High nitrate variability on an Alaskan permafrost hillslope dominated by alder shrubs
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Published:2022-05-19
Issue:5
Volume:16
Page:1889-1901
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
McCaully Rachael E., Arendt Carli A.ORCID, Newman Brent D., Salmon Verity G.ORCID, Heikoop Jeffrey M., Wilson Cathy J.ORCID, Sevanto Sanna, Wales Nathan A.ORCID, Perkins George B., Marina Oana C., Wullschleger Stan D.
Abstract
Abstract. In Arctic ecosystems, increasing temperatures are driving
the expansion of nitrogen (N) fixing shrubs across tundra landscapes. The
implications of this expansion to the biogeochemistry of Arctic ecosystems
are of critical importance and more work is needed to better understand the
form, availability, and transportation potential of N from these shrubs
across a variety of Arctic landscapes. To gain insights into the processes
controlling N within a permafrost hillslope system, the spatiotemporal
variability of nitrate (NO3-) and its environmental controls were
investigated at an alder (Alnus viridis spp. fruticosa) dominated permafrost tundra landscape in the
Seward Peninsula, Alaska, USA. Soil pore water was collected from locations
within alder shrubland growing along a well-drained hillslope and was compared to soil
pore water collected from locations outside (upslope, downslope, and between) the alder shrubland. Soil pore water
collected within alder shrubland had an average NO3-N (nitrogen from
nitrate) concentration of 4.27±8.02 mg L−1 and differed
significantly from locations outside alder shrubland (0.23±0.83 mg L−1; p<0.05). Temporal variation in NO3-N within and
downslope of alder shrubland co-occurred with precipitation events where
NO3- that accumulated in the soil was likely flushed downslope
during rainfall. These findings have important implications for nutrient
availability and mobility in N-limited permafrost systems that are
experiencing shrub expansion in response to a warming Arctic.
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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