The effects of site preparation on carbon fluxes at two clear-cuts in southern Sweden
(2014) In Student thesis series INES NGEM01 20141Dept of Physical Geography and Ecosystem Science
- Abstract
- Clear-cutting is a common forest management practice. It alters the carbon balance of forests by eliminating photosynthesis through canopy removal and affecting autotrophic and heterotrophic respiration. In Sweden, almost 200 000 ha of forest is clear-cut every year and site preparation is carried out on more than 80% of it. The effects of different site preparation methods on the soil CO2 fluxes were studied at two adjacent clear-cuts in southern Sweden from June to October 2013.
The first site was a recently harvested clear-cut, where a block experiment was established to compare soil CO2 flux of harrowing and mounding site preparation with control plots using chamber measurements. Four treatments were compared: undisturbed soil... (More) - Clear-cutting is a common forest management practice. It alters the carbon balance of forests by eliminating photosynthesis through canopy removal and affecting autotrophic and heterotrophic respiration. In Sweden, almost 200 000 ha of forest is clear-cut every year and site preparation is carried out on more than 80% of it. The effects of different site preparation methods on the soil CO2 fluxes were studied at two adjacent clear-cuts in southern Sweden from June to October 2013.
The first site was a recently harvested clear-cut, where a block experiment was established to compare soil CO2 flux of harrowing and mounding site preparation with control plots using chamber measurements. Four treatments were compared: undisturbed soil (control), mineral pit after harrowing (harrowing-mineral), mound with double humus layer (harrowing-mound) and mound with double humus layer capped with mineral soil (mounding). The highest soil CO2 fluxes were obtained from harrowing-mound plots due to the double humus layer and increased temperatures. Although mounding plots had similar carbon content and high temperatures as harrowing-mound plots, the flux was suppressed by too low soil water content. Control plots showed higher soil respiration than mounding except in July, when the flux was inhibited by very dry conditions. The lowest soil CO2 flux was found from exposed mineral soil as humus layer had been removed.
The other site was a harrowed 2-year-old clear-cut. Chamber measurements and eddy-covariance measurements were carried out to study the carbon balance of the site. The harrowing-mound plots at the recently harvested site had higher soil respiration than at the 2-year-old site due to fresh substrate available for decomposition. However, the respiration from mineral plots at the 2-year-old site was higher than at the recently harvested site probably due to the enhanced root growth and increased belowground autotrophic respiration. The 2-year-old harrowed site was a source of carbon by 145 g C m-2 during the study period from the end of May to the end of August. Soil respiration contributed a major part to the ecosystem respiration at a 2-year-old site showing that site preparation had an important effect determining not just soil respiration but carbon balance of the site. The results highlight the importance of studying the carbon balance continuously during stand development to determine the long-term effects of site preparation. (Less) - Abstract
- Popular science
The carbon balance of the forest ecosystems is determined by the uptake and release of carbon. Forests take up carbon dioxide (CO2) by photosynthesis and release by respiration. One part of the assimilated carbon is respired back to the atmosphere by vegetation. The other part is respired by soil microbes which decompose organic material in soil. The microbial respiration is controlled by environmental factors like temperature, soil water content and substrate availability. When trees are cut, the carbon uptake is removed. However, the soil respiration increases as there is a lot of decomposable litter available for microbes. Therefore the site becomes a source of carbon. The soils of the clear-cuts are commonly prepared... (More) - Popular science
The carbon balance of the forest ecosystems is determined by the uptake and release of carbon. Forests take up carbon dioxide (CO2) by photosynthesis and release by respiration. One part of the assimilated carbon is respired back to the atmosphere by vegetation. The other part is respired by soil microbes which decompose organic material in soil. The microbial respiration is controlled by environmental factors like temperature, soil water content and substrate availability. When trees are cut, the carbon uptake is removed. However, the soil respiration increases as there is a lot of decomposable litter available for microbes. Therefore the site becomes a source of carbon. The soils of the clear-cuts are commonly prepared before planting new trees or seedlings. As forests have the potential to mitigate climate change by sequestering carbon, it is important to decrease the negative effect of clear-cutting. The effects of different site preparation methods on the soil respiration were studied at two adjacent clear-cuts in southern Sweden from June to October 2013.
