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A green future with thawing permafrost mires? : a study of climate-vegetatiojn interactions in European subarctic peatlands

Bosiö, Julia LU (2013)
Abstract (Swedish)
Popular Abstract in Swedish

Projektioner om framtida klimat i Arktis och subarktis tyder på att drastiska förändrinar väntar regionen under det närmaste århundradet. Inte bara temperaturen spås öka utan även nederbörd, och då framför allt nederbörden under vinterhalvåret. Dessa förändringar kommer sannolikt att ha stor inverkan på miljön i Arktis och subarktis, och stora forksningsansträngningar har redan lagts på att undersöka hur

klimat och ekosystem påverkar varandra. Trots detta finns fortfarande luckor i vår kunskap om hur miljön kan tänkas reagera på framtidens klimatförändringar. I denna licenciatavhandling presenteras min forskning kring kopplingarna mellan klimat och vegetation i permafrostmyrar (även så... (More)
Popular Abstract in Swedish

Projektioner om framtida klimat i Arktis och subarktis tyder på att drastiska förändrinar väntar regionen under det närmaste århundradet. Inte bara temperaturen spås öka utan även nederbörd, och då framför allt nederbörden under vinterhalvåret. Dessa förändringar kommer sannolikt att ha stor inverkan på miljön i Arktis och subarktis, och stora forksningsansträngningar har redan lagts på att undersöka hur

klimat och ekosystem påverkar varandra. Trots detta finns fortfarande luckor i vår kunskap om hur miljön kan tänkas reagera på framtidens klimatförändringar. I denna licenciatavhandling presenteras min forskning kring kopplingarna mellan klimat och vegetation i permafrostmyrar (även så kallade palsmyrar) in den subarktiska delen av Fennoskandia. Permafrost kallas mark som förblir frusen året om

under två eller flera på varandra följande år. I Fennoskandia utgör dessa palsmyrar den yttre gränsen för förekomsten av permafrost i låglandsterräng. En kombination av klimat och miljö gör att marken här aldrig tillåts tina, men förekomsten av permafrost är därmed också mycket känslig för förändingar i klimat och/eller miljön. Genom att kombinera fältstudier av vegetationsmönster i ett antal palsmyrar i

regionen med spatial klimatdata för norra Fennoskandia kunde en projektion av framtida utbredning och förekomst av palsmyrar och dess vegetationsmönster modelleras. Därtill gjordes en experimentell studie i hur ökad snömängd påverkar fotosyntesen i vegetationen på en palsmyr i norra Sverige. Under sju vintrar ökades snömängden med hjälp av snöstaket, varpå effekten på vegetation och fotosyntes undersöktes under två somrar. Resultaten indikerar att palsmyrar in norra Fennoskandia har små möjligheter att fortsätta existera i ett framtida klimat, där majoriteten av regionens palsmyrar riskerar

att tina inom de närmaste 50-60 åren. Även växtligheten beräknas förändras, från torr hedvegetation till fuktig gräsvegetation när dessa palsmyrar tinar och klimat förändras. Experimentella studier av snöns inverkan på vegetation tyder även på att en relativt liten ökning i snömängd kan bidra till en markant förändring i artsammansättning och fotosyntes, till följd av ökad markfuktihet, marktemperatur och näringstillgång. Denna föränding kan bidra till både ökat kolupptag genom ökad fotosyntes, och ökade metanutsläpp då markfuktigehen ökar. (Less)
Abstract
Climate projections indicate that Arctic and sub-Arctic regions are facing a significant change in climate during the 21st century. With warmer temperatures precipitation is also expected to increase, and in particular winter precipitation. These changes are likely to have large impacts on the Arctic and subarctic environment, and extensive

research has focused on ecosystem-climate interactions in Arctic and sub-Arctic environments, but still the environmental response to such changes is not fully understood. This thesis presents the work and outcomes of my research on climate-vegetation interactions in permafrost (ground that remains frozen for two or more consecutive

years) mires in subarctic Fennoscandia. In this... (More)
Climate projections indicate that Arctic and sub-Arctic regions are facing a significant change in climate during the 21st century. With warmer temperatures precipitation is also expected to increase, and in particular winter precipitation. These changes are likely to have large impacts on the Arctic and subarctic environment, and extensive

