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The nonrenewable-with-backstop model of resource management is extended to cover renewables and applied to the case of coastal groundwater. In the optimal management trajectory, efficiency price exceeds extraction cost by the sum of scarcity rent and “drawdown” cost, the latter remaining large even after the backstop price is reached. In the case of rising demand, optimal management may call for a stage of conservation followed by a stage of drawdown. Copyright 1997, Oxford University Press.

Once established, invasive species can rapidly and irreversibly alter ecosystems and degrade the value of ecosystem services. Optimal control of an unwanted species solves for a trajectory of removals that minimizes the present value of removal costs and residual damages from the remaining population. The shrubby tree, Miconia calvescens, is used to illustrate dynamic policy options for a forest invader. Potential damages to Hawaii's forest ecosystems are related to decreased aquifer recharge, biodiversity, and other ecosystem values. We find that population reduction is the optimal management policy for the islands of Oahu, Maui, and Hawaii. On the island of Kauai, where tree density is lower and search costs higher, optimal policy calls for deferring removal expenditures until the steady state population is reached.

Mitigating the harmful effects of development projects and industries (negative environmentalism) is inadequate, especially in resource-dependent economies whose resources are at risk from other forces. While positive environmentalism includes conservation projects, the non-market benefits of such projects are difficult to evaluate. This paper provides and illustrates a method for evaluating the indirect, watershed benefits of a tropical forest, without resorting to survey methods. The conservation of trees prevents a reapportionment from groundwater recharge to runoff that would otherwise occur. The value of the water saved is then valued at the shadow prices obtained from an optimizing model. An illustration of the model shows that watershed conservation projects may have very high payoffs, even before assessing existence values and other forest amenities.

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