Predicting effects of different harvesting intensities with a model of nitrogen limited forest growth

The anticipated increasing utilisation of forest biomass necessitates improved understanding of its long-term consequences on forest productivity. We have used a model of carbon and nitrogen fluxes to predict effects of different management regimes in Norway spruce stands at three levels of fertility. Stands with high production are the least sensitive to intensified harvesting, partly because these stands occur in regions with high nitrogen deposition which compensates for the removal in nitrogen in harvests. Intensified thinning with stem-only removal is the management that affects productivity least followed by whole-tree harvesting at clear-fellings. Whole-tree thinnings are less beneficial and shortened rotation times the least desirable from a production point of view. Increases in total biomass harvests are at the expense of stem harvest, which can mean a conflict between volume and value. The importance of secondary vegetation as is also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.