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Subarctic peatlands in a changing climate : greenhouse gas response to experimentally increased snow cover

Njuabe , Herbert Mbufong (2011) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract
The rate of change of our climate has been amplified since the industrial
revolution and is expected to change even further by the end of this century.
Global temperature and precipitation are expected to increase considerably
over the next century. These increases are expected to be magnified in the
Arctic regions. In a high latitude peatland like Storflaket, near Abisko
(Northern Sweden), at the fringe of the 0°C isotherm, the environment is quite
sensitive to changes in climate. Precipitation here is mainly in the form of
snow. Increases in snow cover will most likely affect permafrost and active
layer thickness (the layer on top of permafrost that thaws and refreezes
annually), since snow insulates the ground from the low... (More)
The rate of change of our climate has been amplified since the industrial
revolution and is expected to change even further by the end of this century.
Global temperature and precipitation are expected to increase considerably
over the next century. These increases are expected to be magnified in the
Arctic regions. In a high latitude peatland like Storflaket, near Abisko
(Northern Sweden), at the fringe of the 0°C isotherm, the environment is quite
sensitive to changes in climate. Precipitation here is mainly in the form of
snow. Increases in snow cover will most likely affect permafrost and active
layer thickness (the layer on top of permafrost that thaws and refreezes
annually), since snow insulates the ground from the low winter temperatures,
resulting in relatively warm ground temperatures.
With the vast stocks of carbon stored as peat in frozen mires, the thawing of
this landscape will possibly make it available for decomposition and
subsequent emissions as Greenhouse gases. A snow manipulation experiment
that simulates future scenarios of increased winter precipitation initiated in
2005 was further investigated to understand the impacts of increased snow
cover on the active layer thickness and the implications of this on carbon
dioxide and methane emissions. A 1m high snow fence has been installed on
Storflaket perpendicular to the prevailing wind direction every winter since
2005. The snow fences result in about doubled the snow depth on treatment
plots compared to control plots.
Active layer thickness has increased significantly on treatment plots after the
doubling of snow cover, which has in turn increased the emission of CO2 from
treated plots through ecosystem respiration. Also, there has been more
carbon uptake on the treatment plots than on the control plots. Thus, the
cycling of carbon has simply been enhanced. Significant differences were
recorded between control and treatment plots in terms of the CO2 exchange,
soil moisture content and the reflected PAR. Surprisingly, CH4 emission was
almost inexistent for both sites. This means that Storflaket continues to be a
very lucrative carbon sink. This thesis presents these results in detail and
discusses the possible reasons for the findings. (Less)
Abstract (Swedish)
Klimatförändringar har amplifierats sedan den industriella revolutionen och
modeller pekar på att förändringen kommer forsätta att öka åtminstone till
slutet av detta århundrande. Globala temperaturer och nederbörd förväntas
öka avsevärt under detta århundrade. Dessa ökningar förväntas bli särskilt
markanta i de arktiska områdena. Torvmyrar belägna på höga latituder vid
0ºC isothermen, såsom Storflaket nära Abisko, är särskilt känsliga för
klimatförändringar. Nederbörden faller huvudsakligen som snö i de här
områdena. En ökad snömängd kommer troligtvis påverka permafrost och det
aktiva lagret (lagret ovan permafrosten som tinar och fryser årligen), eftersom
snö isolerar marken från låga lufttemperaturer och resulterar i relativt... (More)
Klimatförändringar har amplifierats sedan den industriella revolutionen och
modeller pekar på att förändringen kommer forsätta att öka åtminstone till
slutet av detta århundrande. Globala temperaturer och nederbörd förväntas
öka avsevärt under detta århundrade. Dessa ökningar förväntas bli särskilt
markanta i de arktiska områdena. Torvmyrar belägna på höga latituder vid
0ºC isothermen, såsom Storflaket nära Abisko, är särskilt känsliga för
klimatförändringar. Nederbörden faller huvudsakligen som snö i de här
områdena. En ökad snömängd kommer troligtvis påverka permafrost och det
aktiva lagret (lagret ovan permafrosten som tinar och fryser årligen), eftersom
snö isolerar marken från låga lufttemperaturer och resulterar i relativt varma
marktemperaturer.
