Elevational shifts in foliar‐soil δ15N in the Hengduan Mountains and different potential mechanisms. (29th June 2022)

• Record Type: Journal Article
• Authors: Chen, Qiong; Chen, Ji; Andersen, Mathias Neumann; Cheng, Xiaoli
• Is Part Of: Global change biology. Volume 28:Number 18(2022)
• Page Start: 5480
• Page End: 5491
• Publication Date: 2022-06-29
• Subjects: altitude -- forestland -- microbial assimilation -- nitrogen cycle -- stable isotope; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16306
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: The natural abundance of stable nitrogen isotopes (δ 15 N) provides insights into the N dynamics of terrestrial ecosystems, the determination of which is considered an effective approach for gaining a better understanding ecosystem N cycling. However, there is currently little information available regarding the patterns and mechanisms underlying the variation in foliar‐soil δ 15 N among mountain ecosystems. In this study, we examined the determinants of foliar‐soil δ 15 N in association with N transportation rates along an elevational gradient in the Hengduan Mountains. Despite the relatively high levels of available N produced from high N fixation and mineralization, we detected the lowest levels of foliar δ 15 N at 3500 m a.s.l., reflecting the stronger vegetation N limitation at medium high elevations. The enhanced vegetation N limitation was driven by the combined effects of higher microbial immobilization and inherent plant dynamic (the shifts of δ 15 N in vegetation preference, including vegetation community) with changing climate along the elevational gradient. Unexpectedly, we established that soil δ 15 N was characterized by an undulating rise and uncoupled correlation with foliar δ 15 N with increasing elevation, thereby indicating that litter input might not be a prominent driver of soil δ 15 N. Conversely, soil nitrification and denitrification were found to make a more pronounced contribution to the pattern of soil δ 15 N along the elevational gradient. Collectively, our results serve to highlight the importance of microbial immobilization in soil N dynamics and provide novel insights that will contribute to enhancing our understanding of N cycling as indicated by foliar‐soil δ 15 N along elevational gradients. Abstract : The δ 15 N was used in our study to provide the N dynamics of terrestrial ecosystems. We found the lowest level of foliar δ 15 N, reflecting the stronger vegetation N limitation at medium high elevations, which was prominently driven by higher microbial immobilization. Besides, soil nitrification and denitrification were mainly controller by the pattern of soil δ 15 N along the elevational gradient.