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Direct and Indirect effects and the Long-term Risks of Air Pollution on Forest Ecosystems:
1993
Skelly, J.M. (Pennsylvania State University, University Park (USA))
Tropospheric ozone is the most important single air pollutant of importance to forests in eastern United States. Both broadleaf and needled trees may suffer premature foliar senescence following even low ozone exposure years. Genetic sensitivity within species is likewise prevalent.
Show more [+] Less [-]Indirect effects and the Long-term Risks of Air Pollution on Eastern North American Temperate Forest Ecosystems: Insect Outbreaks
1993
Chappelka, A.H. (Auburn University, Alabama (USA). School of Forestry)
Air pollutants cause subtle changes in natural resistance that can prediscope plants to insect attack. The majority of reports in the area of plant-pollutant-insect interactions have been correlative in nature. In the last ten years, there has emerged a growing body of literature, the vast majority with herbaceous crops, reporting on cause-effect relationships among insects and their hosts.
Show more [+] Less [-]Indirect effects and the Long-term Risks of Air Pollution on Eastern North American Forest Ecosystems: Pathological Problems
1993
Chappelka, A.H. (Auburn University, Alabama (USA). School of Forestry)
Air pollutants such as ozone may affect tree host-pathogen interactions by altering plant tissue susceptibility, plant resistance, pathogen virulence and inoculum density. Ozone has been shown to weaken trees in natural stands and increase their susceptibility to invasion by plant pathogens, such as Heterobasidion annosum. Ozone has also been shown to enhance disease development by fungi that are normally saprophytic in nature.
Show more [+] Less [-]Direct and Indirect Effects and the Long-term Risks of Air Pollution on Forest Ecosystems: A Call for Caution in Proper Diagnosis of Causes
1993
Skelly, J.M. (The Pennsylvania State University, (USA). Department of Plant Pathology)
Forest Scientists must recognize that numerous diseases and insect occurrences as well as more subtle environmental stresses are prevalent as causes of changes in forest health. Their interactions often lead to "natural" declines of individual tree species or site-species declines of multiple species. The role of air pollution should be carefully investigated in an integrative sense with these other endemic and sometimes epidemic outbreaks of biotic agents and environmental stresses.
Show more [+] Less [-]Direct and Indirect effects and the Long-term Risks of Air Pollution on Forest Ecosystems: Air Pollutants and Tree Ecophysiology
1993
Matyssek, R. (Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf (Switzerland))
The potential effects of long-term exposures to widespread low but raised concentrations above natural levels in Central Europe are still being discussed. This uncertainty results from an inadequate mechanistic understanding of the influence of air pollutants and other environmental factors of trees.
Show more [+] Less [-]Air Pollution and Forest Condition in Central Europe
1993
Kandler, O. (University of Munich, Munich (Germany).Botanical Institute of University of Munich)
Depending on their concentrations, air pollutants are dangerous to forests. With the exception of some industrial areas in the east, concentrations of air pollutants in Central Europe are below the damaging threshold as shown by the records of the monitoring stations.
Show more [+] Less [-]Direct and Indirect effects of Air Pollution on Forest Ecosystems: the Attempt of a Resume of Scientific Investigations Carried out in Nortrhine-Westphalia/FRG during the last Decade
1993
Prinz, B. (Landesansalt fuer Immissionsschutz, Essen (Germany))
Since the beginning of the 80's, a wide-spread damage to Norway spruce has occurred, mainly characterized by the light-induced decay of chlorophyll in magnesium-deficient needles. Damage also occurs in deciduous trees, especially in beech. To clarify the causes of the damage in Northrine-Wesphalian forests, extensive investigations have been carried out, which combined experimental techniques and epidemiologically orientated surveys.
Show more [+] Less [-]Direct and Indirect effects and the Long-term Risks of Air Pollution on Forest Ecosystems in the Mediterranean Region
1993
Innes, J.L. (Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf (Switzerland))
Most concern about the effects air pollution has been directed towards central and northern Europe, although considerable damage has been attributed to air pollution in the Mediterranean countries. The damage is mostly in the vicinity of point sources and can usually be related to specific pollutants such as sulphur dioxide and hydrogen fluoride.
Show more [+] Less [-]Direct and Indirect effects and the Long-term Risks of Air Pollution on Forest Ecosystems: Forest Decline and Wood Quality
1993
Bues, C.T. | Schulz, H. (University of Munich, (Germany))
The results of numerous investigations in Europe on potential relationships between forest decline caused by immissions and the wood quality of diseased trees consistently showed the technical properties of wood form diseased trees to be unaffected. Wood from diseased trees can be used without reservation.
Show more [+] Less [-]Direct Effects of Air Pollution on Physiology of Forest Trees in the Western United States
1993
Bytnerowicz, A. (USDA Forest Service, Riverside, CA (USA). Pacific Southwest Research Station)
Physiological processes of western trees are effected by ozone at concentration over 80 ppb, depending on the duration of the exposures and environmental conditions. At a single fascicle level short-term ozone exposures can cause reduction, no change or increase of stomatal conductance and net assimilation rate. Two seasons of exposures at twice level ozone concentrations caused a significant reduction of stomatal conductance and pigment concentrations in foliage.
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