Upslope release—Downslope receipt? Multi-year plant uptake of permafrost-released nitrogen along an arctic hillslope
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As arctic permafrost continues to thaw, previously inaccessible nitrogen (N) becomes available to N-limited arctic plants. Increased N availability could enhance plant growth and thereby potentially offset climate-induced carbon release. Arctic plants can take up newly available permafrost-N locally upon release. However, in a topographically diverse arctic landscape, permafrost-N may be transported along hillslopes, away from the point-of-release. The extent to which topographical N transport can impact arctic vegetation change depends on whether N is retained locally, captured by downslope recipient plant communities, or transported away. We used stable isotope labelling (15N) to simulate upslope release of ammonium (NH4+) and nitrate (NO3−) from thawing permafrost on an arctic hillslope, western Greenland. We tracked the plant species-specific uptake of simulated permafrost-released N from the upslope point-of-release to the bottom of the slope through 4 years. We found that arctic tundra plants successfully acquired locally released permafrost-N, even in sloping terrain, and that N was strongly retained in the plant–soil system through multiple years. At the same time, we also importantly demonstrate that permafrost-N can be transported and taken up by plants up to 30 m downslope from the point-of-release. Especially NO3− was more easily redistributed vertically within the soil column compared to NH4+ and therefore potentially more accessible to plants. Specifically, plant species with fast N uptake capacity and deep-soil foraging strategies may have competitive advantages for capitalising on deep-soil released and topographically transported permafrost-N (here exemplified by Equisetum arvense and Salix glauca). Nevertheless, even mosses gained access to permafrost-N via vertical and lateral redistribution on the slope. Ultimately, the intricate balance between strong local N retention, downslope transport and plant species-specific uptake strategies may contribute to shaping arctic vegetation change. Synthesis. Across spatially complex arctic ecosystems, arctic plants can take up permafrost-released N both at the local point-of-release and at a considerable distance downslope. The potential for arctic plants to take advantage of topographically transported permafrost-N could lead to long-term and landscape-scale changes in species composition, plant productivity, and ultimately carbon and climate feedbacks across the Arctic.
Original language | English |
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Journal | Journal of Ecology |
Volume | 110 |
Pages (from-to) | 1896–1912 |
Number of pages | 17 |
ISSN | 0022-0477 |
DOIs | |
Publication status | Published - 2022 |
Bibliographical note
CENPERMOA[2022]
Publisher Copyright:
© 2022 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.
- arctic hillslope, climate change, permafrost thaw, plant species-specific N uptake, plant–soil (belowground) interactions, stable isotope labelling N, topographical N transport, tundra
Research areas
ID: 311865336