Browsing by Subject "rotation forestry"
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(2022)Reindeer (Rangifer tarandus L.) is an integral part of ecosystems across the northern boreal regions, and reindeer husbandry is an important socio-cultural factor, especially for indigenous people. Currently, reindeer husbandry in Fennoscandia is confronted with deterioration of pasture areas, and the decreasing of reindeer number has often been offered as a solution. However, in most reindeer herding districts, forestry has also strongly decreased the sustainable production capacity of winter pastures and therefore has had a significant role in pasture deterioration in addition to high reindeer numbers. The interaction between forestry and reindeer husbandry has often been studied qualitatively, ecologically, or with simple bio-economic models from the perspective of forestry. In this thesis, I use a detailed interdisciplinary ecological-economical model to study how the rotation forestry affects the economics of reindeer husbandry. The research questions are 1) how does the length of forest rotation period and 2) the management practices such as soil scarification and leaving of harvesting residues affect the economically optimal reindeer husbandry. I expand a novel ecological-economical reindeer husbandry optimization model to include the effects of forestry on the ground and arboreal lichen with an assumption of normal forest structure. The effects of forestry on the ground and arboreal lichen are based on previous literature. Modern dynamic optimization algorithms are used to solve the model for the optimal number of reindeer, annual net revenues, lichen biomass on pastures, and the level of supplementary feeding under different forest rotation lengths and management scenarios with zero and positive interest rates. The results show that the length of forest rotation period affects the economically optimal solution. When pasture rotation is used, shortening the forest rotation length decreases the optimal number of reindeer, annual income, and the lichen biomass in pastures, but increases the amount of supplementary feed given. When pasture rotation is not used, shortening the forest rotation length decreases the number of reindeer, annual net revenues, and supplementary feeding, but increases the lichen biomass. Soil scarification and harvesting residues lower the annual net revenues of reindeer husbandry by 1-15% depending on the forest rotation length and pasture rotation. The longer is the forest rotation length, the less the annual net revenues are affected by the forest management practices. Higher interest levels lead to higher reindeer numbers and a higher level of supplementary feeding, but also to lower lichen biomass and annual net revenues from reindeer husbandry. The results of this thesis support the earlier findings of negative effects of rotation forestry and short rotation lengths on reindeer husbandry, and estimations that reindeer husbandry is more resilient if pasture rotation is used. As the economical sensibility of rotation forestry in Lapland has currently been questioned, even-aged forestry could offer a solution with the best management scenarios for both parties. The results of this thesis support infinitely long forest rotation length without soil scarification. This thesis also highlights the need for interdisciplinary co-design of ecological studies to ensure that they are suitable for creating complex interdisciplinary optimization models.
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(2022)Boreal forests fulfil a myriad of ecological, social and economic functions in modern society, which is why it is crucial to manage them in the best way possible. The prevailing forest management strategy in Finland has been rotation forestry, but a Finnish citizens’ initiative and the new EU forest strategy for 2030 have for ecological reasons been calling for a reduction in clearcuts and a switch to continuous cover forestry. While a growing number of economic-ecological optimization studies illustrate the economic aspects of optimal management regime choice in Nordic conditions, the understanding remains incomplete. To contribute to this line of research, this thesis studies the economically optimal management regime and species composition of mixed-species boreal forests with a previously unexamined species combination: Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth). The analysis is based on a theoretically sound and generalized stand-level economic-ecological model that maximizes the net present value of forestry income. In this setup, the optimal management regime is determined endogenously and flexibly, by dynamically optimizing both the rotation period and the timing and intensity of thinnings in a tri-level structure. All model details are empirically estimated. Forest stand development is described by size-structured empirical growth models by Pukkala et al. (2011, 2013) and by Pukkala et al. (2021), of which the latter has not been used in this line of analysis before. The results of this thesis show, for the first time empirically, that it can be economically optimal to conduct near-clearcuts without investing in artificial regeneration afterwards. Near-clearcuts create favourable conditions for utilizing the unharvested young trees and natural regeneration of pioneer species in generating a new tree cohort. This management strategy is found to be suitable for birch-dominated pine–birch stands with a 1% interest rate, as well as pure birch stands. With a 3% interest rate, continuous cover forestry becomes optimal for mixed stands. A further outcome of this thesis is that continuous cover management of pure pine stands is found to be more viable than in previous optimization studies. Further, it is shown that it is economically beneficial to let birch regenerate in a pine stand and even dominate it, due to improvements in overall ingrowth. The characteristics of the optimal solutions are, however, dependent on the ecological growth model used. In light of the cases studied in this thesis, neither rotation forestry nor continuous cover forestry is categorically superior in terms of timber income. There are demonstrably many cases where taking advantage of the environmental benefits of continuous cover forestry and higher tree species diversity is optimal also with respect solely to maximizing timber revenues.
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