Abstract
Red spruce (Picea rubens Sarg.) seedlings were exposed for two growing seasons to ambient ozone (O3) and cloud water deposition at Whitetop Mountain, VA, a high elevation site in the Appalachian Mountains. Native seedlings collected from the site and seedlings grown from seed from the Great Smoky Mountain National Park (GSM seedlings) were used in the study. Field exclusion chambers were used to produce chamber treatments consisting of (1) exclusion of clouds and approximately 50% reduction in ambient ozone (COE), (2) exclusion of clouds (CE), and (3) exposure to clouds and ambient ozone (CC). Photosynthesis of native seedlings was not affected by chamber treatments. GSM seedlings in CC and ambient air plots (AA), however, maintained higher photosynthetic rates than CE and COE treatments into September and October, suggesting that acidic deposition prolonged photosynthesis later into the autumn for CC and AA seedlings. Light response curves of photosynthesis measured in the 1988 and 1989 seasons also showed evidence of higher photosynthetic rates for the September 1988 measurements for CC and AA seedlings, compared to CE and COE treatments. Respiration of previous year needles of native seedlings was enhanced in AA and CC treatments, as was current year needles of GSM seedlings, indicating that O3 and acidic cloud water caused increased respiration in red spruce. Chlorophyll and carotenoid concentrations of needles did not differ significantly throughout the season.
Original language | English |
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Pages (from-to) | 115-124 |
Number of pages | 10 |
Journal | Environmental and Experimental Botany |
Volume | 32 |
Issue number | 2 |
DOIs | |
State | Published - Apr 1992 |
Funding
Acknowledgments This research was supported with funds provided by the Northeastern Forest Experiment
Keywords
- Ozone
- Picea rubens
- chlorophyll
- cloud water
- photosynthesis
- red spruce
- respiration