The approach consists of substantive elements that decision-makers and impact analysts need to work through together: 1) the selection of environmental performance indicators; 2) the measures in which impact is to be expressed; 3) the array of alternative interventions for which forecasts should be made; 4) the temporal and spatial bounds and resolution applying to the forecasts; 5) the type of forecasting model used; 6) the sensitivity of performance indicators to specific decision criteria; and 7) the sensitivity of performance indicators to specific uncertainties. The approach was applied in a case study of the effects of the silvicultural use of herbicides on white-tailed deer in a New Brunswick forest.