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Reponses des vegetaux d' une region aride a une pollution atmospherique double: (SO2 + composes fluores).
1994
Ferjani B.A. | Belgacem H. | Makki B.
Long-term effects of pollutants on forest vegetation in Central Spis region
2002
Mankovska, B. (Forest Research Institute, Zvolen (Slovak Republic))
Pollution problems in forest ecosystems resulting from 100 year long operation of three smelter complexes in Central Spis are reviewed. Original data are presented with respect to temporal and spatial trends of nitrogen, sulphur and heavy metal pollution, and elemental composition of individual aerosols on leaf surface. Spruce stands in Central Spis are loaded by pollutants 1.7 times more than are critical values and the highest concentrations of As, Fe, Hg, and N were found in this region. Low Tatra National Park was the cleanest region where no element maxima were found
Afficher plus [+] Moins [-]Discussion of the effects of N with and without acidified S on a sitka spruce ecosystem after 5 years treatment
2002
Sheppard, L.J. | (CEH Edinburgh Bush Estate, Edinburgh (United Kingdom)) | Crossley, A. | Ingleby, K. | Carfrae, J. | Harvey, F. | Kennedy, V.
Significant differences in the effects of N alone compared with NS Acid have been found with respect to eutrophication and acidification. N alone had no effect on the pleurocarpous mosses, whereas NS Acid caused their death within 2 years. Both treatments enhanced stem area increment and N alone also doubled fine root growth. By contrast NS Acid treatments increased litterfall in a a dose response fashion
Afficher plus [+] Moins [-]Long-term effects of air pollution on spruce forests in the Tatra Mts. - ozone and vegetation studies
2002
Godzik, B. (Polish Academy of Sciences, Krakow (Poland). Institute of Botany) | Fleischer, P. | Grodzinska, K.
Wet-deposited - sulphur and nitrogen pollutants and ambient ozone are important anthropogenic factors affecting forest health. Regular assessment of chemistry of throughfall and precipitation water based on two-week sampling started in 1997. Passive samplers for detection of ozone concentration have been exposed on a network of monitoring stations during vegetation periods since 1998. In addition, in selected locations, UV absorption monitors for continuous O3 measurements were installed in 1999
Afficher plus [+] Moins [-]Comparison of the impacts of acid and nitrogen additions on carbon fluxes in European conifer and broadleaf forests
2018
Oulehle, Filip | Tahovská, Karolina | Chuman, Tomáš | Evans, C. D. (Chris D.) | Hruška, Jakub | Růžek, Michal | Bárta, Jiří
Increased reactive nitrogen (N) loadings to terrestrial ecosystems are believed to have positive effects on ecosystem carbon (C) sequestration. Global “hot spots” of N deposition are often associated with currently or formerly high deposition of sulphur (S); C fluxes in these regions might therefore not be responding solely to N loading, and could be undergoing transient change as S inputs change. In a four-year, two-forest stand (mature Norway spruce and European beech) replicated field experiment involving acidity manipulation (sulphuric acid addition), N addition (NH4NO3) and combined treatments, we tested the extent to which altered soil solution acidity or/and soil N availability affected the concentration of soil dissolved organic carbon (DOC), soil respiration (Rs), microbial community characteristics (respiration, biomass, fungi and bacteria abundances) and enzyme activity. We demonstrated a large and consistent suppression of soil water DOC concentration driven by chemical changes associated with increased hydrogen ion concentrations under acid treatments, independent of forest type. Soil respiration was suppressed by sulphuric acid addition in the spruce forest, accompanied by reduced microbial biomass, increased fungal:bacterial ratios and increased C to N enzyme ratios. We did not observe equivalent effects of sulphuric acid treatments on Rs in the beech forest, where microbial activity appeared to be more tightly linked to N acquisition. The only changes in C cycling following N addition were increased C to N enzyme ratios, with no impact on C fluxes (either Rs or DOC). We conclude that C accumulation previously attributed solely to N deposition could be partly attributable to their simultaneous acidification.
Afficher plus [+] Moins [-]Trends in atmospheric deposition fluxes of sulphur and nitrogen in Czech forests
2014
Hůnová, Iva | Maznová, Jana | Kurfürst, Pavel
We present the temporal trends and spatial changes of deposition of sulphur and nitrogen in Czech forests based on records from long-term monitoring. A statistically significant trend for sulphur was detected at most of the sites measuring for wet, dry, and total deposition fluxes and at many of these the trend was also present for the period after 2000. The spatial pattern of the changes in sulphur deposition flux between 1995 and 2011 shows the decrease over the entire forested area in a wide range of 18.1–0.2 g m−2 year−1 with the most pronounced improvement in formerly most impacted regions. Nitrogen still represents a considerable stress in many areas. The value of nitrogen deposition flux of 1 g m−2 year−1 is exceeded over a significant portion of the country. On an equivalent basis, the ion ratios of NO3−/SO42− and NH4+/SO42− in precipitation show significantly increasing trends in time similarly to those of pH.
Afficher plus [+] Moins [-]Interrogating trees for isotopic archives of atmospheric sulphur deposition and comparison to speleothem records
2014
Wynn, P.M. | Loader, N.J. | Fairchild, I.J.
Palaeorecords which depict changes in sulphur dynamics form an invaluable resource for recording atmospheric pollution. Tree rings constitute an archive that are ubiquitously available and can be absolutely dated, providing the potential to explore local- to regional-scale trends in sulphur availability. Rapid isotopic analysis by a novel “on-line” method using elemental analyser isotope ratio mass spectrometry (EA-IRMS) is developed, achieving sample precision of <0.4‰ using sample sizes of 40 mg wood powder. Tree cores from NE Italy show trends in pollution, evidenced through increasing concentrations of sulphur towards the youngest growth, and inverse trends in sulphur isotopes differentiating modern growth with light sulphur isotopes (+0.7‰) from pre-industrial growth (+7.5‰) influenced by bedrock composition. Comparison with speleothem records from the same location demonstrate replication, albeit offset in isotopic value due to groundwater storage. Using EA-IRMS, tree ring archives form a valuable resource for understanding local- to regional-scale sulphur pollution dynamics.
Afficher plus [+] Moins [-]The spatial distribution of different elements in and on the foliage of Norway spruce growing in Switzerland
1989
Landolt, W. | Guecheva, M. | Bucher, J.B. (Swiss Federal Institute of Forestry Research, 8903 Birmensdorf (Switzerland))
Effects of air pollutants on vegetation in the region of Sfax (Tunisia) [cultivated and wild plants]
1990
Ben Abdallah, F. (Faculte des Sciences de Sfax (Tunisia)) | Boukhris, M.
Throughfall deposition of nitrogen and sulfur in a Jeffrey pine forest in the San Gabriel Mountains, southern California
1999
Fenn, M.E. | Kiefer, J.W. (US Department of Agriculture, Forest Service, Pacific Southwest Research Station, Forest Fire Laboratory, 4955 Canyon Crest Drive, Riverside, CA 92507 (USA))