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LOW-COST VEGETATIVE PROPAGATION AND FORESTBIODIVERSITY CONSERVATION
By Ronald Bellefontaine
The low-cost vegetative propagation of multi-purpose tree species can contribute to at least four of the UN Millennium Development Goals, i.e. the eradication of extreme poverty (MDG1), promoting gender equality and empower in women (MDG3), combating HIV/AIDS, malaria and other diseases (MDG6), and ensuring environmental sustainability (MDG7). In many countries, certain multi-purpose tree species are becoming rare and threatened with local extinction. These species frequently provide a combination of the following: food, medicine, fuel, fodder, wood, and income through sale of products. As women are usually in charge of producing food and medicinal plant items, mastering vegetative propagation of those species important to them provides women with greater control over their family’s welfare. Targeted promotion of these techniques can thus help promote food security, local health care, and enhance income, while empowering women.
Sustainable forest management, and conserving biodiversity of farmlands, pastoral areas and woodlands can contribute to reversing the loss of environmental resources (MDG7). Vegetative propagation can play an important role here. Multi-purpose tree species can help meet the demand for wood and non-wood products while contributing to biodiversity. This is particularly true in areas with very low forest cover, such as fields, pastoral land or small plantations. Regenerating a variety of local tree species can help maintain or revive local biodiversity, and create a habitat for other plants and animals. When large areas of woodland have been cleared for cropping, the negative impact of the clearing process on the area’s biodiversity may be reduced by encouraging the community to propagate useful species around the edges of the fields and in other areas not suitable for arable farming. Many tree species found in open woodlands and outside forests have a good potential for root suckering, root cutting or ground layering. Compared with sexual reproduction, these vegetative propagation techniques have important socio-economic advantages such as their low cost, the availability of labour just before the rainy season, reduced hole-digging (and subsequent erosion), and the reproduction of trees with physical characteristics preferred by farmers .
Despite the fact that the survival rate of seedlings is usually very low, the strong sprouting capacity and sucker producing potential of many tropical tree species is currently barely used in sustainable forest management plans. Pre-logging inventories tend to include only seedlings and stump sprouts, while root suckers and layering are rarely considered as possible propagation techniques (Bellefontaine 2005a). Trees can colonize ecosystems by producing adventive stems from the root system and from branches and trunks. Stress caused by, for instance drought, fire, or ploughing may induce a tree to produce sprouts from the basis of the stem (basal sprout, root crown), from its branches (layer, rhizome, runner) or from its roots (sucker). Sometimes, this appears to be the only way that trees growing in harsh environmental conditions (such as droughts, cold temperatures, seasonal flooding, natural range limits, forest fragmentation) can propagate themselves. Rural people could benefit from the root cutting method by propagating additional trees at a low cost for medicinal, foliage or fruit purposes. Two groups, the Legumes (Rhizobial plants) and Actinorhizal plants, can thrive without any fixed nitrogen or with a minimal supply in the soil. Propagating trees from root cuttings would overcome the problem of introducing the root fungus (or bacterium for Legume trees) in order to get them to grow successfully. It would therefore make sense to try and grow trees from roots.
Vegetative propagation techniques, and their potential to contribute the MDGs, merit attention as their social and economic viability is promising. But many technical and scientific questions still remain. Local tree-tending practices are based on empirical knowledge that is rarely documented. People in different countries may have developed their own successful methods of terrestrial layering, root suckering or root cutting. Women are often especially knowledgeable of the vegetative propagation potential of certain tree species. There is now an urgent need to document, study and disseminate this local and traditional knowledge.
References:
Further information:
Ronald Bellefontaine
CIRAD - Forest Department
34 398 Montpellier Cedex 5
France
Email: ronald.bellefontaine@cirad.fr