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5. IMPROVEMENT: enhancing quality and quantity

Forest reproductive material can be improved in many ways - physically, physiologically, genetically and quantitatively. In this section we are concerned with improving both genetic quality and quantity of seeds produced. The physical, physiological and phytosanitary qualities of seeds were mentioned in the topic on HANDLING AND ANALYSING MATERIAL

Any programme of genetic improvement must be built on the correct choice of species and its provenance. Efforts to improve genetic quality of the wrong species and/or poor provenances will be wasted. This has been covered in the page on SELECTING SPECIES AND SOURCES. In its broadest sense, there are three main aspects to the topic of improvement, which are summarised in the table below (which applies to genetic resources in general).

•First, there is the requirement to conserve (protect) genetic variation, and avoid its degradation or loss.

•Second, we can actively improve genetic quality by selection and breeding within our chosen species, provenances, and stands - and

•Third, there is a need to ensure that the genetic material is reproduced in sufficient quantities for planting needs


(from Palmberg-Lerche, C.)





In situ

Protected Areas

Natural forests managed for
productive or protective purposes

Plantations, planted trees
(only occasionally applicable)

Ex situ

Plantations, planted trees

Breeding populations, clone banks,
ex situ
conservation stands

Seed, Pollen, in vitro cultures



Natural forests managed for
productive or protective purposes
(Through silvicultural interventions)

Plantations, planted trees

Breeding populations
Breeding programmes

Improvement and breeding

Plantations, planted trees

Breeding populations,
breeding programmes


Sustainable forest management

Natural forest managed for
productive or protective purposes

Plantations, planted trees

Protected Areas
(only occasionally applicable)

We provide an overview of the key issues and sources of information for these aspects under three groups of activities: (1) the conservation of desirable species and provenances to make sure they continue to be available; (2) the active process of improving the genetic quality of the material by selection and breeding, and (3) techniques to ensure that quantity of the desired material is maintained.


Despite all our efforts, trees and forests continue to decrease in numbers and extent. This inevitably means that genetic variation (which is responsible for a large part of the biological diversity (biodiversity) we see around us) is gradually diminishing (sometimes referred to as genetic erosion). In some cases it is lost forever as species become extinct, provenances are lost, and ecosystems are degraded. As this variation is the essential base for genetic improvement, opportunities to produce trees and forests that provide goods and services that we need now (or may need in the future) are diminishing.

It is therefore essential that we take steps to conserve (protect) forest genetic resources (which includes their reproductive material), putting priority on those resources we know to be most threatened or endangered. In many cases we don't know what those resources are, and it is for this reason that continued plant exploration and taxonomic studies are so important.

See FINDING OUT MORE - SELECTED REFERENCES - CONSERVATION for sources of information on endangered (threatened) species.

Once resources have been identified that are considered valuable and/or threatened or endangered, active conservation can take two forms:

In situ conservation aims to conserve genetic variation where it originated in natural stands within the range of the species or ecosystem. Areas that are sufficiently large to naturally regenerate themselves adequately will be demarcated and managed in such a way as to protect them from further degradation, rehabilitating the forest to its original state where necessary. This will inevitably require provision of some form of immediate benefits, as well as the long-term genetic benefit, and ensuring participation of local communities in helping to protect and benefit from the forest. Forest harvesting and logging carried out as an integral component of forest management, in an environmentally sensitive manner (e.g. in line with Model Code on Forest Harvesting Practice published by FAO is compatible with and contributes to maintaining biological diversity.
(see this publication.) There are different classes of protected area defined by forestry and conservation organisations, depending on their legal status and objectives of management. FAO, IPGRI and DFSC have recently published a technical guide to in situ conservation: “Forest Genetic resources conservation and management: in managed natural forests and protected areas (in situ).

Ex situ conservation aims to conserve genetic variation outside the natural range of the species, as individual planted trees, in clone banks, in seed stands or as reproductive material of different types that are conserved in long-term storage facilities. Although this can be very effective, the amount of genetic variation conserved is limited and it is costly. It therefore needs to be considered as a complement to in situ conservation. New biotechnological methods have the potential for making it easier to conserve larger amounts of genetic variation in this way. Commercial forest plantations as well as tree planting on farms - whose main objective is to produce some form of immediate product or service - can always play a role in conservation of genetic variability, provided any selection and breeding does not reduce variability too much, and appropriate management procedures are properly followed.


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