Forest Tree Breeding and Genetic Diversity of Wood Species

Abstract

In scientific literature there are different views on the connection between forest tree breeding and genetic variability of wood species. This article has aimed to review the current Russian and foreign literary sources on the impact of breeding measures on the level of genetic diversity of forest wood species. Maintaining adequate genetic variability is necessary for adaptation to the environmental changes, as well as for long-term breeding. As soon as seed plantations are the source of improved seeds for forest regeneration, the influence of such factors as the number of clones and background pollination on the level of genetic variability of the progeny has been considered in detail. The data on the minimal clone number in seed plantations in different countries has been presented and the variability of the clones based on their fertility has been discussed. The importance of background pollination in seed plantations has been highlighted as soon as, on the one hand, it reduces the effect of breeding, but on the other hand, it increases the level of genetic variability of the progeny. A decline in genetic diversity of wood species can be caused by clone selection (which is the basis for clonal forestry). However the analysis of literary sources has shown that the reduction in genetic diversity is minimal if scientific recommendations are fulfilled. The use of the seeds from controlled cross-breeding of plus trees selected as a result of genetic evaluation (the so-called family forestry with vegetative propagation) in the somatic embryogenesis of the common spruce increases the level of genetic variability of the progeny. It has been shown that the multiple population breeding system allows to combine intensive long-term breeding and genetic conservation of wood species. The conclusion has been drawn that the implementation of optimally planned wood species breeding programs does not lead to significant narrowing of genetic diversity. On the contrary, forest tree breeding contributes to the preservation of a better gene pool, transmitting it in the process of forest regeneration through improved seeds and clones into homogeneous stands. Moreover, the objects of forest seed growing such as the archives of plus tree clones and forest seed plantations, as well as test cultures contain valuable genetic material ex situ.