The 15N natural abundance (δ15N) of ecosystem samples reflects measures of water availability
The 15N natural abundance (δ15N) of ecosystem samples reflects measures of water availability
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DOI：
10.1071/pp98146
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发表时间：
1999-01-01
期刊：
影响因子：
--
通讯作者：
Stewart, GR
中科院分区：
文献类型：
--
作者：
Handley, LL;Austin, AT;Stewart, GR
我们收集了一个全球数据集，包括站点平均叶面δ (15)N、整个表层矿质土的δ (15)N以及相应的站点因子（年平均降雨量和温度、纬度、海拔和土壤pH）。全土壤δ (15)N与除海拔外的所有立地变量（包括叶面δ (15)N）均相关，在纬度和降雨量的回归下，全土壤δ (15)N为这些数据提供了最好的模型，占全土壤δ (15)N变化的49%。作为单线性回归，立地平均叶面δ (15)N与降雨量的相关性强于全土壤δ (15)N。一个较小的数据集显示，在单个生长季节，整个土壤δ (15)N、站点平均叶片δ (15)N与土壤水分变化之间存在类似的负相关。水分有效性（通过降雨量和温度测量）与土壤或植物δ(15)氮之间的负相关关系在景观尺度上失效，在景观尺度上，湿点相对于其干燥的环境富含δ(15)氮。在这里，我们提供了全球和季节数据，假设了水有效性和生态系统三角洲氮之间总体关系的近似机制，以及在许多湿/冷生态系统的树叶和土壤中发现的高度三角洲氮耗尽值的机制。这些假设得到了现有知识空白文献的补充，提出了将为陆地氮循环提供新见解的研究方向。我们的结论与Austin和Vitousek（1998）的结论一致，即叶片（和土壤）δ (15)N似乎与整个生态系统N的停留时间有关。
We assembled a globally-derived data set for site-averaged foliar delta(15)N, the delta(15)N of whole surface mineral soil and corresponding site factors (mean annual rainfall and temperature, latitude, altitude and soil pH). The delta(15)N of whole soil was related to all of the site variables (including foliar delta(15)N) except altitude and, when regressed on latitude and rainfall, provided the best model of these data, accounting for 49% of the variation in whole soil delta(15)N. As single linear regressions, site-averaged foliar delta(15)N was more strongly related to rainfall than was whole soil delta(15)N. A smaller data set showed similar, negative correlations between whole soil delta(15)N, site-averaged foliar delta(15)N and soil moisture variations during a single growing season. The negative correlation between water availability (measured here by rainfall and temperature) and soil or plant delta(15)N fails at the landscape scale, where wet spots are delta(15)N-enriched relative to their drier surroundings. Here we present global and seasonal data, postulate a proximate mechanism for the overall relationship between water availability and ecosystem delta(15)N and, newly, a mechanism accounting for the highly delta(15)N-depleted values found in the foliage and soils of many wet/cold ecosystems. These hypotheses are complemented by documentation of the present gaps in knowledge, suggesting lines of research which will provide new insights into terrestrial N-cycling. Our conclusions are consistent with those of Austin and Vitousek (1998) that foliar (and soil) delta(15)N appear to be related to the residence time of whole ecosystem N.