Forest genetic resources
Conservation and management
Conservation of forest genetic resources is best defined as the policies and management action taken to assure their continued availability and existence. The strategy of conservation and the exact methodologies applied depends on the nature of the material, the timescale of concern, and the specific objectives and scope of the programme. There are two basic strategies for genetic conservation; they are in situ (on site) and ex situ (off site, i.e. in conservations stands, genebanks, arboreta, botanic gardens etc.). These two strategies are complementary and should be carried out in parallel in the case of conservation of species and intra-specific genetic variation. The management of forest genetic resources to ensure at the same time their conservation, improvement and sustainable use is a complex challenge. Fortunately, when simple basic principles are applied, the production of goods and services is generally compatible with the genetic conservation and development of a given forest tree species.
Genetic variation of forest trees, both between species and within species, is today being eroded at an increasing pace, mainly due to changes in land use, and to selection and breeding programmes carried out without sufficient attention to genetic conservation. Large-scale, uncontrolled movement of germplasm and consequent hybridization between local and introduced species and provenances may also lead to genetic contamination and potential loss of local genepools. While changes and some losses in present-day biological diversity over time are inevitable due to both natural and man-made causes, diversity can be conserved with appropriate management.
Photo: Chris Heaman
Neither natural ecosystems nor breeding programmes are static. Genetic conservation should not be aimed at promoting the maintenance of a given state forever but at ensuring the long-term enhancement of the genetic diversity presently available to meet future human requirements. In particular, attention should be given not only to those tree species and populations that are used today, but also to those which may contain variation that will be useful in the future. Since decisions about priorities in the conservation effort will eventually depend on value judgements, collaboration between all stakeholders is needed to identify the values placed by various interested parties on genetic resources, and define appropriate technical and scientific management options.
The management of forest genetic resources to ensure their conservation, improvement and sustainable use is a complex challenge. As a first step, the levels of diversity targeted for conservation and genetic management should be clearly specified. This is of utmost importance as it is possible to conserve an ecosystem and still lose particular species; and as it is possible to conserve a species and lose genetically distinct populations or rare alleles of potential value. Final decisions will depend not only on the extent and patterns of the variation targeted for conservation, but also on the degree of knowledge available on the species, its recognized use and importance, perceived threats and, quite decisively, institutional capacities in countries directly concerned, including infrastructure and availability of funding.
The two main technical options for the conservation of genetic resources comprise conservation in situ and conservation ex situ. These two approaches complement each other. In situ (on-site) conservation implies the continuing maintenance of a population within the community of which it forms a part, in the environment to which it is adapted. Ex situ conservation includes off-site conservation in seed, pollen or tissue banks, in live collections (arboreta, clone banks), or in specially established ex situ conservation stands.
An appropriate combination of in situ and ex situ repositories should be elaborated for each target species. For tree species of limited present use, a network of in situ conservation areas, including production forests and protected reserves placed under varying intensities of management, could be demarcated or established. Such genetic conservation areas, kept large enough to avoid negative effects of inbreeding and genetic drift, should cover central as well as outlying populations.
Forest management for the production of goods and services is generally compatible with the conservation of genetic resources of a given species, provided that some basic, genetic and silvicultural principles are applied. In practice, this means that prevailing forest management prescriptions must be examined in the light of technical guidelines available (see Table 1).
Table 1: Management of genetic resources of forest trees and shrubs: Sub-division by type of area.
FAO and the Danida Forest Seed Centre have actively contributed to the elaboration of technical guidelines for the integration of genetic resources considerations into national planning and forest management practices. For further information, please see:
For further reading on conservation and management:
Poplars in windbreak along roadside. Photo: Bruce Neill/Laura Poppy/Bill Schroeder