خيارات البحث
النتائج 1 - 10 من 12
Effects of acidic fog on seedlings of Pinus ponderosa and Abies concolor: foliar injury, physiological and biochemical responses
1993
Takemoto, B.K. | Bytnerowicz, A. (California Air Resources Board, Research Division, Sacramento, CA 95812 (USA))
Direct damage to vegetation caused by acid rain and polluted cloud: definition of critical levels for forest trees
1993
Cape, J.N. (Institute of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian, EH26 0QB (United Kingdom))
Modelling long-term cation supply in acidified forest stands
1993
Warfvinge, P. | Falkengren-Grerup, U. | Sverdrup, H. | Andersen, B. (Department of Chemical Engineering II, Lund Institute of Technology, PO Box 124, S-221 00 Lund (Sweden))
The impact of constituent ions of acid mist on assimilation and stomatal conductance of Norway spruce prior and post mid-winter freezing
1993
Eamus, D. | Murray, M.B. (Institute of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian, Scotland (United Kingdom))
Direct Effects of Air Pollution on Forest Ecosystems of Western North America
1993
Peterson, D.L. (University of Washington, Seattle (USA))
Visible chlorotic injury and reduced foliar biomass are found in Pinus ponderosa and P. jefreyi in the mountains of southern California and the west slope of Sierra Nevada. Reduced tree growth and accelerated rates of forest succession has been documented in this area, with ozone resistant, shade tolerant species replacing P. ponderosa. There may also be some interactions among ozone, drought stress, insects and fungal pathogens.
اظهر المزيد [+] اقل [-]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.
اظهر المزيد [+] اقل [-]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.
اظهر المزيد [+] اقل [-]Effects of Acidic Deposition on Calcium Nutrition of Spruce/fir Forests in the Eastern U.S.: Implications for Physiological Processes, Growth, and Climate Interactions
1993
McLaughlin, S.B. (Oak Ridge National Laboratory, Oak Ridge, TN (USA))
Calcium avaiability to forests has been shown to be reduced by acidic deposition in several ways including: increased leaching from foliage, increased leaching from soils, and decreased availability from poorly buffered soils when aluminium is mobilized. Studies documented that acidic deposition has altered the growth and vigour of red spruce during the past three decades by changing calcium availability.
اظهر المزيد [+] اقل [-]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.
اظهر المزيد [+] اقل [-]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.
اظهر المزيد [+] اقل [-]