Nitrogen addition reduces soil respiration but increases the relative contribution of heterotrophic component in an alpine meadow

作者：Jinsong Wang, Bing Song, Fangfang Ma, Dashuan Tian, Yong Li, Tao Yan, Quan Quan, Fangyue Zhang, Zhaolei Li, Bingxue Wang, Qiang Gao, Weinan Chen, Shuli Niu · 发表于：Functional Ecology · 年份：2019 · DOI：10.1111/1365-2435.13433 · 被引用次数：98 · 研究领域：Soil Carbon and Nitrogen Dynamics、Peatlands and Wetlands Ecology、Soil and Water Nutrient Dynamics

Abstract Disentangling the relative response sensitivity of soil autotrophic ( R a ) and heterotrophic respiration ( R h ) to nitrogen (N) enrichment is pivotal for evaluating soil carbon (C) storage and stability in the scenario of intensified N deposition. However, the mechanisms underlying differential sensitivities of R a and R h and relative contribution of R h to soil respiration ( R s ) with increasing N deposition remain elusive. A manipulative field experiment with multi‐level N addition rates was conducted over 3 years (2015–2017) in an alpine meadow to explore the relative impact of N enrichment on R a and R h and the response of R h / R s ratio to the gradient of N addition. Soil respiration components had different sensitivities to N enrichment, with R a decreasing more than R h , leading to a higher R h / R s ratio as a function of increasing N addition rates. R a and R h decreased nonlinearly as N addition rates increased, with a critical load of 8 g N m −2 year −1 above which N enrichment significantly inhibited them. R a and R h were controlled by different abiotic and biotic factors, and the regulation of controlling factors on soil respiration components varied over time. N‐induced reduction in the relative abundance of forb significantly affected R a , and this effect was mainly evident in the second and third years. Nitrogen enrichment significantly changed R h in the third year, and the decreased R h under high doses of N addition could be attributed to ...