Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Soil Biology and Biochemistry 42 (2010): 611-617, doi:10.1016/j.soilbio.2009.12.011.
Description:
Arctic climate change is expected to lead to a greater frequency of extreme winter
warming events. During these events, temperatures rapidly increase to well above 0ºC for
a number of days, which can lead to snow melt at the landscape scale, loss of insulating
snow cover and warming of soils. However, upon return of cold ambient temperatures,
soils can freeze deeper and may experience more freeze-thaw cycles due to the absence
of a buffering snow layer. Such loss of snow cover and changes in soil temperatures may
be critical for litter decomposition since a stable soil microclimate during winter
(facilitated by snow cover) allows activity of soil organisms. Indeed, a substantial part of
fresh litter decomposition may occur in winter. However, the impacts of extreme winter
warming events on soil processes such as decomposition have never before been
investigated. With this study we quantify the impacts of winter warming events on fresh
litter decomposition using field simulations and lab studies.
Winter warming events were simulated in sub-Arctic heathland using infrared
heating lamps and soil warming cables during March (typically the period of maximum
snow depth) in three consecutive years of 2007, 2008, and 2009. During the winters of
2008 and 2009, simulations were also run in January (typically a period of shallow snow
cover) on separate plots. The lab study included soil cores with and without fresh litter
subjected to winter warming simulations in climate chambers.
Litter decomposition of common plant species was unaffected by winter warming
events simulated either in the lab (litter of Betula pubescens ssp. czerepanovii), or field
(litter of Vaccinium vitis-idaea, and B. pubescens ssp. czerepanovii) with the exception of
Vaccinium myrtillus (a common deciduous dwarf shrub) that showed less mass loss in
response to winter warming events. Soil CO2 efflux measured in the lab study was (as
expected) highly responsive to winter warming events but surprisingly fresh litter
decomposition was not. Most fresh litter mass loss in the lab occurred during the first 3-4
weeks (simulating the period after litter fall).
In contrast to past understanding, this suggests that winter decomposition of fresh
litter is almost non-existent and observations of substantial mass loss across the cold
season seen here and in other studies may result from leaching in autumn, prior to the
onset of “true” winter. Further, our findings surprisingly suggest that extreme winter
warming events do not affect fresh litter decomposition.
Description:
This research was supported by a Leverhulme Trust (UK) grant to GKP and
TVC, by a grant from the Norwegian Research Council awarded to JWB, and by ATANS
grants (EU Transnational Access Programme) to JWB, GKP and SB.
Keywords:
Arctic
;
Betula pubescens ssp. czerepanovii
;
Climate change
;
Decomposition
;
Extreme weather
;
Freeze-thaw
;
Snow
;
Vaccinium vitis-idaea
;
V. myrtillus
;
Winter warming event
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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