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Seasonal and inter-annual variability of soil respiration at Skyttorp, a Swedish boreal forest

Wang, Min LU (2012) In Student thesis series INES NGEM01 20121
Dept of Physical Geography and Ecosystem Science
Abstract (Swedish)
The ecosystem carbon balance is the net result of CO2 uptake by photosynthesis and CO2 emission through ecosystem respiration and soil respiration is a major part of ecosystem respiration. Soil CO2 fluxes were continuously measured from August 2005 to November 2008 with an automatic chamber system at a boreal forest site in central Sweden to investigate the annual and seasonal variations of soil respiration (Rs) and its dependence on soil temperature and soil moisture.

The soil temperature varied from -2°C to 21°C at 3 cm depth, and top 5-cm soil water content was in the range of 5 vol% to 40 vol%. There were no large variations of soil temperature among all the chambers on the annual time scale. The CO2 fluxes in all chambers but one... (More)
The ecosystem carbon balance is the net result of CO2 uptake by photosynthesis and CO2 emission through ecosystem respiration and soil respiration is a major part of ecosystem respiration. Soil CO2 fluxes were continuously measured from August 2005 to November 2008 with an automatic chamber system at a boreal forest site in central Sweden to investigate the annual and seasonal variations of soil respiration (Rs) and its dependence on soil temperature and soil moisture.

The soil temperature varied from -2°C to 21°C at 3 cm depth, and top 5-cm soil water content was in the range of 5 vol% to 40 vol%. There were no large variations of soil temperature among all the chambers on the annual time scale. The CO2 fluxes in all chambers but one varied from 0 to 12 μmol m-2 s-1 in summer and from 0 to 5 μmol m-2 s-1 during winter. The fluxes in one chamber had larger fluctuations with the range of -4 to 24 μmol m-2 s-1 in summer time because of the influences of ground vegetation in the chamber. The variation of CO2 fluxes tightly followed the variation of soil temperature on seasonal and inter-annual time scale. The temperature sensitivity Q10 calculated on the annual time scale varied from 3.07 to 3.45 among 5 chambers. A positive correlation existed between Q10 and soil water content when soil water content was in the range of 15% to 30%, and Q10 was decreasing with increasing temperature. The R10 (the soil respiration rate at 10°C) regression model provided good estimated Rs in both daytime and nighttime. The photosynthesis rate of ground vegetation in the chamber was around 5 μmol m-2 s-1 by comparing the estimated CO2 fluxes and measured CO2 fluxes in the daytime. A decline of Rs rate was found in one chamber when soil water content was higher than 33% during growing season of 2008. The seasonal and inter-annual variability of soil CO2 fluxes were mainly explained by 3-cm soil temperature variation at Skyttorp site. (Less)
Abstract (Swedish)
Popular science
Temporal variation of soil respiration at Skyttorp
Soil respiration (Rs) is a major component of carbon fluxes from terrestrial biosphere to the atmosphere with contributing 30-80% of annual total ecosystem respiration in forests. Rs, refers to the production of CO2 from soil by respiration of root and microorganisms, is normally demonstrated by soil CO2 flux in the unit of μmol m-2 s-1. The variability of soil CO2 flux is controlled by environmental factors, such as soil temperature, soil water content, and substrate availability. Soil CO2 fluxes were continuously measured from August 2005 to November 2008 with an automatic chamber system at a boreal forest site in central Sweden,Skyttorp. The chamber system contained... (More)
Popular science
Temporal variation of soil respiration at Skyttorp
Soil respiration (Rs) is a major component of carbon fluxes from terrestrial biosphere to the atmosphere with contributing 30-80% of annual total ecosystem respiration in forests. Rs, refers to the production of CO2 from soil by respiration of root and microorganisms, is normally demonstrated by soil CO2 flux in the unit of μmol m-2 s-1. The variability of soil CO2 flux is controlled by environmental factors, such as soil temperature, soil water content, and substrate availability. Soil CO2 fluxes were continuously measured from August 2005 to November 2008 with an automatic chamber system at a boreal forest site in central Sweden,Skyttorp. The chamber system contained of six transparent chambers placed on the ground to measure the concentrations of CO2 every 10 seconds in each chamber in sequence when the lid of that chamber was closed, and a linear regression was applied on the continuously increasing CO2 concentration with time to determine the CO2 flux in each chamber.

