Expert Opinion Survey on the Impacts of Air Pollutants on Forests of the Usa

.A panel of experts was surveyed to obtain subjectix-e estimates of the current impact of five air pollutants (SO,, NO,, O,, H,SO,, and HNO,) on srowth, mortality, and leaf area of forests of the continental U . S. for later input to economic analysis. Results from the first two of three questionnaires are discussed. Estimates of impact were highly variable among panelists (CV's near l o o % ) , but identify forest types at risk. Southern California conifers and high elevation spruce-fir were perceived most damaged with 1 0 and 12% median growth reductions. Sout.hern pines, southern hardwoods, northern hardwoods and low elevation spruce-fir were equivalent with 5% reductions. Median impact for other western conifers was 0%. Ozone was perceived the most damaging pollutant in each of the seven forest types investigated, with damage by the two acidic pollutants like15 limited to the high elevation spruce-fir. The amenity-related leaf area and mortality measures were less familiar and more volatile. Implications of pollutant interactions, temporal stability, and panel selection are also discussed.