Enhanced foliar 15N enrichment with increasing nitrogen addition rates: Role of plant species and nitrogen compounds. Issue 6 (20th December 2022)

• Record Type: Journal Article
• Authors: Wang, Yinliu; Niu, Guoxiang; Wang, Ruzhen; Rousk, Kathrin; Li, Ang; Hasi, Muqier; Wang, Changhui; Xue, Jianguo; Yang, Guojiao; Lü, Xiaotao; Jiang, Yong; Han, Xingguo; Huang, Jianhui
• Is Part Of: Global change biology. Volume 29:Issue 6(2023)
• Page Start: 1591
• Page End: 1605
• Publication Date: 2022-12-20
• Subjects: arbuscular mycorrhiza -- foliar N concentration -- inorganic N -- N compounds -- N deposition -- N fixation -- δ15N; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16555
• Languages: English
• ISSNs: 1354-1013

Abstract

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 (NH4 HCO3, urea, and NH4 NO3 ) 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 (N2 ‐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 NH4 HCO3 and urea were added than when NH4 NO3 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 consideration of N deposition rates, forms of the deposited N compounds, and N utilization strategies of the co‐existing plant species in the ecosystem. Abstract : We explored the response of foliar 15 N signatures of three dominant plants to the N addition of different compounds and rates based on a field work in a meadow steppe. The foliar δ 15 N of the three species increased with increasing N addition rates, but differences in δ 15 N among plant species did not converge after N addition mainly because of their ability to access different N forms. Moreover, foliar δ 15 N values were significantly higher with addition of NH4 HCO3 and urea than NH4 NO3, suggesting adding weakly acidifying N compounds could result in a more open N cycle.