Enhanced foliar 15 N enrichment with increasing nitrogen addition rates: Role of plant species and nitrogen compounds

作者：Yinliu Wang, Guoxiang Niu, Ruzhen Wang, Kathrin Rousk, Ang Li, Muqier Hasi, Changhui Wang, J.J. Xue, Guojiao Yang, Xiao‐Tao Lü, Yong Jiang, Xingguo Han, Jianhui Huang · 发表于：Global Change Biology · 年份：2022 · DOI：10.1111/gcb.16555 · 被引用次数：34 · 研究领域：Soil Carbon and Nitrogen Dynamics、Silicon Effects in Agriculture、Plant nutrient uptake and metabolism

Abstract Determining the abundance of N isotope (δ 15 N) in natural environments is a simple but powerful method for providing integrated information on the N cycling dynamics and status in an ecosystem under exogenous N inputs. However, whether the input of different N compounds could differently impact plant growth and their 15 N signatures remains unclear. Here, the response of 15 N signatures and growth of three dominant plants ( Leymus chinensis , Carex duriuscula , and Thermopsis lanceolata ) to the addition of three N compounds (NH 4 HCO 3 , urea, and NH 4 NO 3 ) at multiple N addition rates were assessed in a meadow steppe in Inner Mongolia. The three plants showed different initial foliar δ 15 N values because of differences in their N acquisition strategies. Particularly, T. lanceolata (N 2 ‐fixing species) showed significantly lower 15 N signatures than L. chinensis (associated with arbuscular mycorrhizal fungi [AMF]) and C. duriuscula (associated with AMF). Moreover, the foliar δ 15 N of all three species increased with increasing N addition rates, with a sharp increase above an N addition rate of ~10 g N m −2 year −1 . Foliar δ 15 N values were significantly higher when NH 4 HCO 3 and urea were added than when NH 4 NO 3 was added, suggesting that adding weakly acidifying N compounds could result in a more open N cycle. Overall, our results imply that assessing the N transformation processes in the context of increasing global N deposition necessitates the conside...