Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Decline of Red Spruce in the Northern Appalachians: Determining if Air Pollution is an Important Factor
Decline of Red Spruce in the Northern Appalachians: Determining if Air Pollution is an Important Factor
Pages 91-104
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From page 91... ...
Airborne chemicals could play a role in decline diseases by altering normal functions and enhancing natural stresses which initiate a decline, and by causing injury which competes for carbon with naturally-induced injuries, ultimately causing available carbon to drop below a level critical for maintaining vital functions. The decline of red spruce in mountain forests of the northern Appalachians appears to have been initiated by repeated winter damage to needles and buds from freezing or desiccation.
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From page 92... ...
decline when pathogens or other stresses eventually become lethal. Using Figure 1 as a guide, I have summarized the natural factors that appear to be involved in the decline of high-elevation red spruce, suggested how air pollution might fit into the disease complex and reviewed recent evidence suggesting that air pollution at ambient levels may alter red spruce to a degree sufficient to promote a decline.
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From page 93... ...
Changes in percent dead red spruce over 5 years on 56 100-m transects on Mt. Washington, NH, Mt.
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From page 94... ...
Thus, the repeated and severe episodes of injury to foliage and buds two decades ago represent a likely stress which initiated and synchronized the spruce decline and later episodes of winter injury may have served to keep the decline going. REPORTS OF WINTER DAMAGE south ME east north ME west NH VT NY QUE .
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From page 95... ...
Values are raw ring widths for each year averaged for each site, then normalized to the 131-year mean ring width. (After Johnson et al.
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From page 96... ...
and cold Decembers and Januarys (winter prior to ring formation) for the 100 years prior to 1960 when the relationship between climate and ring width changed abruptly.
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From page 97... ...
Although regionwide red spruce mortality was noted prior to severe drought, large negative residuals from the temperature-predicted ring widths during 1965-67 suggest at least a contributing and, possibly in some areas, an initiating role. Many of the insects and diseases which have affected red spruce historically are present in dead and dying trees, but their occurrence varies spatially.
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From page 98... ...
Figure ~ shows how air pollution could serve as a predisposing or contributing factor by reducing reserves available to repair injuries caused by the winter damage, drought etc. Possibly, air pollution could make trees more susceptible to the conditions that cause the winter injury to foliage and buds.
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From page 99... ...
There is evidence that air pollution might affect resistance to winter stresses. Electron microscopy studies carried out in Finland along a gradient of air pollution exposure showed greater alterations of cells and greater winter damage in areas of higher pollutant exposure (Davison et al.
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From page 100... ...
Repeated and severe winter damage to foliage and buds, and possibly drought, may act as inciting factors, and insects and pathogens appear to serve as contributing or secondary stresses. Air pollution stress might be a contributor by enhancing the effects of the conditions leading to winter injury, or by consuming energy reserves which might otherwise have been used to defend against pathogens or to repair damage from winter injury or drought.
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From page 101... ...
Chlorophyll content and dry weight of red spruce foliage from a control chamber, a chamber receiving charcoal-filtered air, and an open branch. The experimental tree was approximately 125 years old (at dbh)
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From page 102... ...
File Report A-68-S 5230. Amherst, MA: USDA-Forest Service Northeastern Area, State and Private Forestry, Amherst FPC Field Office.
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From page 103... ...
In: proc. Integrated Pest Management symposium for northern forests March 24-27, 1986.
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From page 104... ...
Laconia, NH U.S. Forest Service Northern FPC Zone.
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