خيارات البحث
النتائج 11 - 20 من 20
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.
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 [-]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 [-]Direct and indirect effects and the long term risks of air pollution on forest ecosystems: economic risks involved in forest devastation through air pollution and climate change
1993
Schulz, H. (University of Munich (Germany). Institute for Wood Research)
Wood will have a great importance as renewable raw material. Forest devastation endangers the world's future wood supply. We need a long-term strategy for forestry and forest products industries to protect complete ecological life cycle.
اظهر المزيد [+] اقل [-]General summary and synthesis | [Resume general et synthese] | [Resumen general y sintesis]
1993
Innes, J.L. | Schlaepfer, R. | Bucher, H.P. (Swiss Federal Institute for Forest Snow and Landscape Research, Birmensdorf (Switzerland)) | Kraeuchi, N. (Swiss Federal Institute for Technology, Zurich (Switzerland))
The report summarizes scientific information about forest ecosystems and their relationship to climate change and air pollution, with special emphasis on forests in Europe, North America and China. The contributions reflect the current state of science, but also uncertainties and gaps in scientific knowledge.
اظهر المزيد [+] اقل [-]Direct and indirect effects and the long term risks of air pollution on forest ecosystems: the role of forest health monitoring
1993
Innes, J.L. (Swiss Federal Institute for Forest Snow and Landscape Research, Birmensdorf (Switzerland))
Monitoring of forest health represents an important part of programmes assessing the actual and potential impact of air pollution and climate change on forests. The available information indicates that variation between years is high, indicating that long term time series will be required to identify trends in forest condition.
اظهر المزيد [+] اقل [-]