Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Tree-Ring Analysis as an Aid to Evaluating the Effects of Air Pollution on Tree Growth
Tree-Ring Analysis as an Aid to Evaluating the Effects of Air Pollution on Tree Growth
Pages 157-168
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From page 157... ...
The plethora of regional pollutants coupled with insufficient physiological understanding species respond to pollutants makes any causal link between regional pollution and tree growth difficult to infer. A variety of statistical analysis procedures are available to search for anomalous behavior in tree rings in the form of ring-width decline anti changes not explained by climate.
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From page 158... ...
These effects, coupled with geometric increases in cambial area each year, frequently cause these ring widths to decrease with age in a curvilinear fashion. This decrease, which is an intrinsic property of tree growth, must not be misinterpretated as an indicator of pollution stress.
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From page 159... ...
To compound the probable lack of a useful normal growth model, we do not have a good expectation of what a pollution effect looks like in tree rings other than, perhaps, that ring widths should decrease in the presence of air pollution. In itself, an expectation of anomalous ring-width decline is nonunique and, therefore, insufficient for identifying a pollution effect on regional forest growth.
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From page 160... ...
(1987) were able to demonstrate conclusively the existence of a widely synchronous decline in red spruce ring widths after about 1960 in the northern Appalachians.
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From page 161... ...
An example of step-like decline in ring width in red spruce. The dashed line is a simple step-function fitted to the tree-ring series by least squares.
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From page 162... ...
Having standardized the ring widths, Cook ~ 1987a) modeled two slightly different forms of the same red spruce tree-ring chronology with monthly mean temperatures for the years 1890- 1950 using stepwise multiple regression analysis.
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From page 163... ...
to study the decline of several tree species. Their results also indicate that climate alone could not explain the level of decline seen in the ring widths, although the climatic response appears to change less than it does for red spruce in North America.
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From page 164... ...
Still missing is a useful understanding of how ambient levels of various air pollutants affect the growth of different tree species under natural forest conditions. Until this understanding is obtained, any causal link between air pollution and forest decline that is inferred from tree-ring analysis alone will be very difficult to defend.
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From page 165... ...
1981. The smoothing spline: a new approach to standardizing forest interior tree-ring width series for dendroclimatic studies.
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From page 166... ...
1988. Relationships between climate and red spruce growth and decline in the Northern Appalachians.
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From page 167... ...
1987b. Testing for stand dynamics effects on red spruce growth trends.
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From page 168... ...
1987. Detecting the effects of acidic deposition and C02-fertilization on tree growth.
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