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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.
显示更多 [+] 显示较少 [-]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.
显示更多 [+] 显示较少 [-]Status and Trend of Deposition Rates in Spruce Stands of Baden-Wuerttemberg (Germany)
1993
Hildebrand, E.E. (Forest Research Institute Banden-Wuerttemberg, Freiburg (Germany))
Deposition rates in Baden-Wuerttemberg, which are monitored by sampling grid, mostly exceed critical loads. This applies especially for nitrogen input and the deposition of total acidity. In a periodic inventory of tree nutrition on a basic grid of 4 km, regions abundant and persistent Mg and K deficiency could be identified.
显示更多 [+] 显示较少 [-]Direct and Indirect effects and the Long-term Risks of Air Pollution on Forest Ecosystems in Latin America
1993
Innes, J.L. (Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf (Switzerland))
The biggest problem facing the forest of Latin America is deforestation. Air pollution also constitutes a threat to some forests, and pollution level will increase in the future. Major problem associated with photochemical smogs have been documented in the mountains around Mexico City and Santiago in Chile. Acidic deposition has been identified in some areas and is known to be affecting forest reserves in rural situations.
显示更多 [+] 显示较少 [-]Indirect effects and the Long-term Risks of Air Pollution on Tolerant Hardwood Forest Ecosystems in Central Canada
1993
Morrison, I.K. (Forestry Canada Ontario Region, Sault Ste. Marie (Canada))
There is a strong evidence to indicate that sulphates and nitrogen oxides cause increased leaching of base cations, principally calcium and magnesium from soils supporting old-growth sugar maple forest in central Canada. Sugar maple trees sequester Ca, especially in bark. A site low in exchangeable bases might become less productive, if subjected to prolonged high rates of leaching and full tree harvesting.
显示更多 [+] 显示较少 [-]Direct Effects on Boreal Forest Trees in Northern Europe
1993
Koski, V. (Finnish Forest Research Institute, Vantaa (Finland). Department of Forest Ecology)
Northern species not only tolerate but even benefit vegetatively from a slightly warmer climate than they have been adapted to. If the climatic warming remains below 5 celsius in annual mean temperature, the present forest will not be subject to direct disaster. Reproductive processes are likely to be enhanced through increased flowering and better seed maturation. There are few empirical studies on reproductive biology in new environments.
显示更多 [+] 显示较少 [-]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.
显示更多 [+] 显示较少 [-]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.
显示更多 [+] 显示较少 [-]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.
显示更多 [+] 显示较少 [-]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.
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