Proportional-plus-integral control of experimental ozone concentrations in a large open-top chamber

Dean, Thomas J.; Johnson, Jon D.

doi:10.1016/0960-1686(91)90152-w

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…Ozone was produced using a Griffin ozone generator (Griffin Technics, Lodi, New Jersey, model GTC-2A) running on pure oxygen. Daily exposure from 08.00 to 20.00 h was computer controlled to follow natural diurnal and seasonal fluctuations in ambient ozone concentrations (Dean & Johnson, 1991). Further details of the exposure system have been published (Byres et al 1992).…”

Section: Treatmentsmentioning

confidence: 99%

Seasonal response of slash pine (Pinus elliottii var. elliottii Engelm.) photosynthesis to long‐term exposure to ozone and acidic precipitation*

1992

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summary Four half‐sib families of slash pine (Pinus elliottii var. elliottii) were planted in open‐top chambers and exposed to ozone and simulated acidic precipitation (3: 7 molar ratio of nitric and sulphuric acids). The 4 ozone treatments were (1) charcoal‐filtered air, (2) unfiltered ambient air, (3) twice ambient and (4) three times ambient ozone, with treatments applied 12 h per day, 11 months per year for 28 months. Seedlings were irrigated weekly with one of three rain acidities: pH 33, 4.3 or 5.3 at a total rainfall equivalent of 133 cm per year. Photosynthetic rates were measured approximately every 10 weeks, on the most recently emerged branches each year. In 1988 the 3rd flush was measured, and in 1989 and 1990 the 1st flush of each year was measured. Elevated ozone concentrations generally reduced photosynthetic rates, especially during the summer months, but there was no evidence of either a threshold dose or a simple linear relationship between photosynthesis and ozone exposure. There was a seasonal drop in photosynthetic rates from March to September each year. An ontogenetic decrease in photosynthesis was also evident as trees matured. Stomatal conductance also decreased as the needles aged. Seedlings irrigated with pH 3.3 solution typically exhibited the highest photosynthetic rates, presumably due to a fertilizer effect.

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Section: Treatmentsmentioning

confidence: 99%

Seasonal response of slash pine (Pinus elliottii var. elliottii Engelm.) photosynthesis to long‐term exposure to ozone and acidic precipitation*

1992

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“…Model GTC-2A) running on pure oxygen. Daily exposure from 08.00 to 20.00 h was computer controlled to follow natural diurnal fluctuations in ambient ozone concentrations (Dean & Johnson, 1991). The ozone concentration in each chamber was monitored and recorded three times an hour by ultraviolet photometric analyzers (Thermo Environmental Instruments Inc., Franklin, MA.…”

Section: Treatmentsmentioning

confidence: 99%

Long‐term effects of ozone and simulated acid rain on the foliage dynamics of slash pine (Pinus elliottii var. elliottii Engelm.)*

1992

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summary Seedlings from four half‐sib families of Pinus elliottii var. elliottii Engelm. were planted in open‐top chambers, and exposed to ozone and simulated acidic precipitation. Treatments were applied for 11 months per year for 28 months. The ozone concentrations were: charcoal filtered air (CF), nonfiltered ambient air (1×), twice the nonfiltered level (2 ×) and three times the nonfiltered level (3 ×). Ozone exposures were computer controlled to follow natural diurnal fluctuations in ambient ozone concentrations. Simulated acid rain at pH 3.3, 4.3 or 5.3 was delivered weekly at the same volume as average weekly rainfall to all chambers. Leaf area, bud number and fascicle survival were all highest in the CF chambers. Genetic differences between half‐sib families were apparent in both leaf area and the number of live buds. Leaf area and fascicle survival were reduced with every increase in ozone exposure from CF to 3 ×. Leaf litterfall increased significantly with increasing ozone exposure. Leaf growth, measured by mean leaf area and mean dry weight per needle, was not affected by ozone exposure or by acid rain. It was concluded that ozone reduced leaf area mainly by causing premature leaf senescence. The only significant effect of acidic precipitation was enhanced leaf retention in trees irrigated with pH 3.3 solution. The results indicate that the increasing levels of trophospheric ozone may significantly reduce the growth of slash pine through foliage loss. The increased leaf retention caused by acid rain is unlikely to compensate for the detrimental effect of ozone.

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Performance of a controlled-ventilation open-top chamber for climate change research

Norris

Wilkinson

Lockwood

et al. 1996

Agricultural and Forest Meteorology

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Proportional-plus-integral control of experimental ozone concentrations in a large open-top chamber

Cited by 4 publications

References 2 publications

Seasonal response of slash pine (Pinus elliottii var. elliottii Engelm.) photosynthesis to long‐term exposure to ozone and acidic precipitation*

Seasonal response of slash pine (Pinus elliottii var. elliottii Engelm.) photosynthesis to long‐term exposure to ozone and acidic precipitation*

Long‐term effects of ozone and simulated acid rain on the foliage dynamics of slash pine (Pinus elliottii var. elliottii Engelm.)*

Performance of a controlled-ventilation open-top chamber for climate change research

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