生物多様性管理と林業ジャーナル

Cost-Efficiency of Alternative Forest Conservation Targets, a Case Study from Finland

Anssi Ahtikoski, Riitta Hänninen, Jouni Siipilehto, Jari Hynynen, Juha Siitonen, Terhi Koskela and Soili Kojola

Temporal contracts to protect biodiversity in forests are a recent approach which has shown to be a promising and cost-efficient procedure. With respect to cost-efficiency of temporal contracts the relevant issue is the goal of conservation: for instance, are we interested in enhancing CWD index (coarse woody debris) or increasing the amount of dead wood in forests? This study focuses on demonstrating the effect of conservation goal (either enhancing CWD index or increasing the amount of dead wood) on costefficiency by optimization. Further, we analyze whether both the length of temporal conservation (10 or 30 years) and discount rate (2% or 4%) would have an effect on optimal solutions. The data consisted of 20 measured forest sites with stand age between 60 and 160 years. Majority of the stands (80%) fulfilled the biological conservation criteria of the Finnish Forest Biodiversity Programme METSO and a few of the stands were managed commercial forests. For temporal conservation (either 10 or 30 years), stand growth and dynamics of decaying wood were forecasted with a stand simulator (Motti) by prolonging the clear-cut with 10 or 30 years. The results for the two alternative conservation periods were compared to business-as-usual, BAU, with respect to income losses. Then, for ecological responses the initial, measured stand characteristics were set for the baseline to which temporal conservation alternatives (10 or 30 years) were compared to. The results of optimization distinctively demonstrated that the conservation goal has a relevant effect on the cost-efficiency. Further, the length of the conservation period has also an important role in cost-efficiency whereas the discount rate plays only a minor role in this study context. In the optimal solutions the forest sites with distinctively above-average initial amount of dead wood and excellent growth predictions which imply lower than average income losses due to conservation shone through with respect to cost-efficiency. As a word of caution, it should be pointed out that if one merely chooses the most cost-efficient sites for conservation, there is a possibility that a desirable level of biodiversity might not be fulfilled. To test this, the study needs to be next extended to landscape level with larger data input.