Document Type

Article

Publication Date

11-2024

Department

College of Forest Resources and Environmental Science

Abstract

In the Northern Hemisphere, anthropogenic nitrogen (N) deposition contributed to the enhancement of the global terrestrial carbon (C) sink, partially offsetting CO2 emissions. Across several long-term field experiments, this ecosystem-level response was determined to be driven, in part, by the suppression of microbial activity associated with the breakdown of soil organic matter. However, since the implementation of emission abatement policies in the 1970s, atmospheric N deposition has declined globally, and the consequences of this decline are unknown. Here, we assessed the response of soil C storage and associated microbial activities, in a long-term field study that experimentally increased N deposition for 24 years. We measured soil C and N, microbial activity, and compared effect sizes of soil C in response to, and in recovery from, the N deposition treatment across the history of our experiment (1994–2022). Our results demonstrate that the accumulated C in the organic horizon has been lost and exhibits additional deficits 5 years post-termination of the N deposition treatment. These findings, in part, arise from mechanistic changes in microbial activity. Soil C in the mineral soil was less responsive thus far in recovery. If these organic horizon C dynamics are similar in other temperate forests, the Northern Hemisphere C sink will be reduced and climate warming will be enhanced.

Publisher's Statement

© 2024 The Author(s). Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America. Publisher’s version of record: https://doi.org/10.1002/ecy.4444

Publication Title

Ecology

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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