Fruit trees can offer extensive benefits in the area of nutrition, poverty alleviation and biodiversity conservation in sub-Saharan Africa. A special issue of the journal, New Forests, devoted to “Food Tree Species and Poverty Alleviation” highlights these benefits. World Agroforestry Centre scientist Jules Bayala is co-author of a number of the articles.

The first article looks at how improving basic knowledge about the domestication and preservation of the Baobab tree, Adansonia digitata will benefit use of the species from the farmer to industrial level while also serving as a model for fruit trees in other regions.

Almost all parts of the tree are used and it plays a key role in inexpensively providing the vitamins, minerals and energy that are needed for balanced nutrition in the cereal-dominated diets of people in the dry-zone of Africa. The species has captured the interests of various NGOs and research groups as well as growing commercial interest.

The fruit pulp of A. digitata was approved in June 2008 to be exported as a “Novel species” to the European market and exports are set to increase, providing an opportunity for African farmers to tap into a billion dollar industry.

But, as Bayala and his co-authors point out, improper post harvest handling, post-processing and packing would lead to large losses if done locally.

“Greater attention is needed develop proper protocols for food quality, security and standardization,” says Bayala. ”We also need to make sure that export of the products does not have a negative impact on the villages as the tree provides vital nutrients during drought and when there are cereal shortages. “

Trees constitute a permanent component of the farming systems of sub-Saharan West Africa where they are deliberately selected and maintained. This conversion of natural woodland to farmland or ‘‘parkland” is the traditional agroforestry system of the West African Sahel. During the selection process some species are eliminated while others are retained and this is due to their diverse functions like providing food, medicine, ecosystem services, wood and fuel.

The second article focuses on defining research gaps in order to obtain higher yields and better quality fruits from Sahelian West African fruit trees, including Adansonia digitata, Parkia biglobosa, Tamarindus indica, Vitellaria paradoxa and Ziziphus mauritiana. Among these gaps are strategies for effective management of the genetic resources and a lack of knowledge about key processes of domestication.

A range of domestication activities have been undertaken on these species as they have potential markets both locally and internationally. One of the most challenging aspects is that there are no regional or even national plans for conservation of the genetic resources of the different species, and conservation efforts are not coordinated between countries Another issue concerning all these species is that effective population size, the degree of inbreeding and minimum isolation distance are all unknown. Additional research is needed on pollination biology for most species, and the mating systems and patterns are generally poorly understood.

“Documentation is also something that needs to be considered since a lot of data or trials are never analyzed or published.”

“Great effort is also required to enhance networking and collaboration between national institutions and researchers when it comes to fruit research. This would prevent duplication of research efforts and hopefully increase the impact of breeding programs.”

Bayala says there is also a need to improve the distribution of seeds and plants to famers.

The third article aims to characterize and quantify the tree diversity of parkland systems in Burkina Faso. The scientists highlight how the parklands are degrading due to several factors, including human population pressure, excessive droughts, desertification and farming systems that are oriented towards cash crops that favor monocultures.

“This reduces both the richness and abundance of useful trees and shrubs leaving the rural poor with fewer options to improve their health, nutrition and income.”

“It also means that knowledge is not being transmitted from generation to generation.”
As far as other factors affecting tree diversity in the parklands, land use and farming systems showed a consistently significant effect whereas market access was evident in some cases, for example species richness was significantly higher in villages with little market access. Wealth status did not show any effect on differences in species richness.

Another finding was that tree richness decreased with field age and increased with fallow age. This is as a result of tree selection by farmers in cultivated fields and natural regeneration in fallows. There were fewer tree species in cotton-based farming systems than in cereal-based ones, perhaps because of the need for space for cotton ploughing equipment

Bayala believes the challenge is now for stakeholders and policy makers to integrate gathered knowledge and state of the art knowledge from these and other projects, in coordinated action plan for future utilization, breeding and conservation activities.