title: The effects of removing cloudwater and lowering ambient O3 on red spruce grown at high elevations in the southern Appalachians.
abstract: This study was conducted to determine whether acidic cloudwater and ozone (O3) influence the growth of red spruce (Picea rubens L.) seedlings growing at a high elevation site in the southern Appalachian Mountains. A field exclusion chamber study was established at Whitetop Mountain, VA (elevation 1689 m) which included the following treatments: (1) clouds and O3 excluded (COE); (2) exposure to ambient O3 with clouds excluded (CE); (3) exposure to clouds and O3 (CC); and (4) ambient air plots (AA) that served as a control to evaluate possible chamber effects. After 2 years, seedlings exposed to ambient levels of O3 and cloudwater (AA and CC) did not differ in biomass accumulation, diameter growth, or epicuticular wax amounts from seedlings grown in chambers where pollution levels were reduced (CE and COE). Treatments receiving cloudwater (AA and CC) had statistically lower current-year needle concentrations of Ca and Mg, indicating that the cloudwater exposure dynamics occurring at this site elicited reductions in needle Ca and Mg. Ozone had negligible impact on all of the seedling parameters measured.
authors.affiliation: Atmospheric Science Department, Tennessee Valley Authority, Chemical Engineering Bldg., Room 2W 210-A, Muscle Shoals, AL 35660, USA.
authors.forename: F C
authors.initials: FC
authors.lastname: Thornton
authors.forename: C
authors.initials: C
authors.lastname: McDuffie
authors.forename: P A
authors.initials: PA
authors.lastname: Pier
authors.forename: R C
authors.initials: RC
authors.lastname: Wilkinson