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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
In the Nanping area of Fujian, the litter and forest precipitation chemistry of two Chinese fir plantations with different stands and densities were studied for the period of 3 years (1994 ~ 1996) .At the 16th year, the stand density (n = 2 370hm-2) The annual litterfall of 41a stands (labeled as XQF) with plant density n = 1180hm-2 were 6 2 10 .7 kghm-2 and 3 146 .2 kghm-2, respectively, with the deciduous leaves accounting for the total weight of 76% and 68% .The annual return of five main nutrient elements in litter was 173.92 kghm-2 and 84.2 0 kghm-2, respectively, and the order of the quantities was Ca> N> Mg> K> P, There were two peaks in the month and November .In the two monitoring plots, the nutrient enrichment phenomenon was obvious after precipitation passed through the canopy. The rainfall, penetration rain and trunk runoff showed significant seasonal changes in nutrient concentration, both in summer and winter Highest in spring and autumn, and the pattern was strongly controlled by rainfall.The annual leaching amount of the five elements caused by precipitation in the two forests was 173.33 kghm-2 and 10 7.5 3 kghm-2, respectively, with the order of K> Ca> Mg, while N (and P of FFC) showed a negative value indicating that it was directly absorbed by the canopy layer. Nutrient return ecosystems have a significant impact. FIG. 5 Refs. 15