Legumes that possess the capacity to fix atmospheric nitrogen (N) via symbiotic N₂ fixation are widely considered to have the potential to regulate ecosystem N cycling. However, the N dynamics of those N₂-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 (δ¹⁵N) 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 δ¹⁵N (ranging from − 0.67 to 0.60‰) and soil δ¹⁵N (ranging from 0.60 to 5.71‰), but no correlation was observed between them. Foliar δ¹⁵N 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 δ¹⁵N 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 δ¹⁵N were foliar N, foliar C/N, growing season precipitation, growing season temperature and soil pH, whereas those on soil δ¹⁵N 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 δ¹⁵N mainly via their effects on soil pH and foliar N, while affected soil δ¹⁵N 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 N₂ fixation, which has resulted in the decoupling of N dynamics between plant and soil, and in different patterns and controls of foliar and soil δ¹⁵N across climatic, edaphic and biotic gradients.

拥有通过共生N ₂固定来固定大气氮（N）的能力的豆类被广泛认为具有调节生态系统N循环的潜力。然而，对那些固定N _2的物种响应于气候，水生和生物因子变化的N动态的了解并不充分，特别是对于特别容易受到气候变化影响的高山植物。在这项工作中，叶面和土壤氮同位素组成（δ ¹⁵的N）鬼箭锦鸡儿，主要生长在高山地区豆科植物灌木，由跨越2666公里东西样35位点进行测量。结果表明，有叶面δ之间显著差异¹⁵ N（范围从- 0.67〜0.60‰）和土壤δ¹⁵ N（范围为0.60至5.71‰），但两者之间没有相关性。叶面δ ¹⁵ N含量上升与生长季节温度，叶面N浓度，并用高度，叶碳（C）浓度，叶面碳氮比（C / N），和土壤pH值下降，而土壤δ ¹⁵ n，其中高度增加，并且随土壤C，土壤N，土壤C / N和土壤电导率而降低。主成分分析表明，在叶δ的显著影响因素¹⁵ Ñ是叶面N，叶面C / N，生长期沉淀，生长期温度和土壤pH值，而那些对土壤δ ¹⁵N是土壤电导率，土壤C，土壤N，土壤C / N，叶面C，生长季节的降水量和生长季节的温度。结构方程模型表明，在生长季节的气温和降水影响叶面δ ¹⁵ Ñ主要通过它们对土壤的pH值的影响和叶面N，而受影响的土壤δ ¹⁵ Ñ主要由它们对土壤的电导率和土壤C / N的影响。本研究提供了有力的证据表明C. jubata在高山地区取得Ñ主要由共生Ñ ₂固定，这导致在N-动力学植物和土壤之间，并且在叶面和土壤的不同的图案和控制的解耦δ ¹⁵到N个气候，地球和生物梯度。