cipitation in the Sahel and southern Africa (IPCC, 2007). Climate change will particularly affect small islands such as those of the western Indian Ocean, Seychelles, Comoros and Mauritius, and coastal areas.

Many in Africa already experience climate extremes and are vulnerable to the effects of flooding, soil erosion, drought and crop failure (Thomas and Twyman, 2005; IPCC, 2007). The negative effect of these extremes is particularly severe for poor people, who have the least adaptive capacity and are the most vulnerable to climate change (Kandji et al., 2006). Resilience is inhibited by fragile ecosystems, weak institutions, poverty and ineffective governance. Deforestation and changes in land use are other factors that diminish the resilience of agricultural systems, particularly with regard to the availability of ground and surface water (MA, 2005; CA, 2007).

The need to build Africa’s adaptive capacity in regard to climate change is considered a priority by African governments and donor agencies. Methods for coping with short-term climate variation—a proxy for dealing with longer-term climate change—are an important factor driving AKST (Thornton et al., 2006). Rainfall variability is the fundamental factor defining production uncertainty, and while farmers have learned to cope with current climate variability, they are risk averse and are reluctant to make investments when the outcome seems uncertain from year to year (Cooper et al., 2006).

There is a need to establish strong national and regional research centers, particularly for global change research and to identify past initiatives that hold potential but were insufficiently funded. Increasing the number of scientists researching climate change in SSA is a prerequisite for medium- and long-term empowerment in the research arena. This can be achieved by granting doctoral fellowships for young scientists and small grants to assist them in their research. These measures could help limit competition among organizations and avoid redundancy.

Cooperation among climate change initiatives in SSA will be critical in order to disseminate results and avoid duplication of work. Some recent initiatives include the African Monsoon Multidisciplinary Analysis program, which builds scientific capacity through training of trainers programs and supervision of junior scientists, and the Climate Change Adaptation in Africa Research and Capacity Development Program, a capacity building program sponsored by the UK Department for International Development and the Canadian International Development Research Centre (DFID/IDRC).

3.4.1.3 Agroforestry systems
Researchers have been accumulating knowledge for the past 20 years with respect to technologies developed to deal with low soil fertility and land degradation. Their research involves various types of farm experiments such as intercropping legumes and cereals. Some technologies such as hedgerow cropping were not adopted because they required additional labor (Franzel and Scherr, 2002).

More recently, experiments with sequential and improved fallows, which intercrop trees such as Sesbania sesban and Tephrosia vogelii with crops such as maize, have been increasingly successful (Ajayi et al., 2003; Place et al.,

2004). For example, improved fallows of 8-21 months, or one to three seasons, can increase yields two- to fourfold (Place et al., 2004). In eastern Zambia, e.g., 77,500 farmers were known to have adopted tree fallow systems in 2003 (Ajayi et al., 2006). Studies conducted in southern Malawi, eastern Zambia, western Kenya and the humid zones of Mali also show that the highest yields were obtained with repeated application of the recommended rates of synthetic fertilizer.

 Agroforestry techniques that have been adopted with some success include mixed intercropping with Gliricidia, natural vegetative strips, biomass transfers, shaded perennial crop systems and other innovations to improve soil and land management. Yields can increase by two to three times those of current farming practices (Franzel and Scherr, 2002). In western Kenya, for example, managed short-duration fallows have the potential to replace longer fallows in regions where population density no longer permits slow natural fallow successions. The fallows improve crop performance and restore soil fertility and organic matter content in the long term. They use trees such as Tithonia diversifolia and Crotalaria grahaminia in soils where phosphorus is a limiting factor for productivity (Smestad et al., 2002). A gliricidia– maize (Gliricidia sepium–Zea mays) intercropping system has shown that it is a suitable option for soil fertility improvement and yield increases in highly populated areas of sub-Saharan Africa, where landholdings are small and inorganic fertilizer use is low. In these trials, P and K fertilizers were applied and the gliricidia provided N among other benefits (Makumba et al., 2006).

Natural fallows, if done in short rotation, provide poor results, except in some parts of the humid tropics (Hauser et al., 2006). Experiments using legume tree fallows invariably show positive and significant yield increases, except where soils have severely limited P or K or are in arid areas (Mafongoya et al., 2006ab). Here their performance varies, but there are similar results with synthetic fertilizer as well. It remains unclear whether the technology has high potential for adoption or whether it can be repeated without adding other nutrients. It has been consistently found that integrating a tree fallow with small doses of fertilizer is the best option technically and economically. Fallows with herbaceous legumes do not generate as much biomass, and in the case of grain legumes, much of the nutrients are harvested (Mafongoya et al., 2006a).

In the Sahel parklands, indigenous nitrogen-fixing trees, like Parkia biglobosa, Vitellaria paradoxa and Faidherbia albida, have been planted for rehabilitating degraded lands that farmers protect and manage. These areas serve as sources of wood, food, fodder and medicine, and they provide soil fertility for the ecosystem (Teklehaimanot, 2004). Because of pressure on the land, the number of these trees is declining. Vegetative propagation methods, which allow multiplication of superior trees, and on-farm domestication are helping maintain their important role in rural livelihoods.

Fodder shrubs to feed dairy cows have been adopted by about 200,000 farmers in Kenya, Rwanda, Uganda and northern Tanzania over the last decade. Fodder shrubs are attractive to farmers as protein supplements for dairy cows because they require little or no cash expenditure, nor do