Health care needs
There is a worldwide trend of increasing demand for many popular, effective species in Europe, North America and Asia, growing between 8-15 percent per year (Grünwald and Büttel 1996). Rapid urbanization and the importance of herbal medicines in African health care systems stimulated a growing national and regional trade in Africa (Cunningham 1993). Demand for medicinal plants also reflects distinct cultural preferences. In the USA, for example, only 3 percent of people surveyed had used herbal medicine in the past year (Eisenberget al.1993), whereas in Germany, with a strong tradition of medicinal plant use, 31 percent of the over-the-counter products in pharmacies in 2001 were phytopharmaceutical preparations (BAH 2002).
The level of herbal medicine use in most developing countries is much higher than this. While most traditional medicinal plants are gathered from the wild, these are not static health care systems, and introduced species are commonly adopted into the repertoire of plants used by African or South American herbalists. In many cases, herbal medicines can also be cheaper than western medicines, particularly where access to traditional healers is easier. Demand for traditional medicine continues in the urban environment even if western biomedicine is available (Anon. 2002b; Manderet al.1997).
Wild harvesting of medicinal plants is a chance for the poorest to make at least some cash income. Especially those people who do not have access to farm land at all depend on gathering MAP to earn at least some money. However, local people generally get a low price for unprocessed plant material. Although income fromPrunus africanabark sales is an important source of revenue to villagers in Madagascar, in some cases generating >30 percent of village revenue, the price paid to collectors is negligible compared to Madagascan middlemen (Walter and Rakotonirina 1995). In Mexico, Hersch-Martinez (1995) found that medicinal plant collectors only received an average 6.17 percent of the medicinal plant consumer price.
Whether fruits, roots, bark or whole plants are involved, the potential yield from wild stocks of many species is frequently over-estimated, particularly if the effects of stochastic events is taken into account. As a result, commercial harvesting ventures based on wild populations can be characterized by a "boom and bust" situation where initial harvests are followed by declining resource availability.
Small-scale cultivation and home gardens
Small-scale cultivation, which requires low economic inputs, can be a response to declining local stocks, generating income and supplying regional markets. This can be a more secure income than from wild harvest which is notoriously inconsistent. For farmers that integrate MAP into agroforestry or small-scale farming systems, these species can provide a diversified and additional source of income to the family. Home gardens are increasingly a focus of medicinal plant propagation and introduction programmes intended to encourage the use of traditional remedies for common ailments by making the plant sources more accessible (Ageletet al.2000).
As outlined byLeakey and Izac(1997), large-scale cultivation has a number of socio-economic impacts on rural people: "Commercialization is both necessary and potentially harmful to farmers. It is necessary in that without it the market for products is small and the opportunity does not exist for rural people to generate income. A degree of product domestication is therefore desirable. On the other hand, commercialization is potentially harmful to rural people if it expands to the point that outsiders with capital to invest come in and develop large-scale monocultural plantations for export markets. Rural people may benefit from plantations as a result of available employment and hence off-farm income [...]. However, plantations may also distort market forces to their advantage, for example, by imposing low wages which will restrict the social and economic development of local people. The major beneficiaries of large-scale exports will probably be the country's elite and, perhaps, the national economy".
Also, those socially disadvantaged groups who actually depend on gathering MAP for their survival and cash income, may not have access to farm land at all and are therefore not able to compete with large-scale production of MAP by well-established farmers (Vantomme in Anon. 2002a). Other limitations to the domestication approach include boom-bust and fickle markets that let farmers down when consumers turn their attention elsewhere (Laird and Pierce 2002).