Benefits and risks of using clones in forestry - a review
SCANDINAVIAN JOURNAL OF FOREST RESEARCH 2019, 34(5):352-359
Wu, HX

Abstract
The use of vegetative propagation in forestry has a long history. In this chapter of special issue, the genetic gain from clonal forestry relative to family forestry is reviewed. Both theoretical studies and experimental data from progeny and clonal trials indicate that extra genetic gain (5-25%) is possible in conifer from clone testing and deployment relative to deployment of family forestry, effectively doubling that achievable from family forestry within the same generation. There are three perceived risks from using clones in forestry: (1) risk of plantation failure, (2) risk of diversity loss at the forest and landscape levels, and (3) risk associated with success rate of vegetative (or SE) propagation. Three theoretical models are reviewed and described to assess risk and to determine the number of clones required to mitigate these risks. All studies support that a "safe" number of clones is between 5 and 30. Genetic gains and experiences are reported for individual species, particularly in conifers, as well as in Eucalypts. The combination of genomic selection with somatic embryogenesis has the potential to accelerate the development of clonal forestry by shortening clonal testing or omitting long-term clonal testing completely.

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