خيارات البحث
النتائج 21 - 30 من 35
Climate Change - Potential Impacts on Subalpine Forest Ecosystem
1993
Kraeuchi, N. (Swiss Federal Institute of Technology, Zurich (Switzerland))
The ranges of the ecosystems move when the climatic pattern changes. Simulations have shown that a global warming would cause important changes of the species composition in subalpine forests. Deciduous trees would invade today's subalpine belt. Various conifers would be displaced and migrate into alpine zone. The model simulations are based on the IPCC climate scenarios.
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 [-]Direct and Indirect Effects and the Long-term Risks of Climate Change on Forests: Tropical Deforestation and Carbon Dioxide
1993
Jarvis, P.G. (University of Edinburgh, Scotland (United Kingdom). Institute of Ecology and Resource Management)
Destruction of forests leads to the release of carbon dioxide stored in the wood and also usually results in major releases of carbon dioxide stored in soil. Annual releases of carbon dioxide from destruction of tropical forests was estimated at about 1650 million tonnes per year.
اظهر المزيد [+] اقل [-]Direct and Indirect Effects and the Long-term Risks of Air Pollution on Forest Ecosystems: Effects on Soil Nutrition
1993
Guang-Jing Ma | Bai-Zhong Li | Ping Zhang | Jing-shen Liang (Chinese Academy of Forestry, Wan Shou Shan (China). Research Center for Forest Environment)
Atmospheric pollutant can cause direct effects mediated by foliage and indirect effects mediated through soil. Biotic and abiotic factors can confound relationships among nutrient cycling, growth loss and mortality and air pollution. Changes in the soils could result from acidic deposition. Changes could include increased fertility as a result of sulphur and nitrogen input to soils that are deficient in these elements or decreased fertility through ion leaching or mobilization of toxic substances as aluminium.
اظهر المزيد [+] اقل [-]Direct and Indirect Effects and the Long-term Risks of Air Pollution on Forest Ecosystems: Effects on Soil Micro-organisms
1993
Innes, J.L. (Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf (Switzerland))
The soil biota plays a critical part in the functioning of forest ecosystems. Acidification and heavy metals have the greatest direct effects on the soil biota. However pollutants can have indirect effects through their influence on tree root systems. Acidic deposition can decrease the incidence of mycorrhizal infection, but soil pH and concentration of nitrogen and certain forms of sulphur are also important.
اظهر المزيد [+] اقل [-]Socio-economic assessment of global change and air pollution-related forestry damage
1993
de Steiguer, J.E. (USDA Forest Service, Raleigh, North Carolina (USA))
Information on potential forestry losses seems to be crucial to government officials that they can properly assess the costs and benefits of limiting pollution and greenhouse gas emissions. However very few socio-economic assessments of potential losses have been completed.
اظهر المزيد [+] اقل [-]Effects of climate change and atmospheric pollution on forest ecosystems in eastern North America
1993
Hall, J.P. (Forestry Canada, Ottawa (Canada))
Climate change will be the major impact on all forests, included increased risk of large-scale fires, enhanced susceptibility to insects and diseases. Direct effects of air pollution on vegetation include damage to protective surface structures, disturbance of photosynthesis.
اظهر المزيد [+] اقل [-]Air pollution and forests - an overview
1993
Innes, J.L. (Swiss Federal Institute for Forest Snow and Landscape Research, Birmensdorf (Switzerland))
Considerable uncertainty has surrounded the relationship between forest growth and forest declines in Europe. Although growth decreases have been recorded in several years, by the end of the 1980s, increment at many sites had reached a level higher than any previously recorded. Fertilization by carbon dioxide, favourable climatic conditions and better stand management may all have contributed.
اظهر المزيد [+] اقل [-]Pedologic and nutritional aspects of enhanced carbon-dioxide storage in forest ecosystems
1993
Huettl, R.F. (Forestry Dept. Kali and Salz AG, Kassel (Germany))
Enhanced forest growth in combination with relatively high Nitrogen deposition may result in further pedologic and nutritional changes and an even greater destabilisation of forest ecosystems.
اظهر المزيد [+] اقل [-]Direct and indirect effects and the long term risks of air pollution on forest ecosystems: effects and risks on ectomycorrhizae
1993
Brunner, I. (Swiss Federal Institute for Forest Snow and Landscape Research, Birmensdorf (Switzerland))
Two main effects on ectomycorrhizae can be distinguished: direct effects due to a change in the soil chemistry and indirect effects due to a change of the carbohydrate supply from the host trees to the roots.
اظهر المزيد [+] اقل [-]