© 2000 Heron Publishing—Victoria, Canada
Managing forests for wood yield and carbon storage: a theoretical study
J. H. M. Thornley (1) and M. G. R. Cannell (1)
1. Institute of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian EH26 0QB, U.K. / Received August 24, 1999
Summary
Which forest management regimes best achieve the dual objectives of high sustained timber yield and high carbon storage, including
the carbon stored in soil and wood products? A mechanistic forest ecosystem simulator, which couples carbon, nitrogen and
water (Edinburgh Forest Model), was calibrated to mimic the growth of a pine plantation in a Scottish climate. The model was
then run to equilibrium (1) as an undisturbed forest, (2) removing 2.5, 10, 20 or 40% of the woody biomass each year (3) removing
50% of the woody biomass every 20 years, and (4) clear-felling and replanting every 60 years as in conventional plantations
in this climate.
More carbon was stored in the undisturbed forest (35.2 kg C m–2) than in any regime in which wood was harvested. Plantation management gave moderate carbon storage (14.3 kg C m–2) and timber yield (15.6 m3 ha–1 year–1). Notably, annual removal of 10 or 20% of woody biomass per year gave both a high timber yield (25 m3 ha–1 year–1) and high carbon storage (20 to 24 kg C m–2). The efficiency of the latter regimes could be attributed (in the model) to high light interception and net primary productivity,
but less evapotranspiration and summer water stress than in the undisturbed forest, high litter input to the soil giving high
soil carbon and N2 fixation, low maintenance respiration and low N leaching owing to soil mineral pool depletion.
We conclude that there is no simple inverse relationship between the amount of timber harvested from a forest and the amount
of carbon stored. Management regimes that maintain a continuous canopy cover and mimic, to some extent, regular natural forest
disturbance are likely to achieve the best combination of high wood yield and carbon storage.
Keywords:
carbon, forest, management, model, nitrogen, plantation, productivity, volume yield.
