Review of wood fuel from early thinning and plantation cleaning in Sweden

Cleaning is carried out in order to influence the competitive situation of controlling the distribution of volume growth and the quality of timber. today, cleaning is conducted on about 200 000 ha per year in Sweden, most if which is cleaned motor-manually. The degree of mechanization is less than 1 % of. The biomass content of a cleaned stand is generally low, ranging from 1 to 2 tons dry matter per ha, but in some stands it can amount to over 20 tons per ha. The main motivation for removing biomass from a cleaned stand is the possibility of reducing overall cleaning costs. Few studies have been made on the environmental effects of the biomass removal in connection with cleaning. Studies made in connection with thinning, primarily conifers, indicate that the negative effects, such as increased soil acidification, reduced pools of base cations and nitrogen losses, can occur. It should be possible to compensate these undesirable effects through measures such as fertilization or ash recycling. Estimates of impacts on the flora and fauna suggests that effects are small and reversible. However, certain biotopes require special attention. Cost and performance studies indicate that it can be profitable for individual landowners to remove biofuel from very tall, dense stands, whereas better technology is required for more commercial operations. The development of such techniques is under way today. For large-scale removal of biofuel in connection with cleaning, simple forecasting tools will have to be developed that can help in determining when and where biomass should be removed. The decision should be based on economic, ecological and technical considerations. Furthermore, thorough analyses of the effects on the nutrient balance need to be made, and any reductions in the quality and growth of timber need to be quantified 21 refs