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Title: Leaf gas exchange along a light graident in a sugar maple forest canopy experimentally exposed to ozone pollution

Abstract

The impact of ozone on leaf gas exchange in a forest canopy as influenced by light environment was studied in a 35-year-old stand of sugar maple (Acer sacchharum) in southern Wisconsin. We developed a chamberless system to expose branches to elevated concentrations of ozone. Ten branches and ten paired controls in the upper canopy (14 to 16 m) were selected along a light gradient, ranging from sunlit (14.5 mol m[sup [minus]2] day[sup [minus]1] PPFD) to deeply shaded (0.6 mol m[sup [minus]2] day[sup [minus]1] PPFD). The branches were exposed for 8 hours each day to ozone concentrations averaging 95 nl 1[sup [minus]1](+/-13 SD), about twice the ambient levels between June and September. Among the branches, area-based rates of light-saturated photosynthesis and dark respiration were positively correlated with mean daily integrated PPFD. Light-saturated rates of photosynthesis and chlorophyll concentrations declined while dark respiration increased with increasing ozone dose. Over time stomatal conductance became uncoupled from light-saturated photosynthesis rates in exposed branches. Photosynthesis and quantum yield were reduced more in a shaded branch than in a sunlit branch in response to ozone treatment. In general, shaded branches were more sensitive to ozone than sunlit branches.

Authors:
; ; ;  [1]
  1. (Univ. of Minnesota, St. Paul (United States))
Publication Date:
OSTI Identifier:
6143414
Alternate Identifier(s):
OSTI ID: 6143414
Report Number(s):
CONF-930798--
Journal ID: ISSN 0012-9623; CODEN: BECLAG
Resource Type:
Conference
Resource Relation:
Journal Name: Bulletin of the Ecological Society of America; (United States); Journal Volume: 74:2; Conference: 78. annual Ecological Society of America (ESA) meeting, Madison, WI (United States), 31 Jul - 4 Aug 1993
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; LEAVES; PHOTOSYNTHESIS; OZONE; BIOLOGICAL EFFECTS; VISIBLE RADIATION; VARIATIONS; AIR POLLUTION; CHLOROPHYLL; FORESTS; MAPLES; RESPIRATION; WISCONSIN; CARBOXYLIC ACIDS; CHEMICAL REACTIONS; DEVELOPED COUNTRIES; ELECTROMAGNETIC RADIATION; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; MAGNOLIOPHYTA; MAGNOLIOPSIDA; NORTH AMERICA; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; PHYTOCHROMES; PIGMENTS; PLANTS; POLLUTION; PORPHYRINS; PROTEINS; RADIATIONS; SYNTHESIS; TREES; USA 560300* -- Chemicals Metabolism & Toxicology

Citation Formats

Tjoelker, M.G., Volin, J.C., Oleksyn, J., and Reich, P.B. Leaf gas exchange along a light graident in a sugar maple forest canopy experimentally exposed to ozone pollution. United States: N. p., 1993. Web.
Tjoelker, M.G., Volin, J.C., Oleksyn, J., & Reich, P.B. Leaf gas exchange along a light graident in a sugar maple forest canopy experimentally exposed to ozone pollution. United States.
Tjoelker, M.G., Volin, J.C., Oleksyn, J., and Reich, P.B. Tue . "Leaf gas exchange along a light graident in a sugar maple forest canopy experimentally exposed to ozone pollution". United States. doi:.
@article{osti_6143414,
title = {Leaf gas exchange along a light graident in a sugar maple forest canopy experimentally exposed to ozone pollution},
author = {Tjoelker, M.G. and Volin, J.C. and Oleksyn, J. and Reich, P.B.},
abstractNote = {The impact of ozone on leaf gas exchange in a forest canopy as influenced by light environment was studied in a 35-year-old stand of sugar maple (Acer sacchharum) in southern Wisconsin. We developed a chamberless system to expose branches to elevated concentrations of ozone. Ten branches and ten paired controls in the upper canopy (14 to 16 m) were selected along a light gradient, ranging from sunlit (14.5 mol m[sup [minus]2] day[sup [minus]1] PPFD) to deeply shaded (0.6 mol m[sup [minus]2] day[sup [minus]1] PPFD). The branches were exposed for 8 hours each day to ozone concentrations averaging 95 nl 1[sup [minus]1](+/-13 SD), about twice the ambient levels between June and September. Among the branches, area-based rates of light-saturated photosynthesis and dark respiration were positively correlated with mean daily integrated PPFD. Light-saturated rates of photosynthesis and chlorophyll concentrations declined while dark respiration increased with increasing ozone dose. Over time stomatal conductance became uncoupled from light-saturated photosynthesis rates in exposed branches. Photosynthesis and quantum yield were reduced more in a shaded branch than in a sunlit branch in response to ozone treatment. In general, shaded branches were more sensitive to ozone than sunlit branches.},
doi = {},
journal = {Bulletin of the Ecological Society of America; (United States)},
number = ,
volume = 74:2,
place = {United States},
year = {Tue Jun 01 00:00:00 EDT 1993},
month = {Tue Jun 01 00:00:00 EDT 1993}
}

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  • Leaf surface patterns of Acer saccharum Marsh were investigated from extremely polluted and relatively unpolluted locations in Montreal, Quebec. In the polluted locations, the values for stomatal frequency were lower, and for trichome density higher than the corresponding values in the relatively unpolluted locations. No variation was evident in the subsidiary cell complex. These patterns may suggest adaptive significance in polluted environments.
  • Two-year old sugar maple seedlings were exposed to charcoal-filtered air (CFA) and to three multiples (1x, 1.5x or 3x) of the ambient ozone (O[sub 3]) concentrations during the summers of 1991 and 1992. The saddled prominent (Heterocampa guttivitta Walker) was reared on leaves sampled from CFA and fumigated plants. Developmental cues such as pupal weight, survival rate, egg production and larval developmental time were measured and compared among CFA and 0, treatments. In 1991, larvae reared on the CFA foliage developed significantly lighter pupal weights than those reared on 1x and 3x (306mg vs 355mg and 353mg); the other variablesmore » were not affected by the treatments. A similar trend was observed in 1992 although pupal weights did not significantly differ among CFA and O[sub 3] fumigations. These results indicate that this lepidopteran can respond to biochemical changes induced by abiotic stresses such as ozone.« less
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  • Long-term monitoring of CO[sub 2] and water vapor exchange is needed to determine components of the carbon and hydrologic cycles and to provide data for parameterizing and testing assessment models. Responding to this need we initiated a continous field measurement campaign in April 1993 in a deciduous forest growing near Oak Ridge, TN. The micrometerological eddy correlation method was used to measure flux densities of CO[sub 2] and water vapor over the canopy. Periodic measurements were made of stomatal resistence and pre-dawn water potential to characterize the photosynthetic capacity of the canopy. Three factors accounted for a disproportionate amount ofmore » seasonal variance in CO[sub 2] flux densities: photon flux densities, leaf area and the occurrence of drought. Positive and increasing magnitudes of carbon gain were observed between April and June as leaves expanded, the canopy closed and daily insolation increased. At midsummer a drought and heat spell were experienced. This period caused CO[sub 2] flux densities to decline. By late summer adequate precipitation and replenishment of soil water resurrected carbon uptake rates until autumnal leaf senescence and leaf fall.« less