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Spatial and temporal dynamics of subarctic birch forest carbon exchange

Heliasz, Michal LU (2012)
Abstract (Swedish)
Popular Abstract in English

The long-term stability of the global terrestrial carbon sink has been a matter of concern in that a weakening would have serious consequences for atmospheric CO2 concentrations and, hence, for further changes in climate. High northern latitudes are of special importance for the global carbon budget as they store large amounts of organic matter in the soil and are expected to be the most strongly affected by climate change.

Here we investigate carbon exchange in the subarctic mountain birch forest growing on the limit where tree growth is possible. The study sites are located close to the Abisko village in northern Sweden, in the catchment of Lake Torneträsk. The investigated area is... (More)
Popular Abstract in English

The long-term stability of the global terrestrial carbon sink has been a matter of concern in that a weakening would have serious consequences for atmospheric CO2 concentrations and, hence, for further changes in climate. High northern latitudes are of special importance for the global carbon budget as they store large amounts of organic matter in the soil and are expected to be the most strongly affected by climate change.

Here we investigate carbon exchange in the subarctic mountain birch forest growing on the limit where tree growth is possible. The study sites are located close to the Abisko village in northern Sweden, in the catchment of Lake Torneträsk. The investigated area is under influence of increasing temperature and periodical insect outbreaks causing defoliation of the trees.

The last insect outbreak which has happened in 2004 caused at least 90 g C m-2 loss of carbon to the atmosphere and it turned the site from being carbon neutral in undisturbed years into a source of carbon. The forest was regenerating for 1-3 years after disturbances depending on the level of defoliation during outbreak.

The annual carbon uptake in the undisturbed forest was mainly dependent on the length of the growing season and the amount of incoming light used for photosynthesis. Climate change causes an increase in the length of the growing season and expansion of the forest on tundra-heath ecosystem.

The total annual loss of carbon by the forest to the atmosphere is mainly dependent on the thickness of the organic soil layer and temperature. Thickness of the organic soil in the forest is most likely connected with past transformation from a tundra-heath to the forest ecosystem. Loss of carbon in the tundra-heath ecosystem is limited by difficult to decompose carbon (carbon limitation) and expansion of birch with litter rich in easy to decompose carbon cause the newly established forest to be carbon source to the atmosphere. This study suggests that the invasion of deciduous tree species onto the carbon limited arctic tundra may cause high losses of soil carbon to the atmosphere. (Less)
Abstract
High northern latitudes are of special importance for the global carbon budget as they store large amounts of organic matter in the soil and are expected to be the most strongly affected by climate change.

Here we investigate carbon exchange in the subarctic mountain birch forest growing on the limit where tree growth is possible. The study sites are located close to the Abisko village in northern Sweden, in the catchment of Lake Torneträsk. The investigated area is under influence of increasing temperature and periodical insect outbreaks causing defoliation of the trees.

The last insect outbreak which has happened in 2004 caused at least 90 g C m-2 loss of carbon to the atmosphere and it turned the site from being C... (More)
High northern latitudes are of special importance for the global carbon budget as they store large amounts of organic matter in the soil and are expected to be the most strongly affected by climate change.

Here we investigate carbon exchange in the subarctic mountain birch forest growing on the limit where tree growth is possible. The study sites are located close to the Abisko village in northern Sweden, in the catchment of Lake Torneträsk. The investigated area is under influence of increasing temperature and periodical insect outbreaks causing defoliation of the trees.

The last insect outbreak which has happened in 2004 caused at least 90 g C m-2 loss of carbon to the atmosphere and it turned the site from being C neutral in undisturbed years into a source of carbon. The forest was regenerating for 1-3 years after disturbances depending on the level of defoliation during outbreak.

The annual cumulative gross primary production in the undisturbed forest was mainly dependent on the length of the growing season and the incoming radiation. Climate change causes an increase in the length of the growing season and expansion of the forest on tundra-heath ecosystem.

The annual cumulative respiration is mainly dependent on the thickness of the organic soil layer and temperature. Thickness of the organic soil in the forest is most likely connected with past transformation from a tundra-heath to the forest ecosystem. Respiration in the tundra-heath ecosystem is carbon limited and expansion of birch with litter rich in highly labile carbon cause the newly established forest to be carbon source to the atmosphere. This study suggests that the invasion of deciduous tree species onto the C limited arctic tundra may cause high losses of soil carbon to the atmosphere. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Vesala, Timo, Department of Physics, University of Helsinki, Finland
organization
publishing date
type
Thesis
publication status
published
subject
keywords
mountain birch, eddy covariance, carbon budget, insect outbreak, forest expansion, temporal variability, spatial variability
pages
132 pages
publisher
Department of Physical Geography and Ecosystem Science, Lund University
defense location
salen Världen, Geocentrum I, Sölvegatan 10, Lund
defense date
2012-06-11 10:00
ISBN
978-91-85793-27-3
language
English
LU publication?
yes
id
13dc4809-631b-4741-bf09-8d3f05f00cc4 (old id 2540445)
date added to LUP
2012-05-15 07:42:25
date last changed
2016-09-19 08:45:14
@misc{13dc4809-631b-4741-bf09-8d3f05f00cc4,
  abstract     = {High northern latitudes are of special importance for the global carbon budget as they store large amounts of organic matter in the soil and are expected to be the most strongly affected by climate change. <br/><br>
Here we investigate carbon exchange in the subarctic mountain birch forest growing on the limit where tree growth is possible. The study sites are located close to the Abisko village in northern Sweden, in the catchment of Lake Torneträsk. The investigated area is under influence of increasing temperature and periodical insect outbreaks causing defoliation of the trees.<br/><br>
The last insect outbreak which has happened in 2004 caused at least 90 g C m-2 loss of carbon to the atmosphere and it turned the site from being C neutral in undisturbed years into a source of carbon. The forest was regenerating for 1-3 years after disturbances depending on the level of defoliation during outbreak. <br/><br>
The annual cumulative gross primary production in the undisturbed forest was mainly dependent on the length of the growing season and the incoming radiation. Climate change causes an increase in the length of the growing season and expansion of the forest on tundra-heath ecosystem.<br/><br>
The annual cumulative respiration is mainly dependent on the thickness of the organic soil layer and temperature. Thickness of the organic soil in the forest is most likely connected with past transformation from a tundra-heath to the forest ecosystem. Respiration in the tundra-heath ecosystem is carbon limited and expansion of birch with litter rich in highly labile carbon cause the newly established forest to be carbon source to the atmosphere. This study suggests that the invasion of deciduous tree species onto the C limited arctic tundra may cause high losses of soil carbon to the atmosphere.},
  author       = {Heliasz, Michal},
  isbn         = {978-91-85793-27-3},
  keyword      = {mountain birch,eddy covariance,carbon budget,insect outbreak,forest expansion,temporal variability,spatial variability},
  language     = {eng},
  pages        = {132},
  publisher    = {ARRAY(0x943eba8)},
  title        = {Spatial and temporal dynamics of subarctic birch forest carbon exchange},
  year         = {2012},
}