research has focused on ecosystem-climate interactions in Arctic and sub-Arctic environments, but still the environmental response to such changes is not fully understood. This thesis presents the work and outcomes of my research on climate-vegetation interactions in permafrost (ground that remains frozen for two or more consecutive

years) mires in subarctic Fennoscandia. In this region permafrost mires demarks the outer border of lowland permafrost existence, where a combination of climatological and environmental conditions allows for the ground to remain frozen year round, making the permafrost particularly sensitive to changes. By combining field observations of vegetation patterns in permafrost mires throughout the study region with spatial data of the present (2008) and projected future climate in subarctic Fennoscandia the future vegetational patterns of these

permafrost mires were modeled. Further, the impact of increased snow cover on plant photosynthesis in these environments was assessed through field experiments on a subarctic permafrost mire, where the snow cover was manipulated during seven winters using snow fences.

The results suggest that a rapid transition from dry heath tundra vegetation to moist tussock tundra vegetation is to be expected in these permafrost mires with the warmer climate and increased precipitation projected for the studied region. The snow manipulation experiments suggest that even a moderate increase in snow cover

thickness increases plant photosynthesis on the long term. This increase in photosynthesis is attributed to the observed shift in plant species composition where moist tussock vegetation is likely to be favored by increased soil moisture, soil temperature and nutrient availability. However, the increased carbon uptake through higher photosynthesis rates is may be completely offset by increased methane

emissions from increased wetness in the thawing peatlands. (Less)
Please use this url to cite or link to this publication:
author
supervisor
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Fennoscandia, carbon, greenhouse gas, photosynthesis, PAR, snow, climate change, permafrost, peatland, subarctic
pages
88 pages
ISBN
978-91-85793-29-7
project
BECC
language
English
LU publication?
yes
id
a0b9696f-8d1a-44cd-8cf2-ce19dfd045b5 (old id 3448203)
date added to LUP
2013-05-31 12:17:16
date last changed
2016-09-19 08:45:17
@misc{a0b9696f-8d1a-44cd-8cf2-ce19dfd045b5,
  abstract     = {Climate projections indicate that Arctic and sub-Arctic regions are facing a significant change in climate during the 21st century. With warmer temperatures precipitation is also expected to increase, and in particular winter precipitation. These changes are likely to have large impacts on the Arctic and subarctic environment, and extensive<br/><br>
research has focused on ecosystem-climate interactions in Arctic and sub-Arctic environments, but still the environmental response to such changes is not fully understood. This thesis presents the work and outcomes of my research on climate-vegetation interactions in permafrost (ground that remains frozen for two or more consecutive<br/><br>
years) mires in subarctic Fennoscandia. In this region permafrost mires demarks the outer border of lowland permafrost existence, where a combination of climatological and environmental conditions allows for the ground to remain frozen year round, making the permafrost particularly sensitive to changes. By combining field observations of vegetation patterns in permafrost mires throughout the study region with spatial data of the present (2008) and projected future climate in subarctic Fennoscandia the future vegetational patterns of these<br/><br>
permafrost mires were modeled. Further, the impact of increased snow cover on plant photosynthesis in these environments was assessed through field experiments on a subarctic permafrost mire, where the snow cover was manipulated during seven winters using snow fences.<br/><br>
The results suggest that a rapid transition from dry heath tundra vegetation to moist tussock tundra vegetation is to be expected in these permafrost mires with the warmer climate and increased precipitation projected for the studied region. The snow manipulation experiments suggest that even a moderate increase in snow cover<br/><br>
thickness increases plant photosynthesis on the long term. This increase in photosynthesis is attributed to the observed shift in plant species composition where moist tussock vegetation is likely to be favored by increased soil moisture, soil temperature and nutrient availability. However, the increased carbon uptake through higher photosynthesis rates is may be completely offset by increased methane<br/><br>
emissions from increased wetness in the thawing peatlands.},
  author       = {Bosiö, Julia},
  isbn         = {978-91-85793-29-7},
  keyword      = {Fennoscandia,carbon,greenhouse gas,photosynthesis,PAR,snow,climate change,permafrost,peatland,subarctic},
  language     = {eng},
  pages        = {88},
  title        = {A green future with thawing permafrost mires? : a study of climate-vegetatiojn interactions in European subarctic peatlands},
  year         = {2013},
}