The effects of removing cloudwater and lowering ambient O 3 on red spruce grown at high elevations in the southern appalachians

Abstract

This study was conducted to determine whether acidic cloudwater and ozone (O 3) 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 O 3 excluded (COE); (2) exposure to ambient O 3 with clouds excluded (CE); (3) exposure to clouds and O 3 (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 O 3 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 occuring at this site elicited reductions in needle Ca and Mg. Ozone had neglible impact on all of the seedling parameters measured.