Cost-effectiveness of measures to improve biodiversity in Swedish forests

Abstract: The main objective of this thesis is to analyse the cost-effectiveness of measures, which improve biodiversity among life forms dependent on coarse woody debris (CWD). The amount of CWD in forest land has decreased due to modern forest management. The wood of the trees is an important source of income for the forest owner and there is an undeniable conflict between increasing the amount of CWD and the economics of silviculture. To gain acceptance among forest owners of an increased retention of trees as potential CWD substrate, it is important that CWD-increasing measures are performed in a cost-effective manner, which means that the cost to attain a specific level of CWD is as low as possible. Calculations were performed of CWD formed and opportunity costs of forest stands from three regions in Sweden. Norway spruce was the prime study object but analysis of mixed stands of Norway spruce, Scots pine and birch or aspen were carried out as well. The cost-efficiency of seven conservation measures, which aim to increase CWD in managed forests, was analysed. In all regions the same pattern was obtained regarding ranking order of five measures; retention of snags was the most cost-effective measure, followed by creating high stumps, manual scarification and retention of living trees, and finally prolongation of rotation as the least cost-effective measure. Setting aside a stand as a reserve, and retention of wind-thrown trees showed an increasing cost with increasing land productivity. Estimating the cost-efficiency factor for different CWD-increasing measures in mixed stands revealed that birch and aspen were more cost-effective than Norway spruce and Scots pine. In a multiple stand context the least-cost allocation of conservation measures depends on the desired increase in CWD. Analysing the choice of cost-effective CWD-increasing measures on a Norway spruce dominated estate in central Sweden showed that huge improvements in the cost-effectiveness of biodiversity-oriented forestry are possible.