The variation of CO2 fluxes tightly followed the variation of soil temperature at 3-cm depth on seasonal and inter-annual time scale. The CO2 fluxes in all chambers but one varied from 0 to 12 μmol m-2 s-1 in summer and from 0 to 5 μmol m-2 s-1 during winter, which were in the expected range of soil respiration rate. The fluxes in one chamber had larger fluctuations with the range of -4 to 24 μmol m-2 s-1 in summer time because of the impacts of ground vegetation in the chamber. The ground vegetation uptakes CO2 through photosynthesis in the daytime and produces CO2 by respiration during both daytime and nighttime. A R10 (the soil respiration rate at 10°C) regression model was used to estimate soil CO2 flux via using measured soil temperature. The photosynthesis rate of ground vegetation in the chamber was around 5 μmol m-2 s-1 by comparing the estimated CO2 fluxes and measured CO2 fluxes in the daytime. A decline of Rs rate was found in one chamber when soil water content was higher than 33% during growing season of 2008. The seasonal and annual variability of soil CO2 fluxes were mainly explained by 3-cm soil temperature variation at Skyttorp site. (Less)
Please use this url to cite or link to this publication:
author
Wang, Min LU
supervisor
organization
alternative title
Temporal variation of soil respiration at Skyttorp
course
NGEM01 20121
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Skyttorp, chamber system, soil respiration, CO2 flux, geography, physical geography
publication/series
Student thesis series INES
report number
260
language
English
additional info
Master degree thesis, 30 credits in Atmospheric Sciences & Biogeochemical Cycles. Department of Physical Geography and Ecosystems Science, Lund University.
id
3052940
date added to LUP
2012-10-25 13:30:07
date last changed
2014-06-18 11:40:56
@misc{3052940,
  abstract     = {Popular science
Temporal variation of soil respiration at Skyttorp 
Soil respiration (Rs) is a major component of carbon fluxes from terrestrial biosphere to the atmosphere with contributing 30-80% of annual total ecosystem respiration in forests. Rs, refers to the production of CO2 from soil by respiration of root and microorganisms, is normally demonstrated by soil CO2 flux in the unit of μmol m-2 s-1. The variability of soil CO2 flux is controlled by environmental factors, such as soil temperature, soil water content, and substrate availability. Soil CO2 fluxes were continuously measured from August 2005 to November 2008 with an automatic chamber system at a boreal forest site in central Sweden,Skyttorp. The chamber system contained of six transparent chambers placed on the ground to measure the concentrations of CO2 every 10 seconds in each chamber in sequence when the lid of that chamber was closed, and a linear regression was applied on the continuously increasing CO2 concentration with time to determine the CO2 flux in each chamber.

The variation of CO2 fluxes tightly followed the variation of soil temperature at 3-cm depth on seasonal and inter-annual time scale. The CO2 fluxes in all chambers but one varied from 0 to 12 μmol m-2 s-1 in summer and from 0 to 5 μmol m-2 s-1 during winter, which were in the expected range of soil respiration rate. The fluxes in one chamber had larger fluctuations with the range of -4 to 24 μmol m-2 s-1 in summer time because of the impacts of ground vegetation in the chamber. The ground vegetation uptakes CO2 through photosynthesis in the daytime and produces CO2 by respiration during both daytime and nighttime. A R10 (the soil respiration rate at 10°C) regression model was used to estimate soil CO2 flux via using measured soil temperature. The photosynthesis rate of ground vegetation in the chamber was around 5 μmol m-2 s-1 by comparing the estimated CO2 fluxes and measured CO2 fluxes in the daytime. A decline of Rs rate was found in one chamber when soil water content was higher than 33% during growing season of 2008. The seasonal and annual variability of soil CO2 fluxes were mainly explained by 3-cm soil temperature variation at Skyttorp site.},
  author       = {Wang, Min},
  keyword      = {Skyttorp,chamber system,soil respiration,CO2 flux,geography,physical geography},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {Seasonal and inter-annual variability of soil respiration at Skyttorp, a Swedish boreal forest},
  year         = {2012},
}