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在福建南平地区 ,对两片杉木人工林 (标记为FFC和XQF)的氮素沉降进行了为期 3a(1994～ 1996 )的定位研究 .结果表明 ,降水通过林冠后 ,穿透雨的氮素含量没有发生明显变化 ,但树干径流的养分富集现象则十分显著 .降雨、穿透雨和树干径流中的氮素含量表现出明显的季节变化 ,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FFC和XQF监测场 ,每年从降雨中输入的NH+4 N分别为 8.73kghm-2 和 4.6 2kghm-2 ,NO-3 N分别为 9.36kghm-2 和 6 .83kghm-2 ,总计氮素输入分别为 18.0 9kghm-2 及 11.45kghm-2 ,其中16 .4% (2 .97kghm-2 )和 4.9% (0 .5 6kghm-2 )在降水过程中直接被两林分的林冠所吸收 .吸收行为主要出现在春、夏两季 ,这是杉木生长旺盛的阶段 ,而在秋、冬季则主要表现为淋溶 .林龄和密度是影响林冠对氮素吸收量的两个主要因子 .图 3表 1参 2 2
In the Nanping area of Fujian Province, the nitrogen deposition of two Chinese fir plantations (labeled as FFC and XQF) was studied for period 3a (1994 ~ 1996). The results showed that the nitrogen content of rain through the canopy But there was no obvious change in the runoff, but the nutrient enrichment of the trunk runoff was very significant.The rainfall, penetration rain and trunk runoff nitrogen content showed obvious seasonal changes, the lowest in summer, the highest in winter and the middle in spring and autumn The pattern is strongly controlled by rainfall. In the FFC and XQF monitoring fields, annual NH + 4 N input from rainfall is 8.73 kghm -2 and 4.6 2 kghm -2, respectively, and NO 3 N is 9.36 kghm -2 and 6 respectively. 83kghm-2, the total nitrogen input was 18.0 9kghm-2 and 11.45kghm-2 respectively, of which 16.4% (2.97kghm-2) and 4.9% (0.56kghm-2) Forest canopy absorption.The absorption behavior mainly occurs in spring and summer, which is the stage of vigorous growth of Chinese fir, but mainly in leaching in autumn and winter.The age and density of canopy affect the absorption of nitrogen Of the two main factors. Figure 3 Table 1 reference 2 2