Tree species is the major factor explaining C:N ratios in European forest soils
Tree species is the major factor explaining C:N ratios in European forest soils
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DOI：
10.1016/j.foreco.2013.06.047
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发表时间：
2014-01-01
影响因子：
3.7
通讯作者：
Hansen, K.
中科院分区：
文献类型：
--
作者：
Cools, N.;Vesterdal, L.;Hansen, K.
C:N 比率被认为是响应高大气氮 (N) 沉降的硝酸盐浸出的指标。然而，C:N 比受到许多其他与场地相关的因素的影响。本研究旨在揭示 ICP 森林大规模监测网络 4000 多个地块中森林地面、矿质土壤和泥炭表土 C:N 比率的决定因素。第一个目标是量化整个欧洲森林的森林地面、矿物质和泥炭土的 C:N 比率。其次，我们使用增强回归树分析 (BRT) 确定了解释该 C:N 比率的主要因素，包括 15 个地点和环境变量。 95% 的 C:N 比率在森林地面中介于 16 到 44 之间，在泥炭表土中介于 13 到 44 之间，在矿物表土中介于 10 到 32 之间。在通气森林地表和矿质土壤中，碳氮比随着深度的增加而降低，而在水生森林地表和泥炭中，没有观察到随深度的明显趋势。树种显然是森林地表和表土中碳氮比最重要的解释变量，而在更深的矿质土壤层中，它是土壤类型。森林地面和表层矿质土壤的碳氮比最低的是刺槐 (Robinia pseudoacacia L.) 和黑桤木 (Alnus glutinosa L) 林，这两种树种都是固氮树种。在森林地表中，松树、栓皮栎 (Quercus suber L.) 和桉树等常绿树种的碳氮比最高，而松树和花旗松 (Pseudotsuga menziesii (Mirb.) Franco) 在矿质土壤中的碳氮比最高。森林地面和矿物表土的第二个最重要的解释变量是生物地理分区（生态区）。在泥炭表土和更深的矿质土壤层中，它是腐殖质类型。在欧洲范围内，沉积和气候变量并不重要。对八种主要森林树种的进一步分析表明，环境变量对碳氮比的影响取决于树种。对于具有典型地中海分布的阿勒颇松 (Pinus halepensis Miller) 和圣栎 (Quercus Hex L.)，氮和硫沉积与碳氮比之间似乎呈正相关。这项研究表明，在没有明确考虑树种的情况下，将碳氮比作为欧洲森林氮状况的一般指标过于简单化，可能会导致误导性的结论。 (C) 2013 Elsevier B.V. 保留所有权利。
The C:N ratio is considered as an indicator of nitrate leaching in response to high atmospheric nitrogen (N) deposition. However, the C:N ratio is influenced by a multitude of other site-related factors. This study aimed to unravel the factors determining C:N ratios of forest floor, mineral soil and peat top soils in more than 4000 plots of the ICP Forests large-scale monitoring network. The first objective was to quantify forest floor, mineral and peat soil C:N ratios across European forests. Secondly we determined the main factors explaining this C:N ratio using a boosted regression tree analysis (BRT), including fifteen site and environmental variables.Ninety-five percent of the C:N ratios were between 16 and 44 in the forest floor, between 13 and 44 in the peat topsoil and between 10 and 32 in the mineral topsoil. Within the aerated forest floor and the mineral soil, the C:N ratios decreased with depth, while in the hydromorphic forest floor and the peats no clear trend with depth was observed.Tree species was clearly the most important explanatory variable for the C:N ratio in both forest floors and topsoils, while it was soil type in the deeper mineral soil layers. The lowest C:N ratios both in the forest floor and the top mineral soil were found in black locust (Robinia pseudoacacia L.) and black alder (Alnus glutinosa L) stands, both N fixing tree species. While in the forest floor the highest C:N ratios were found in evergreen species like pine, cork oak (Quercus suber L.) and eucalyptus, the pine species and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) showed the highest C:N ratios in the mineral soil. The second most important explanatory variable in the forest floor and mineral topsoil was the biogeographical zoning (ecoregion). In the peat topsoil and in the deeper mineral soil layers it was the humus type. Deposition and climatic variables were of minor importance at the European scale.Further analysis for eight main forest tree species individually, showed that the influence of environmental variables on C:N ratios was tree species dependent. For Aleppo pine (Pinus halepensis Miller) and holm oak (Quercus Hex L.), both with a typical Mediterranean distribution, the relationship between N and S deposition and C:N ratio appeared to be positive. This study suggests that applying C:N ratios as a general indicator of the N status in forests at the European level, without explicitly accounting for tree species, is too simplistic and may result in misleading conclusions. (C) 2013 Elsevier B.V. All rights reserved.