TY - JOUR
T1 - Missing nitrogen source during ecosystem succession within retrogressive thaw slumps in Alaska
AU - Buckeridge, Kate M.
AU - McLaren, Jennie R.
AU - Mack, Michelle C.
AU - Schuur, Edward A.G.
AU - Schimel, Joshua
N1 - Funding Information:
The material presented here is based on work supported by the U.S. National Science Foundation under collaborative Grants ARC-0806394, ARC-0806399, ARC-0806329, ARC-0806254, ARC-0806465, ARC-0806451, ARC-0806341, ARC-0806271, DEB-1026843 and OPP-0909507. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. We thank Andres Baron Lopez, Dad Roux-Michollet, Sean Schaeffer, Alyssa Raley, Ken Marchus, and Sadie Iverson for laboratory and field support, and the staff of the Toolik Field Station and CH2M-Hill Polar Services for logistical support.
Publisher Copyright:
© 2023 The Author(s). Published by IOP Publishing Ltd.
PY - 2023/6/1
Y1 - 2023/6/1
N2 - Retrogressive thaw slumps (RTS)—thermal erosion of soil and vegetation after ground ice thaw—are increasing. Recovery of plant biomass after RTS is important for maintaining Arctic carbon (C) stocks and is regulated by nutrient availability for new plant growth. Many RTS are characterized by verdant shrub growth mid-succession, atypical of the surrounding nutrient-limited tundra. Here, we investigated the potential for internal and external sources of nitrogen (N) and phosphorus (P) to support mid-successional shrub growth at three Alaskan RTS chronosequences. We assessed patterns of soil and microbial CNP, soil NP cycling rates and stocks, N inputs via biological N2-fixation, and thaw leachate over time after disturbance. We found a clear transfer of P stocks from mineral to organic soils with increasing site age, yet insufficient N from any one source to support observed shrub growth. Instead, multiple mechanisms may have contributed to mid-successional shrub growth, including sustained N-cycling with reduced plant biomass, N leaching from undisturbed tundra, uninvestigated sources of N2-fixation, and most promising given the large resource, deep mineral soil N stocks. These potential mechanisms of N supply are critical for the regulation of the Arctic C cycle in response to an increasingly common climate-driven disturbance.
AB - Retrogressive thaw slumps (RTS)—thermal erosion of soil and vegetation after ground ice thaw—are increasing. Recovery of plant biomass after RTS is important for maintaining Arctic carbon (C) stocks and is regulated by nutrient availability for new plant growth. Many RTS are characterized by verdant shrub growth mid-succession, atypical of the surrounding nutrient-limited tundra. Here, we investigated the potential for internal and external sources of nitrogen (N) and phosphorus (P) to support mid-successional shrub growth at three Alaskan RTS chronosequences. We assessed patterns of soil and microbial CNP, soil NP cycling rates and stocks, N inputs via biological N2-fixation, and thaw leachate over time after disturbance. We found a clear transfer of P stocks from mineral to organic soils with increasing site age, yet insufficient N from any one source to support observed shrub growth. Instead, multiple mechanisms may have contributed to mid-successional shrub growth, including sustained N-cycling with reduced plant biomass, N leaching from undisturbed tundra, uninvestigated sources of N2-fixation, and most promising given the large resource, deep mineral soil N stocks. These potential mechanisms of N supply are critical for the regulation of the Arctic C cycle in response to an increasingly common climate-driven disturbance.
KW - ecosystem succession
KW - soil carbon
KW - soil nitrogen cycling
KW - soil phosphorus
KW - thermokarst
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U2 - 10.1088/1748-9326/acd0c2
DO - 10.1088/1748-9326/acd0c2
M3 - Article
AN - SCOPUS:85159590265
SN - 1748-9318
VL - 18
JO - Environmental Research Letters
JF - Environmental Research Letters
IS - 6
M1 - 065003
ER -