Symbiotic nitrogen fixation contributes to divergent patterns of foliar and soil nitrogen isotopic composition in an alpine legume shrub species

文献类型： 外文期刊

第一作者： Xu, Tingting

作者： Xu, Tingting;Ai, Zhe;Ma, Fei;Jia, Yanlong;Li, Shanlong;Philp, Joshua;Ma, Fei

作者机构：

关键词： Caragana jubata; Foliar δ N-15; Legume; Precipitation; Soil δ N-15; Temperature

期刊名称：BIOGEOCHEMISTRY （ 影响因子：4.825； 五年影响因子：4.691 ）

ISSN： 0168-2563

年卷期： 2021 年 153 卷 1 期

页码：

收录情况： SCI

摘要： Legumes that possess the capacity to fix atmospheric nitrogen (N) via symbiotic N-2 fixation are widely considered to have the potential to regulate ecosystem N cycling. However, the N dynamics of those N-2-fixing species in response to changes of climatic, edaphic and biotic factors are not well-understood, especially for alpine plants that are particularly susceptible to climate change. In this work, foliar and soil N isotopic composition (delta N-15) of Caragana jubata, a legume shrub species mainly growing in alpine regions, was measured from 35 sites across a 2666 km east-west transect. Results showed that there were significant differences between foliar delta N-15 (ranging from - 0.67 to 0.60 parts per thousand) and soil delta N-15 (ranging from 0.60 to 5.71 parts per thousand), but no correlation was observed between them. Foliar delta N-15 increased with growing season temperature, foliar N concentration, and decreased with altitude, foliar carbon (C) concentration, foliar carbon to nitrogen ratio (C/N), and soil pH, whereas soil delta N-15 increased with altitude and decreased with soil C, soil N, soil C/N, and soil electrical conductivity. A principal component analysis indicated that the significant influential factors on foliar delta N-15 were foliar N, foliar C/N, growing season precipitation, growing season temperature and soil pH, whereas those on soil delta N-15 were soil electrical conductivity, soil C, soil N, soil C/N, foliar C, growing season precipitation and growing season temperature. Structural equation modeling indicated that the temperature and precipitation during the growing season affected foliar delta N-15 mainly via their effects on soil pH and foliar N, while affected soil delta N-15 mainly by their effects on soil electrical conductivity and soil C/N. This study provides strong evidence that C. jubata in the alpine regions obtains N mainly by symbiotic N-2 fixation, which has resulted in the decoupling of N dynamics between plant and soil, and in different patterns and controls of foliar and soil delta N-15 across climatic, edaphic and biotic gradients.

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