Policy Implications

First and foremost, modeling approaches such as those involving the estimation of steady state or dynamic critical loads could be of benefit to policy makers when evaluating the possible consequences of various pollution mitigation options as they relate to Ca cycling, forest health, and productivity. Analyses of trends in data from the field have been used to evaluate whether implementation of Phase I of the Clean Air Act Amendments of 1990 resulted in sufficient reductions in pollutant inputs to protect environmental resources, (e.g., Butler and others 2001, Likens and others 2001). However important, this retrospective approach does little to inform decision makers of the possible future or long-term impacts of pollutant deposition. In contrast, a noted benefit of critical loads and associated forest sensitivity modeling is the flexibility provided to project trends forward and estimate the location and extent (steady state) and timing (dynamic models) of pollution-induced impacts. Furthermore, these models can be used to estimate differences in pollution loads and impacts among various pollution reduction plans, thereby allowing for a more detailed and reasoned analysis among policy alternatives.