The challenge and opportunity of applying ecological thresholds to environmental assessment decision making
Chris J. Johnson, Justina C. Ray
Abstract
The threshold concept is commonly invoked as a necessary component of environmental assessment and, more broadly, land-use decision making. Many consider thresholds as objective and finite stopping points at which a harmful activity or development trajectory should cease, because further activities will result in an unacceptable change or risk to the environment. Although ecological thresholds can play an important role in environmental assessment, they are not a simple solution to complex socioecological decisions, nor do they ensure objective decision making. A threshold, even if precise, is only one component of the assessment process. In contrast to the often naive expectation of precise and definitive science-based thresholds, management or significance thresholds recognize a continuum of risk that can be weighed against socioeconomic interests. That risk continuum can guide the incremental increase in monitoring and precaution that should accompany the review and implementation of individual projects or land-use change that results in cumulative effects across watersheds.