>K>P, which exhibited two peaks in April and November. Rainfall was significantly enriched through forest canopies in the both sites. Nutrient concentrations in rainfall, throughfall and stemflow exhibited strong seasonal patterns, consistently with minimal values in summer months, intermediate in spring and fall, and maximal in winter, which appeared to be affected greatly by precipitation amount. Annual leaching amounts of five macronutrients by rainwater was 173.33 kg hm -2 at FFC site, and 107.53 kg hm -2 at XQF site, in descending order of K>Ca>Mg. Negative values for nitrogen at both sites and for phosphorus at FFC site suggested that these two elements of nutrients were absorbed directly by tree crowns during precipitation period. Fig 5, Tab 4, Ref 15更多还原