Articles | Volume 13, issue 8
Biogeosciences, 13, 2367–2378, 2016
https://doi.org/10.5194/bg-13-2367-2016
Biogeosciences, 13, 2367–2378, 2016
https://doi.org/10.5194/bg-13-2367-2016

Research article 22 Apr 2016

Research article | 22 Apr 2016

Effects of management thinning on CO2 exchange by a plantation oak woodland in south-eastern England

Matthew Wilkinson1, Peter Crow2, Edward L. Eaton1, and James I. L. Morison1 Matthew Wilkinson et al.
  • 1Forest Research, Centre for Sustainable Forestry and Climate Change, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK
  • 2Forest Research, Centre for Ecosystems, Society and Biosecurity, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK

Abstract. Forest thinning, which removes some individual trees from a forest stand at intermediate stages of the rotation, is commonly used as a silvicultural technique and is a management practice that can substantially alter both forest canopy structure and carbon storage. Whilst a proportion of the standing biomass is removed through harvested timber, thinning also removes some of the photosynthetic leaf area and introduces a large pulse of woody residue (brash) to the soil surface, which potentially can alter the balance of autotrophic and heterotrophic respiration. Using a combination of eddy covariance (EC) and aerial light detection and ranging (lidar) data, this study investigated the effects of management thinning on the carbon balance and canopy structure in a commercially managed oak plantation in the south-east of England. Whilst thinning had a large effect on the canopy structure, increasing canopy complexity and gap fraction, the effects of thinning on the carbon balance were not as evident. In the first year post thinning, the peak summer photosynthetic rate was unaffected by the thinning, suggesting that the better illuminated ground vegetation and shrub layer compensated for the removed trees. Peak summer photosynthetic rate was reduced in the thinned area between 2009 and 2011, but there was no significant difference between sectors. Ecosystem respiration fluxes increased in the thinned relative to the unthinned area in the post-thinning phase.

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Short summary
We measured the exchange of carbon between the atmosphere and a managed oak plantation in the south-east of England for several years before and after a management thinning took place. We also measured changes in the structure of the forest canopy using aerial light detection and ranging (lidar). Whilst management thinning had a large discernible effect on the canopy structure, for example increasing canopy complexity, the effects of thinning on the carbon balance were not as evident.
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