Population Pressure, Land Tenure, and Natural Resource Management
Massive degradation of natural resources, including forests, rangeland, and irrigation water, has been taking place in the Third World. Its growing population has increased demand for land, trees, and water, which, coupled with tenure insecurity or the absence of clear property rights, has resulted in the over-exploitation of these natural resources (e.g., Deacon 1994). This in turn has threatened the sustainable development of agriculture, forestry, and livestock sectors. The critical question is whether the current trend will continue and result in further degradation of natural resources and, ultimately, the significant deterioration of human welfare.
Boserup (1965) argued that population pressure need not result in such disastrous consequences. Rather, she argued that it leads to the evolution of farming systems from landusing or natural resource-using systems, such as shifting cultivation, to land-saving and laborintensive farming systems, such as annual cropping.1 Her argument, however, is incomplete: while she acknowledged that investment is required to establish intensive farming systems (e.g., investment in the construction of irrigation facilities, terracing, and tree planting), she paid insufficient attention to incentive systems which ensure that the appropriate nvestments are made. It is widely recognized that investment incentives are governed by the land tenure or property rights institution, as it affects the expected returns to investments accrued to those who actually undertake them (Besley 1995). In sparsely populated areas of Sub-Saharan Africa and islands in the South Pacific, land is often owned and controlled by the community where individual land rights are severely restricted and benefits are shared widely among members of extended families (Johnson 1972). If such communal ownership of land prevails and persists, investment incentives are likely to be weak and thus investments necessary for the intensification of farming systems may not be made (Besley 1995; Johnson 1972). Then, the extensive and natural resource-using farming systems may continue to be practiced, contrary to the Boserupian hypothesis.
Hayami and Ruttan (1985) argued that not only technologies but also institutions change in order to save increasingly scarce resources. This would imply in our context that land tenure institutions change toward individual ownership, so as to provide appropriate investment incentives to conserve natural resources. Consistent with the induced innovation thesis, a theory of property rights institution developed by Demsetz (1967) and Alchian and Demsetz (1973) asserted, based on the historical experience of hunting communities in Canada, that property rights institutions evolve from open access to private ownership when natural resources become scarce. In many parts of Sub-Saharan Africa, it is known that the system of communal property rights on cultivated agricultural fields has been considerably individualized (Bruce and Migot-Adholla 1993). Yet, no systematic research has been made as to the effect of population pressure on land tenure or property rights institutions and the effect of possible changes in land tenure institutions on the investment in land improvement towards the intensification of farming systems and the preservation of natural resources.
Based on the recently completed project concerning land tenure and the management of land and trees in Asia and Africa (Otsuka and Place 2001), this paper attempts to identify the process by which population pressure leads to the individualization of land rights and its consequences on the management of land and trees. Particular focus will be placed on the development of agroforestry systems growing commercial trees, such as cocoa, coffee, cinnamon, and rubber, which are becoming important farming systems in agriculturally marginal areas, where people are particularly poor and natural forests have degraded rapidly (Otsuka 2000).2
The conceptual framework is discussed in the next section, which is followed by the examination of the results of case studies on the management of trees and cropland. Policy implications of this study are discussed in the final section.