摘要
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
Nitrogen deposition in Chinese fir ( Cunninghamia lanceolata ) plantations was monitored for three years (1994～1996) at two monitoring sites established in Nanping, Fujian. The results showed that nitrogen concentration in throughfall was not altered significantly through forest canopies at the both sites, but that in stemflow was enriched remarkably. Nitrogen 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 inputs in rainfall at FFC and XQF sites were 8.73 kg hm -2 and 4.62 kg hm -2 for NH + 4 N, 9.36 kg hm -2 and 6.83 kg hm -2 for NO - 3 N, with total nitrogen inputs of 18.09 kg hm -2 and 11.45 kg hm -2 , respectively. Among them 16.4%(2.97 kg hm -2 )and 4.9%(0.56 kg hm -2 ) were absorbed directly by the tree crowns during precipitation period at the two sites, respectively. Uptake action for nitrogen occurred mainly in spring and summer when the trees were in their rapid growth period, whereas nitrogen was leached from tree crowns during autumn and winter months. Stand ages and densities are supposed to be two major factors affecting uptake quantities for nitrogen. Fig 3, Tab 1, Ref 22
出处
《应用与环境生物学报》
CAS
CSCD
2000年第2期133-137,共5页
Chinese Journal of Applied and Environmental Biology
基金
日本国际绿化推进中心资助项目
关键词
杉木人工林
生物地球化学循环
氮素沉降
生态
Chinese fir plantation
biogeochemical cycle
nitrogen deposition
seasonal dynamics
