in local markets (ICRAF, 1996; 1997). In western Australia, Chamaecytisus proliferus hedges grown on a large scale are browsed by cattle (Wiley and Seymour, 2000) and have the added advantage of lowering the water tables and thereby reducing risks of salinization.

Integrated crop and livestock production can reduce social conflict between nomadic herdsmen and sedentary farmers.

Small-scale livestock producers, especially nomadic herdsmen, follow broad production objectives that are driven more by immediate needs than by the demands of a market (Ayalew et al., 2001). Conflicts between nomadic herdsmen and sedentary farmers have occurred for thousands of years. Nomadic herdsmen in the Sahel have the right during the dry season to allow their herds to graze in areas where sedentary farmers grow crops in the wet season. This leads to the loss of woody vegetation with consequent land degradation, reduced opportunities for gathering natural products (including dry season fodder), and to lowering of the sustainability of traditional farming practices. The development of living fences/hedges to protect valuable food crops and regenerating trees has the potential to enhance production for the sedentary farmers, but unless the nomads need for continued access to wells, watering holes and dry season fodder is also planned at a regional scale, may lead to worsened conflict (Leakey et al., 1999; Leakey, 2003) In this situation, effective integration of crop and livestock systems has to make provision for alternative sources of dry season fodder (e.g., fodder banks), and corridors to watering holes and grazing lands. Participatory approaches to decision making can avoid such conflicts between sedentary and nomadic herdsmen (Steppler and Nair, 1987; Bruce, 1998; UN CCD, 1998; Blay et al., 2004).

3.2.2.1.6 Agroforestry and mixed cropping Agroforestry practices are numerous and diverse and used by 1.2 billion people (World Bank, 2004a), while tree products are important for the livelihoods of about 1.5 billion people in developing countries (Leakey and Sanchez, 1997) with many of the benefits arising from local marketing (Shackleton et al., 2007). The area under agroforestry worldwide has not been determined, but is known for a few countries (Table 3-3). In Africa trees are typically dominant in agriculture in the areas where they are a major component of the natural vegetation (Fauvet, 1996). Agroforestry practices include many forms of traditional agriculture common prior to colonization; complex multistrata agroforests developed by indigenous peoples in the last one hundred years, scattered trees in pastoral systems, cash crops such as cocoa/tea/coffee under shade, intercropping, improved fallows, and many more (Nair, 1989). As a consequence, while the number of trees in forests is declining, the number of trees on farm is increasing (FAO, 2005e). Agroforestry is the integration of trees within farming systems and landscapes that diversifies and sustains production with social, economic and environmental benefits (ICRAF, 1997). Agroforestry is therefore a practical means of implementing

Table 3-3. Examples of land areas under agroforestry.

180% of Indonesian rubber (approximately 24% of world production); Wibawa et al., 2006.

Including jungle rubber (above), durian, benzoin, cinnamon, dammar and others; M. van Noordwijk, World Agroforestry Centre, Bogor.

3Robert Zomer, International Center for Integrated Mountain Development (ICIMOD), Kathmandu.

4Gray Tappan, Science Applications International Corp. SAIC, USGS Center for Earth Resources Observation and Science, Sioux Falls.

5Cissé, 1995; Boffa, 1999.

6Costa Rica, Nicaragua, Honduras, El Salvador and Guatemala; Beer et al. 2000.

7Gaspar et al., 2007

85.9 million ha in West and Central Africa, 1.2 million ha in Asia and 0.7 million ha in South and Central America; P. van Grinsven, Masterfoods BV, Veghel, The Netherlands.

many forms of integrated land management, especially for small-scale producers, which builds on local traditions and practices.

Increased population pressure has resulted in sustainable shifting cultivation systems being replaced by less sustainable approaches to farming.

Throughout the tropics, shifting (swidden) agriculture was the traditional approach to farming with a long forest fallow, representing a form of sequential agroforestry. It was sustainable until increasing population pressure resulted in the adoption of slash-and-burn systems with increasingly shorter periods of fallow. These have depleted carbon stocks in soils and in biomass, and lower soil fertility (Palm et al., 2005b), resulting in a decline in crop productivity. In the worst-case scenario, the forest is replaced by farmland that becomes so infertile that staple food crops fail. Farmers in these areas become locked in a "poverty trap" unable to afford the fertilizer and other inputs to restore soil fertility (Sanchez, 2002).