Spatial Distribution of Bioavailable Inorganic Nitrogen From Thawing Permafrost
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Arctic permafrost contains large amounts of nitrogen (N), which may be bioavailable upon permafrost thaw. Here, we have compiled inorganic N data from published studies on the active layer and permafrost layers combined with new data to quantify the spatial variability of bioavailable inorganic N in permafrost-affected ecosystems across the Northern Hemisphere. Ammonium (NH4+) and nitrate (NO3−) are typically extracted from samples using different agents and strength. The results of an extraction experiment are here used to recalculate published concentrations on NH4+ and NO3− to a “water extractable fraction.” The results show that upper permafrost across all sites and samples contains significantly more NH4+ compared to the root zone and was significantly and positively correlated with an increasing water/ice content despite a surprisingly high variation within and between sites. Based on the average reported permafrost thaw rates (0.4–0.8 cm y−1) for wet and dry landscape types, the average release of inorganic N (NH4+ and NO3−) from wet tundra ecosystems was calculated to be 2.0 [1.13–2.61] kg N ha−1 decade−1 and 1.3 [0.78–1.81] kg N ha−1 decade−1 for dry ecosystems. This brings permafrost-derived inorganic N on the same order of magnitude as biological nitrogen fixation in relatively dry tundra ecosystems but only marginally compared to nitrogen fixation in wet ecosystems. These landscape-specific variations highlight the need for improving the understanding of N mobilization linked to permafrost thawing, but also that N transfer from well-drained slopes to lower parts of the landscape can be important for the potential plant growth (greening) downslope from surrounding landscape types with faster permafrost thawing.
Original language | English |
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Article number | e2022GB007589 |
Journal | Global Biogeochemical Cycles |
Volume | 37 |
Issue number | 2 |
Number of pages | 12 |
ISSN | 0886-6236 |
DOIs | |
Publication status | Published - 2023 |
Bibliographical note
CENPERMOA[2023]
Publisher Copyright:
© 2023. The Authors.
- ammonium, Arctic, bioavailable nitrogen, permafrost
Research areas
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