خيارات البحث
النتائج 1 - 10 من 13
Critical loads and exceedances for eutrophication and acidification in Flanders
2002
Neirynck, J. | Langouche, D. | Ridder, K. de | Wiedman, T. | Roskams, P. (Institute for Forestry and Game Management, Geraardsbergen, (Belgium))
Critical loads were estimated for over more than 1400 receptors supporting forest vegetation in northern Belgium using simple mass balance method. Necessary data were derived from old historical soil database, recent data from forest surveys, meteo data, level I and II plots and regional studies concerning elemental sequestration in woody biomass. Deposition estimates were performed with the OPS-model, which had been validated with deposition measurements of N and S in 6 level II plots over the period 1994-1998. In addition, an edge enhancement factor was calculated to account for enhanced deposition in plots situated in forest edges
اظهر المزيد [+] اقل [-]Critical loads of acidity and model predicted changes in forest growth in Sweden
1993
Svedrup, H. | Warfinge, P. (Lunds Tekniska Hoegskola (Sweden). Kemiska Inst.) | Rosen, K. | Melkerud, P.A.
The state of transboundary air pollution [1996 update]. Report prepared within the framework of the Convention on Long-range Transboundary Air Pollution
1996
Effects and control of long-range transboundary air pollution. Report prepared within the framework of the Convention on Long-range Transboundary Air Pollution
1994
Regeneration complexities of Pinus gerardiana in dry temperate forests of Indian Himalaya
2016
Kumar, Raj | Shamet, G. S. | Mehta, Harsh | Alam, N. M. | Kaushal, Rajesh | Chaturvedi, O. P. | Sharma, Navneet | Khaki, B. A. | Gupta, Dineśa
Pinus gerardiana is considered an important species in dry temperate forests of North-Western Indian Himalaya because of its influence on ecological processes and economic dependence of local people in the region. But, large numbers of biotic and abiotic factors have affected P. gerardiana in these forests; hence, there is a crucial need to understand the regeneration dynamics of this tree species. The present investigation was conducted in P. gerardiana forests to understand vegetation pattern and regeneration processes on different sites in the region. Statistical analysis was performed to know variability in growing stock and regeneration on sample plots, while correlation coefficients and regression models were developed to find the relationship between regeneration and site factors. The vegetation study showed dominance of P. gerardiana, which is followed by Cedrus deodara, Pinus wallichiana and Quercus ilex in the region. The growing stock of P. gerardiana showed steep increasing and then steadily declining trend from lower to higher diameter class. The distribution of seedling, sapling, pole and trees was not uniform at different sites and less number of plots in each site were observed to have effective conditions for continuous regeneration, but mostly showed extremely limited regeneration. Regeneration success ranging from 8.44 to 15.93 % was recorded in different sites of the region, which suggests that in different sites regeneration success is influenced by collection of cone for extracting seed, grazing/browsing and physico-chemical properties of soil. Regeneration success showed significant correlation and relationship with most of abiotic and biotic factors. The regeneration success is lower than the requirement of sustainable forest, but varies widely among sites in dry temperate forests of Himalaya. More forest surveys are required to understand the conditions necessary for greater success of P. gerardiana in the region.
اظهر المزيد [+] اقل [-]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.
اظهر المزيد [+] اقل [-][Effects and control of long-range transboundary air pollution. Report prepared within the framework of the Convention on Long-range Transboundary Air Pollution]
1994
The Swiss National Forest Inventory, an information for the assessment of the condition and long-term changes of Swiss forest
1993
Brassel, P. (Swiss Federal Institute for Forest Snow and Landscape Research, Birmensdorf (Switzerland))
The national forest inventory of Switzerland is a large-scale assessment of the condition and changes in Swiss forests. Some of the most important advantages of the NFI are its permanence, the long-term and flexible inventory design, the high data-quality and the compatibility with the damage inventory.
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 [-]