Development of economic forest tree breeding objectives

Sammanfattning: The overall objective of this thesis was to suggest a framework for developing forest tree breeding objectives with particular emphasis on boreal conditions and, as components of this framework, to define breeding objectives and calculate economic weights based on two case studies of Scots pine in northern Sweden. The framework was designed to take into account boreal conditions, with long rotations, heterogeneous raw materials and a diverse production system. It is suggested that the forest products industry should be divided into subsectors, each representing a particular industrial segment. For each subsector the production system studied should consist of a vertically integrated structure, with the aim of maximising profit, and in which all costs are considered variable. In addition, appropriate objective traits should be applicable over a wide range of site conditions, silvicultural regimes and industrial subsectors. The first case study examined how to calculate the economic weight of tree survival relative to volume production, taking patchiness into account. For this purpose a new model was developed and then applied to field data in order to obtain relative economic weights for a set of Scots pine breeding populations in northern Sweden. The relative economic weight of survival varied markedly between the studied breeding populations, increasing more than three-fold with decreasing survival and increasing patchiness. The second case study defined a breeding objective for a vertically integrated company in northern Sweden, which cultivates forests and supplies its own sawmill. Results showed that a compound growth indicator (height and diameter) was a very important selection criterion, while a wood density indicator was of moderate value and vitality and straightness indicators were of negligible value. The framework can be adapted to determine economic weights appropriate for a boreal forest sector with a diverse production system and can also act as a platform to assist strategic breeding decisions when there is uncertainty within the system. Within the framework, analyses may combine several different scenarios, for which subsectors can be allocated different sizes that represent their future relative importance based on predicted supply and demand.

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