The first site was a recently harvested forest, where soil respiration of harrowing and mounding site preparation was compared with undisturbed soil. Four soil treatments were compared: undisturbed soil (control), mineral pit after harrowing (harrowing-mineral), mound with double humus layer (harrowing-mound) and mound with double humus layer capped with mineral soil (mounding). The highest soil respiration was obtained from harrowing-mound plots due to the double humus layer and increased temperatures. Although mounding plots had similar organic matter content and high temperatures as harrowing-mound plots, the flux was suppressed by too low soil water content. Control plots showed higher soil respiration than mounding except in July, when the flux was inhibited by very dry conditions. The lowest soil respirtion was found from exposed mineral soil as humus layer had been removed.
The other site was a harrowed 2-year-old clear-cut. Soil respiration and carbon balance of the site were studied. The soil respiration from harrowing treatments was compared between two sites. The harrowing-mound plots at the recently harvested site had higher soil respiration than at the 2-year-old site due to fresh substrate available for decomposition. However, the soil respiration from mineral plots was higher at the 2-year-old site probably due to the enhanced root growth and increased root respiration. The 2-year-old harrowed site was a source of carbon during the study period from the end of May to the end of August. Soil respiration contributed a major part to the ecosystem respiration at a 2-year-old site showing that site preparation had an important effect determining not just soil respiration but carbon balance of the site. The results highlight the importance of studying the carbon balance continuously during stand development to determine the long-term effects of site preparation. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4467390
- author
- Nogu, Liisi LU
- supervisor
-
- Patrik Vestin LU
- Anders Lindroth LU
- organization
- alternative title
- The effects of site preparation on soil respiration
- course
- NGEM01 20141
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- eddy covariance, soil CO2 flux, site preparation, physical geography, geography, chamber measurements
- publication/series
- Student thesis series INES
- report number
- 316
- language
- English
- id
- 4467390
- date added to LUP
- 2014-06-17 08:57:47
- date last changed
- 2014-06-17 08:57:47
@misc{4467390,
abstract = {{Popular science
The carbon balance of the forest ecosystems is determined by the uptake and release of carbon. Forests take up carbon dioxide (CO2) by photosynthesis and release by respiration. One part of the assimilated carbon is respired back to the atmosphere by vegetation. The other part is respired by soil microbes which decompose organic material in soil. The microbial respiration is controlled by environmental factors like temperature, soil water content and substrate availability. When trees are cut, the carbon uptake is removed. However, the soil respiration increases as there is a lot of decomposable litter available for microbes. Therefore the site becomes a source of carbon. The soils of the clear-cuts are commonly prepared before planting new trees or seedlings. As forests have the potential to mitigate climate change by sequestering carbon, it is important to decrease the negative effect of clear-cutting. The effects of different site preparation methods on the soil respiration were studied at two adjacent clear-cuts in southern Sweden from June to October 2013.
The first site was a recently harvested forest, where soil respiration of harrowing and mounding site preparation was compared with undisturbed soil. Four soil treatments were compared: undisturbed soil (control), mineral pit after harrowing (harrowing-mineral), mound with double humus layer (harrowing-mound) and mound with double humus layer capped with mineral soil (mounding). The highest soil respiration was obtained from harrowing-mound plots due to the double humus layer and increased temperatures. Although mounding plots had similar organic matter content and high temperatures as harrowing-mound plots, the flux was suppressed by too low soil water content. Control plots showed higher soil respiration than mounding except in July, when the flux was inhibited by very dry conditions. The lowest soil respirtion was found from exposed mineral soil as humus layer had been removed.
The other site was a harrowed 2-year-old clear-cut. Soil respiration and carbon balance of the site were studied. The soil respiration from harrowing treatments was compared between two sites. The harrowing-mound plots at the recently harvested site had higher soil respiration than at the 2-year-old site due to fresh substrate available for decomposition. However, the soil respiration from mineral plots was higher at the 2-year-old site probably due to the enhanced root growth and increased root respiration. The 2-year-old harrowed site was a source of carbon during the study period from the end of May to the end of August. Soil respiration contributed a major part to the ecosystem respiration at a 2-year-old site showing that site preparation had an important effect determining not just soil respiration but carbon balance of the site. The results highlight the importance of studying the carbon balance continuously during stand development to determine the long-term effects of site preparation.}},
author = {{Nogu, Liisi}},
language = {{eng}},
note = {{Student Paper}},
series = {{Student thesis series INES}},
title = {{The effects of site preparation on carbon fluxes at two clear-cuts in southern Sweden}},
year = {{2014}},
}