View Full Document

An evaluation of ozone exposure metrics



View the full content.
View Full Document
View Full Document

4 views

Unformatted text preview:

Environmental Pollution 117 2002 93 100 www elsevier com locate envpol An evaluation of ozone exposure metrics for a seasonally droughtstressed ponderosa pine ecosystem Jeanne A Panek Meredith R Kurpius Allen H Goldstein Environmental Science Policy and Management University of California 151 Hilgard Hall Berkeley CA 94720 USA Received 1 June 2000 accepted 12 April 2001 Capsule Use of the SUM0 metric sum of all daytime ozone concentrations was only appropriate early in the growing season for ponderosa pine but overestimated ozone uptake under drought conditions later in the season Abstract Ozone stress has become an increasingly signi cant factor in cases of forest decline reported throughout the world Current metrics to estimate ozone exposure for forest trees are derived from atmospheric concentrations and assume that the forest is physiologically active at all times of the growing season This may be inaccurate in regions with a Mediterranean climate such as California and the Paci c Northwest where peak physiological activity occurs early in the season to take advantage of high soil moisture and does not correspond to peak ozone concentrations It may also misrepresent ecosystems experiencing non average climate conditions such as drought years We compared direct measurements of ozone ux into a ponderosa pine canopy with a suite of the most common ozone exposure metrics to determine which best correlated with actual ozone uptake by the forest Of the metrics we assessed SUM0 the sum of all daytime ozone concentrations 0 best corresponded to ozone uptake by ponderosa pine however the correlation was only strong at times when the stomata were unconstrained by site moisture conditions In the early growing season May and June SUM0 was an adequate metric for forest ozone exposure Later in the season when stomatal conductance was limited by drought SUM0 overestimated ozone uptake A better metric for seasonally drought stressed forests would be one that incorporates



Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view An evaluation of ozone exposure metrics and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view An evaluation of ozone exposure metrics and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?