Canadian Forest Service Publications
New exposure-based metric approach for evaluating ozone risk to North American aspen forests. 2007. Percy, K.E.; Nosal, M.; Heilman, W.; Dann, T.; Sober, J.; Legge, A.H.; Karnosky, D.F. Environmental Pollution 147: 554-566.
Issued by: Atlantic Forestry Centre
Catalog ID: 27263
Availability: Order paper copy (free)
The United States and Canada currently use exposure-based metrics to protect vegetation from O3. Using 5 years (1999–2003) of comeasured O3, meteorology and growth response, we have developed exposure-based regression models that predict Populus tremuloides growth change within the North American ambient air quality context. The models comprised growing season fourth-highest daily maximum 8-h average O3 concentration, growing degree days, and wind speed. They had high statistical significance, high goodness of fit, include 95% confidence intervals for tree growth change, and are simple to use. Averaged across a wide range of clonal sensitivity, historical 2001–2003 growth change over most of the 26 M ha P. tremuloides distribution was estimated to have ranged from no impact (0%) to strong negative impacts (-31%). With four aspen clones responding negatively (one responded positively) to O3, the growing season fourth-highest daily maximum 8-h average O3 concentration performed much better than growing season SUM06, AOT40 or maximum 1 h average O3 concentration metrics as a single indicator of aspen stem cross-sectional area growth.