Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Photosynthesis and Transpiration Measurements as Biomarkers of Air Pollution Effects on Forests
Photosynthesis and Transpiration Measurements as Biomarkers of Air Pollution Effects on Forests
Pages 303-316
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From page 303... ...
Also, the capacity for plants to compensate for stresses by reallocating resources between organs makes it difficult to extrapolate from leaf level measurements to an assessment of whole tree and canopy processes. Any attempt for such an application would require carefully established sampling protocols to define background rates of photosynthesis and transpiration, a method for defining control measurements, and an approach for putting single leaf measurements in perspective with the whole tree.
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From page 304... ...
A few of these parameters, such as foliar gas emission, foliar enzyme activity levels, and cuticular integrity, are discussed in other chapters. Successful application of these leaf characteristics to monitor air pollution impact requires a detailed understanding of the way by which the leaf feature relates to environment (Fig.
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From page 305... ...
Photosynthesis and conductance are known to change quickly with the onset of air pollution exposures, 3. Stomatal conductance values can be used to calculate air pollution absorption by plants; 4.
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From page 306... ...
In addition, environmental factors also cause changes in carbon allocation patterns. Atmospheric stresses which limit carbon gain shift allocation to favor the shoots whereas stresses which reduce uptake of nitrogen and water by roots shift allocation to roots.
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From page 307... ...
Leaf level responses to SO2 and O3 gas exchange studies have clearly shown that mechanisms of leaf level responses can be fast and extreme. For example, a radish leaf exposed to 0.4 ppm SO2 decreased its photosynthetic rate by 75% within 10 minutes (Winner et al.
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From page 308... ...
Canopy / whole plant level Premature leaf loss Indirect effects on foliar N Figure 4. Some mechanisms of stomata!
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From page 309... ...
closure is adaptive in that air pollution absorption rates are decreased, so too is the response of leaf loss a potentially adaptive response.
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From page 310... ...
conductance and photosynthetic capacity increase with foliar nitrogen content (Field and Mooney, 1986~. If shoot growth recovery precedes root growth recovery, then foliar nitrogen content may be reduced by dilution and photosynthetic capacity and conductance will also be lowered.
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From page 311... ...
This protocol is followed to characterize the effects of leaf removal, handling, and storage on gas exchange parameters. Handling techniques that minimize artifacts include storing the leaf in cool places, retrimming the collected branch or petiole under water, and leaving the cut surface in water, and keeping the time period between leaf collection and gas exchange measurements as short as possible.
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From page 312... ...
The 14CO2 provides a tag which can be used to document photosynthesis rate and the metabolic fate of photosynthate. Air pollution effects are determined by comparing the 14CO2 fixation rates and fates for air pollution treated plants and controls.
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From page 313... ...
This study raises the possibility that o l 3c values of plants in the field may be useful in identifying plants growing with air pollution stress. However, this will require developing the capacity for partitioning °13C shifts due to air pollutants from shifts due to other environmental stresses.
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From page 314... ...
One of the challenges to those intent on using photosynthesis and conductance measurements as air pollution markers for trees will be to use these data with other carefully selected data. Using only gas exchange measurements will be insufficient for assessing trees in controlled- studies or in uncontrolled field surveys.
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From page 315... ...
1986. Joint action of O3 and SO2 in modifying plant gas exchange.
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From page 316... ...
1982. Effect of low relative humidity on o l 3C values of radish and soybean plants caused by ozone.
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