Impact of nitrogen deposition on nitrogen cycling in forests: a synthesis of NITREX data
Impact of nitrogen deposition on nitrogen cycling in forests: a synthesis of NITREX data
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DOI：
10.1016/s0378-1127(97)00124-2
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发表时间：
1998-02-01
影响因子：
3.7
通讯作者：
Tietema, A
中科院分区：
文献类型：
--
作者：
Gundersen, P;Emmett, BA;Tietema, A
通过比较NITREX试验点（瑞典Gardsjon（GD）、丹麦Klosterhede（KH）、英国威尔士Aber（AB）、荷兰Speuld（SP）和荷兰Ysselsteyn（YS））5个针叶林林分植被和土壤中氮通量、氮浓度和氮库大小，研究了氮沉降的影响。这些地点的氮沉降梯度为13至59 kg N ha（-1）yr（-1）。通过实验室和田间培养测量土壤氮转化率是现场比较的一部分。此外，分析中还包括低沉积点（GD、KH、AB）4-5年NH 4 NO3添加（35 kg N ha（-1）yr（-1））和高沉积点（SP、YS）6年N去除（屋顶）的结果。显着相关性被发现之间的一系列变量，包括在树叶和凋落物中的N浓度，土壤N转化率和森林地面特征。利用主成分分析（PCA）的方法，这些变量被总结为一个指数的网站N状态，分配最低的N状态GD和最高的YS。除AB天然富氮外，站点氮素状况随氮沉降而增加。硝态氮淋失量与氮素状况呈显著相关，与氮沉降量无显著相关性。森林地被物质量和根系生物量随着氮素水平的增加而减少，矿质土壤的特征与植被和森林地被物变量不相关。高C/N比的矿质土壤中的高氮沉积的网站（SP，YS）表明，矿质土壤池变化缓慢，不需要改变氮饱和发生。在实验室培养测得的氮转化率不同意，以及在现场测量的速率，除了在实验室和“净”矿化在该领域的“毛”矿化之间的良好相关性。氮浓度和通量的变化后，操作的N输入遵循预期的方向从现场比较：增加在N添加和N去除网站减少。硝态氮淋溶反应在第一年的治疗在所有网站，而在植被和土壤中的反应被推迟。操作处理的N状态的变化相比，网站之间的差异很小。硝态氮淋失的变化在低氮状态的网站和大量的高氮状态的网站。氮限制和氮饱和的森林生态系统可以定量表征。(C)1998年Elsevier Science B.V.
Impact of nitrogen (N) deposition was studied by comparing N fluxes, N concentrations and N pool sizes in vegetation and soil in five coniferous forest stands at the NITREX sites: Gardsjon (GD), Sweden, Klosterhede (KH), Denmark, Aber (AB), Wales, UK, Speuld (SP), the Netherlands, and Ysselsteyn (YS), the Netherlands. The sites span a N-deposition gradient from 13 to 59 kg N ha(-1) yr(-1). Measurements of soil N transformation rates by laboratory and field incubations were part of the site comparison. Further, results from 4-5 yr of NH4NO3, addition (35 kg N ha(-1) yr(-1)) at low deposition sites (GD, KH, AB) and 6 yr of N removal (roofs) at high deposition sites (SP, YS) were included in the analysis. Significant correlations were found between a range of variables including N concentrations in foliage and litter, soil N transformation rates and forest floor characteristics. Using the methods from principal component analysis (PCA) these variables were summarized to an index of site N status that assigned the lowest N status to GD and the highest to YS. Site N status increased with N deposition with the exception that AB was naturally rich in N. Nitrate leaching was significantly correlated with N status but not correlated with N deposition. Forest floor mass and root biomass decreased with increased N status, Characteristics of the mineral soil were not correlated with vegetation and forest floor variables. High C/N ratios in the mineral soil at the high-N deposition sites (SP, YS) suggest that the mineral soil pool changes slowly and need not change for N saturation to occur. Nitrogen transformation rates measured in laboratory incubations did not agree well with rates measured in the field except for a good correlation between 'gross' mineralization in the laboratory and 'net' mineralization in the field. The changes in N concentrations and fluxes after manipulation of N input followed the direction expected from the site comparison: increases at N addition and decreases at N removal sites. Nitrate leaching responded within the first year of treatment at all sites, whereas responses in vegetation and soil were delayed. Changes in N status by the manipulation treatments were small compared to the differences between sites. Changes in nitrate leaching were small at the low-N status sites and substantial at the high-N status sites. Nitrogen-limited and N-saturated forest ecosystems could be characterized quantitatively. (C) 1998 Elsevier Science B.V.