Soil surface organic layers in Arctic Alaska: spatial distribution, rates of formation, and microclimatic effects

Journal of Geophysical Research: Biogeosciences
By: , and 

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Abstract

Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500–700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Soil surface organic layers in Arctic Alaska: spatial distribution, rates of formation, and microclimatic effects
Series title Journal of Geophysical Research: Biogeosciences
DOI 10.1002/2015JG002983
Volume 120
Issue 6
Year Published 2015
Language English
Publisher American Geophysical Union
Contributing office(s) Alaska Science Center Geography
Description 15 p.
First page 1150
Last page 1164
Country United States
State Alaska
Online Only (Y/N) N
Additional Online Files (Y/N) N