This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends sustainable mountain development as part of an overall programme for managing fragile ecosystems.
An agroforestry farming system in the highlands of Papua New Guinea has been developed by village growers since about 1960 and has expanded rapidly since about 1970. Major components of the system are numerous species of annual and perennial food crops (especially bananas), arabica coffee and [Casuarina oligodon]. It provides food, a cash crop and timber for construction and fuel. It is likely that returns on labour inputs are very favourable, but no formal assessments have been made. Evaluation of the system as a whole, and research on certain key components (casuarina ecology, banana cultivars, timing of operations) are suggested as high priority areas for systematic studies.