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Nonlinear responses of ecosystem carbon fluxes to nitrogen deposition in an old-growth boreal forest

Citation

Xing, Aijun et al. (2021), Nonlinear responses of ecosystem carbon fluxes to nitrogen deposition in an old-growth boreal forest, Dryad, Dataset, https://doi.org/10.5061/dryad.f4qrfj6x0

Abstract

Nitrogen (N) deposition is known to increase carbon (C) sequestration in N-limited boreal forests. However, the long-term effects of N deposition on ecosystem carbon fluxes have been rarely investigated in old-growth boreal forests. Here we show that decade-long experimental N additions significantly stimulated net primary production (NPP) but the effect decreased with increasing N loads. The effect on soil heterotrophic respiration (Rh) shifted from a stimulation at low-level N additions to an inhibition at higher levels of N additions. Consequently, low-level N additions resulted in a neutral effect on net ecosystem productivity (NEP), due to a comparable stimulating effect on NPP and Rh, while NEP was increased by high-level N additions. Moreover, we found nonlinear temporal responses of NPP, Rh and NEP to low-level N additions. Our findings imply that actual N deposition in boreal forests likely exerts a minor contribution to their soil C storage.

Methods

Detailed methods concerning how the dataset were collected can be found in the related article.

Funding

Programs of Basic Science Centres, Award: 31988102

National Key Research and Development Program of China, Award: 2017YFC0503901

Key Research Program of Frontier Science, Chinese Academy of Sciences, Award: QYZDY-SSW-SMC011

National Natural Science Foundation of China, Award: 41877328

Fok Ying Tong Education Foundation, Award: 161015

National Natural Science Foundation of China, Award: 41630750