När landskap som detta börjar tina kommer stora lager av kol som varit lagrat
i torven vara tillgängligt för nedbrytning vilket leder till utsläpp av
växthusgaser. Ett snömanipulations-experiment som simulerar framtida
klimatscenarier med ökad vinternederbörd som initierades 2005, undersöktes
ytterligare för att förstå påverkan av ett ökat snödjup på aktiva lagret och
dess implikation på koldioxid och metanutsläpp. Ett 1 m högt snöstaket har
installerats årligen på Storflaket sedan 2005, vinkelrätt mot den rådande
vindriktningen. Snöstaken har resultatet i dubbelt så mycket snö på
behandlade ytor jämfört med kontrollytorna.
Aktiva lagret har ökat signifikant på behandlade ytor när snömängden
fördubblats, vilket i sin tur har ökat utsläppen av koldioxid genom ökad
ekosystem-respiration. Mer kol har tagits upp av marken i behandlade ytor
jämfört med kontrollytorna. Således har kolets kretslopp ökat. Signifikanta
skillnader uppmättes mellan kontroll och behandlade ytor för koldioxutsläpp,
markfuktighet, och reflekterad PAR (Photosynthetically Active Radiation).
Förvånansvärt nog var metanutsläppen nästan obefintliga från både
behandlade och kontrollytorna. Detta betyder att Storflaket fortsätter att vara
en lukrativ kolsänka. Den här uppsatsen presenterar dessa resultat och
diskuterar tänkbara anledningar till de uppmätta resultaten. (Less)
Please use this url to cite or link to this publication:
author
Njuabe , Herbert Mbufong
supervisor
organization
year
type
H2 - Master's Degree (Two Years)
subject
keywords
greenhouse gases, subarctic peatlands, geography, physical geography, climate change
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
199
language
English
id
1971208
date added to LUP
2011-05-30 11:15:41
date last changed
2011-12-21 12:12:55
@misc{1971208,
  abstract     = {The rate of change of our climate has been amplified since the industrial
revolution and is expected to change even further by the end of this century.
Global temperature and precipitation are expected to increase considerably
over the next century. These increases are expected to be magnified in the
Arctic regions. In a high latitude peatland like Storflaket, near Abisko
(Northern Sweden), at the fringe of the 0°C isotherm, the environment is quite
sensitive to changes in climate. Precipitation here is mainly in the form of
snow. Increases in snow cover will most likely affect permafrost and active
layer thickness (the layer on top of permafrost that thaws and refreezes
annually), since snow insulates the ground from the low winter temperatures,
resulting in relatively warm ground temperatures.
With the vast stocks of carbon stored as peat in frozen mires, the thawing of
this landscape will possibly make it available for decomposition and
subsequent emissions as Greenhouse gases. A snow manipulation experiment
that simulates future scenarios of increased winter precipitation initiated in
2005 was further investigated to understand the impacts of increased snow
cover on the active layer thickness and the implications of this on carbon
dioxide and methane emissions. A 1m high snow fence has been installed on
Storflaket perpendicular to the prevailing wind direction every winter since
2005. The snow fences result in about doubled the snow depth on treatment
plots compared to control plots.
Active layer thickness has increased significantly on treatment plots after the
doubling of snow cover, which has in turn increased the emission of CO2 from
treated plots through ecosystem respiration. Also, there has been more
carbon uptake on the treatment plots than on the control plots. Thus, the
cycling of carbon has simply been enhanced. Significant differences were
recorded between control and treatment plots in terms of the CO2 exchange,
soil moisture content and the reflected PAR. Surprisingly, CH4 emission was
almost inexistent for both sites. This means that Storflaket continues to be a
very lucrative carbon sink. This thesis presents these results in detail and
discusses the possible reasons for the findings.},
  author       = {Njuabe , Herbert Mbufong},
  keyword      = {greenhouse gases,subarctic peatlands,geography,physical geography,climate change},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {Subarctic peatlands in a changing climate : greenhouse gas response to experimentally increased snow cover},
  year         = {2011},
}