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5.5 Genetic Improvement
Authors: Rowland D Burdon, GT (Toby) StovoldPublication: NZIF Forestry Handbook, Volume Section 5 – Plantation silviculture, pp 5, Dec 2023
Publisher: New Zealand Institute of Forestry
Abstract: Currently, around 35,000 ha of felled plantation forest per year are being replanted (Forest Owners Association 2018/19). In addition, there are new plantings, which have recently been around 6,000 ha per year and will likely increase under the One Billion Trees programme. All this planting provides opportunities to use genetically improved stock which will upgrade the profitability of the crop. Choice of species is the crucial first selection step in forest tree improvement, particularly in exotic forestry. Differences between species are generally much greater than genetic differences within species. However, the selection of the best geographic races (provenances) for New Zealand can be fully as important for some species. From there comes tree breeding proper (White et al. 2007); it involves the selection of individual trees as seed parents and their interbreeding each generation, to form the basis of recurrent selection. This is how the chosen provenance(s) of a species can be progressively improved, with increasingly improved seed being produced each generation.