MES Capstone Summary
Beth Gingold
Master of Environmental Studies, University of Pennsylvania, May 2007

The provision of an adequate supply of clean water for competing uses is becoming increasingly difficult in Puerto Rico. The growing population, urbanization and industrialization has led to increased water consumption and increased competition for the island’s limited water supply. At the same time, sedimentation of the island’s reservoirs has led to decreased storage capacity, and contamination of groundwater has led to decreased aquifer withdrawals (Hunter and Arbona, 1995).

Effective land use policy must weigh both the private and public costs and benefits of converting forests to alternate land uses. This project assesses the private and public impacts of forest to pasture conversion in the montane regions of Puerto Rico. In many tropical montane areas, forest conversion to pasture is a financially profitable land use option for landowners. At the same time, this change in land use has consequences for the public provision of ecosystem services, including the quantity and quality of water available to downstream users. These public consequences are often assumed to be negative, and there are many programs in the tropics designed to promote forest conservation. However, the scientific and economic literatures suggest that forest conversion to pasture may have both positive and negative impacts on public benefits. This project provides insight into conditions under which conversion from forest to pasture may be socially optimal by evaluating the hydrologic externalities associated with forest-to-pasture conversions in the humid subtropical lifezone of Puerto Rico.

In Puerto Rico, as in many other parts of the tropics, forest conservation provides public benefits. In particular, due to Puerto Rico’s dependence on reservoirs for its water supply, erosion control is a socially valuable function of forests. The idea that forests provide public benefits has been used to justify public spending on forest conservation. However, the conversion of forests to pasture not only results in private benefits to the landowner, but in some cases may provide public benefits greater than the costs of increased erosion. Other ecosystem services provided by forests may be significant enough to outweigh the private benefits of pasture in some areas, but not in others. It is important for policy-makers to consider such trade-offs and recognize the importance of site-specific variables and appropriate targeting when designing land use policies.

For an extended description of methods and results, including data collection and model information, please see full capstone.

Table 4.1.16. Private and public costs and benefits of subtropical wet forests in Puerto Rico. Unless otherwise stated, all units are in $/ha/yr. Range of values reported in literature for tropical forests (Almeida and Uhl, 1995; Aylward and Echeverría, 2001; Pearce, 2001; Aylward, 2002) compared with estimates compiled for subtropical wet forest zone in Puerto Rico.

Photo courtesy of Beth Gingold.

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