People who rely very immediately on natural resources for their livelihood have always developed methods to ensure the conservation of their environment. In general, these methods are more explicit and more formalized in situations where resources are very scarce, such as in arid lands, although implicit rules governing resource use exist as well in situations of relative abundance. On the community level, resource management systems have generally been more evident among the disadvantaged and rural dwellers than among the urban rich, simply because means of livelihood other than direct resource exploitation are less readily available to the former groups. Such traditional resource management systems, in spite of the external and internal pressures which will be discussed below, have remained not only viable, but also active and evolving in many parts of the world. Where still extant today, these systems involve elaborate social, technological, and economic mechanisms to safeguard resources.

There are numerous descriptions, for instance, of religious or spiritual significance being attached to certain plants or animals, which are thereby protected. A particularly striking and well-documented example comes from India, where the religious beliefs held by the Bishnoi community have prohibited killing animals or cutting green trees since the fifteenth century. Today, Bishnoi land is a green and flourishing area in the midst of the surrounding Rajasthan desert (Sankhala and Jackson, 1985). There are many similar examples of centuries-old environmental reserves, specifically declared as such (Draz, 1985; Farvar, 1987). More common, however, are customs prohibiting the exploitation of particularly useful species, such as the peepal tree in Asia or the baobab in Africa, or allowing the harvesting of animals or plants only at certain seasons or otherwise under conditions which minimize damage to their reproductive potential (Gadgil, 1985; Tobayiwa, 1985).

Social controls have also been developed in many communities explicitly to regulate resource use and to ensure that the environment is managed sustainably. The intricate mechanisms governing pastoralists' grazing patterns, and the intimate environmental knowledge upon which such mechanisms are based, have been well-documented (Lane, 1990). Herds are moved according to land use rules which prevent either the most productive or the most drought resistant lands from being overgrazed. Social convention similarly governs the use of water in the communal irrigation management systems which have existed for centuries in several parts of Asia (Farvar, 1987; Yabes, 1991), while means of restricting use rights over marine, agricultural and forest resources have enabled communities in various parts of the world to sustain their resource base (Polunin, 1985; Baines, 1989; Moorehead, 1989; Diegues, 1990).

In addition to communities which have well-defined and explicit rules governing resource use, there are many situations in which resource use regulations only become evident to outside observers when overexploitation threatens to degrade the resource base. For instance, in many Pacific island communities, marine resources are seemingly harvested under open-access conditions: there are few stated general rules limiting access, and if local residents are questioned about any such regulation they may say that all are free to fish as they like. However, as Hviding (1990) points out in a study of a Solomon Islands community, when resource extraction exceeds certain limits – commonly associated with the commercialization of fishing – marine tenure traditions begin to exert their force, and social sanctions limit the overexploitation by local residents of any particular area or species.³ Similarly, the complex tenure and usufruct patterns of rainforest extractivists and shifting cultivators have recently been described (Colchester, 1989). The existence of these invisible (to outsiders) or latent traditional management systems means that caution must be taken before judging any particular resource to be unregulated.

A third institutional mechanism increasing the sustainability of traditional resource use is the development, refinement and transmission of environmental knowledge in rural communities. Although often dismissed as "intuitive", indigenous knowledge has in fact been distilled over centuries and is often the best guide to sustainable resource management. Perhaps the most striking and well-known example of a community which has an incredibly detailed knowledge of the plants, animals and soils of its environment, as well as of the best means of managing its resources in order to compensate for soil deficiencies, is the Kayapo of the Amazonian basin (Hecht, 1989; Cummings, 1990; Hecht and Cockburn, 1990). Although the complexity of the ecosystem of the Amazon makes the Kayapo case particularly impressive, in fact, detailed indigenous environmental knowledge is the rule rather than the exception in most traditional Third World societies (Johannes, 1981; Ravnborg, 1990; Amanor, 1990).

3 More active sanctions have been used to combat commercial intrusions from outsiders, ranging from sabotage and assault to the imprisonment of a U.S. fishing boat captain and the impoundment of his vessel.