Browsing by Author "Parkatti, Vesa-Pekka"

This study optimizes the management regime of boreal Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestric L.) stands. The aim is to compare the economic profitability of continuous cover management and clearcut management and to study the hypothesis that continuous cover forestry is more favorable in the case of Norway spruce, compared to Scots pine. Additionally, the study analyses the outcomes of two different growth models for these tree species and compares the results with the requirements of the Finnish Forest Act of 2014. Earlier studies comparing the suitability of Norway spruce and Scots pine to continuous cover forestry have applied unclear model specifications and unnecessary limitations in the optimization methods. In this study, the optimization is carried out using a theoretically sound economic optimization model that determines the choice of the management regime as an outcome of the optimization. The model uses empirically estimated ecological growth models and includes both fixed and variable harvesting costs. Two different empirically estimated ecological growth models are used and compared. The optimization model is solved as a bi-level problem where harvest timing is the upper-level problem and harvesting intensity the lower-level problem. The optimization is solved using gradient-based methods for the lower-level problems and genetic and hill-climbing algorithms for the upper-level problems. This is the first study using this method to solve optimal continuous cover solutions for Scots pine. The results show that the main differences in optimal solutions between the two species are independent of the ecological two growth models used. According to both ecological models, continuous cover forestry is less favorable for Scots pine compared to Norway spruce, in both low and average fertility sites. However, the magnitude of this favorability and the characteristics of the optimal solutions strongly depend on the ecological model. Optimal continuous cover solutions for Scots pine are also found to have very low stand densities. Almost all economically optimal solutions are illegal because of their low number of trees or basal area per hectare.