Forests and Trees
- Overview
- A forester climbs a tree (Prunus africana) in Kenya.Credit: L. Thomson
Forest genetic diversity is usually taken to represent the genetic variability within tree populations and species. However, sometimes a broader definition is adopted that includes genetic variability present in all plants, animals and microbes found in forests.
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Diversity within tree species
Forest tree species are typically long-lived and have developed natural mechanisms to maintain high levels of genetic variation within species. These include high rates of outcrossing and the dispersal of pollen and seeds over wide areas. These mechanisms, combined with native environments that are often variable have contributed to the evolution of forest tree species into some of the most genetically diverse organisms in existence.
New research is revealing that forest community ecosystem processes, including evolution of biodiversity, are closely related to the genetic diversity in structurally dominant and keystone tree species.
Why genetic variation in trees is vital
Forest and tree genetic resources are associated with the genetic diversity present in thousands of useful and potentially useful forest tree species on earth. They constitute an intergenerational resource of vast social, economic and environmental importance.
From a biological viewpoint, genetic variation is needed to ensure present-day and future adaptability of species as well as their continued evolution. From a human and development perspective, variation is also vital to maintain options and potential for genetic improvement to meet changing end use requirements and dynamically evolving environmental conditions.
For many poor people living in tropical regions, forest and tree genetic resources are not just a matter of economic (in monetary terms), cultural, spiritual, recreational or ecological and scientific value. They constitute a capital inheritance that, until recent times, was passed on, relatively intact or in some cases enhanced, by past generations to current generations. Together with other plant and animal genetic resources, forest and tree genetic resources are the capital needed for development and maintenance of rural communities and upon which almost all rural income (both cash and non cash) is derived. Sustaining progress in rural development, and enhanced livelihoods for the poor, will require improved access and availability to diverse germplasm of indigenous and introduced tree species.
Making good use of forest and tree genetic resources
The high levels of genetic variation that are present within many tree species can be beneficially developed and used by foresters and tree growers. Whereas agricultural crop breeders and farmers often substantially modify the growing environment to suit a specific crop species or variety, tree growers commonly identify species and provenances which can provide some improved levels of the goods and services required even without intensive selection and improvement, or intense management requirements, or major modification of the external environment.
Such diverse tree genetic materials are, moreover, intrinsically well buffered against variations in soil and microclimates when deployed locally. Accordingly, forestry and agroforestry production systems depend considerably on the continued availability of these diverse genetic resources at both the species and provenance (population) levels.
Intraspecific genetic variation is needed to ensure the future adaptability of the species, as well as allowing for domestication and breeding programmes. Accordingly, benefits from forests and trees will only be sustained if forest genetic resources remain available. In many countries, the prospects for successful and sustainable rural development will be greatly influenced by the availability of genetic diversity in both indigenous and exotic tree species.
Status of conservation of forest and tree genetic resources
In terms of our understanding of conservation of individual tree species, we have variable knowledge, usually limited and often with no knowledge of the distribution, frequency and threats to many tropical tree species. The best estimate is that over 8 000 tree species, or 10 percent of the world's total, are facing extinction. The majority of these tree species occur in tropical forests and many have important socio-economic values for local human populations.
Knowledge of conservation of forest biodiversity at the gene level is even less well documented and understood than for species. There are major threats to the integrity of forest genetic resources from a myriad of causes. These include deforestation and changes in land use; inappropriate forest use and management practices including overharvesting; pollution and climate change; invasive species, and the undocumented and poorly regulated movement of tree germplasm.
Dynamic conservation
Conservation and sustainable use of forest and tree genetic resources may be considered as the actions and policies that assure the continued existence, evolution and availability of these resources for present and future generations. Both the genetic resources themselves and the practice of their conservation are essentially dynamic processes.
Accordingly, the conservation of these resources should not be seen as an attempt to preserve a particular group of genotypes or populations, and their various combinations of genes. Rather, the aim of genetic resource conservation and management is to maintain conditions in which the genetic makeup of species can continue to evolve in response to changes in its environment. At the same time, management for conservation aims at reducing the rates of genetic erosion.
Bioversity's work on forest genetic diversity
Bioversity's Forest Genetic Diversity project addresses the challenges associated with the conservation and sustainable use of wild and semi-domesticated tree species. These species typically exist in forests which are under some form of communal ownership or which may have open-access to resources.
The objectives of Bioversity's research on forest genetic diversity are to contribute to ensuring that the diversity of forest and tree species are better understood, conserved, and more effectively and widely used, and the benefits derived from these resources and their diversity more widely recognized. Ultimately, the objectives are to encourage forest and land managers, planners and others whose activities have an impact on forest genetic resources, to routinely consider gene conservation and sustainable use in their planning and management processes, taking into account different levels of threats, patterns of land use, forest management practices and future selection and breeding programmes.
The Forest Genetic Diversity Project aims to achieve its objectives through generating knowledge, tools and methodologies for conserving and using forest genetic resources, through strengthening institutional frameworks and contributing to international research collaboration and policy-making. This includes efforts to locate and monitor genetic diversity in forest ecosystems, identify combined in-situ and ex-situ strategies for the conservation of selected species, contribute to the conservation and awareness of the value of diversity among non-timber forest products, build capacity among partners for forest genetic resources conservation, and work to develop regional programmes on forest genetic resources.
The Forest Genetic Diversity Project is carrying out research in partnership with national and international partners, contributing to the formulation of global forest genetic resources policy. It works with and through regional forest genetic resources networks, the European Forest Genetic Resources Programme (EUFORGEN), the Sub-Saharan African Forest Genetic Resources (SAFORGEN), Asia Pacific Forest Genetic Resources Programme (APFORGEN)and Latin American Forest Genetic Resources Programme (LAFORGEN) to promote partnership to address common problems through collaborative research and training.
