POLLUTANTS AND FOREST HEALTH
Air pollutants may impact trees as both wet and dry deposition.
Wet deposition -rain, hail, and snow, and is largely deter...
The direct effects of O3, SO2, NO2, and NH3 include visible leaf damage, a decrease in
the number of needle age classes in...
N enrichment has been shown to increase fungal and bacterial diseases of foliage
(Snoeijers et al. 2000).
Nitrogen fertili...
O3 decreases global plant productivity (GPP) by more than 20% in 17 of the world’s
priority-conservation ecoregions (G200)...
NOx and NH3 as well as HNO3 vapor may have direct phytotoxic effects but only at high
concentrations (Bytnerowicz et al., ...
multi-effect problem extended towards radiative forcing (EEA, 2004b).
SO2 Nox NH3 VOC CO PM CH4 CO2 þ GHGs
Ecosystems
Acid...
of 7

Pollutants

environmnt
Published on: Mar 4, 2016
Published in: Environment      
Source: www.slideshare.net


Transcripts - Pollutants

  • 1. POLLUTANTS AND FOREST HEALTH
  • 2. Air pollutants may impact trees as both wet and dry deposition. Wet deposition -rain, hail, and snow, and is largely determined by atmospheric processes. Dry deposition - gases, aerosols, and dust, and is largely influenced by physical and chemical properties of the receptor surface air pollutants- sulphur compounds, nitrogen compounds, ozone and heavy metals. Sulphur dioxide (SO2) was the first air pollutant found to cause damage to trees (Stöckhardt 1871). damaging trees directly via their foliage SO2 + H20 sulphurous acid (H2SO3) and sulphuric acid(H2SO4) formation of acid precipitation indirect damage of trees
  • 3. The direct effects of O3, SO2, NO2, and NH3 include visible leaf damage, a decrease in the number of needle age classes in conifers, and elevated pollutant concentrations in plant tissues. Indirect effects include soil acidification, which results in leaching of base cations, thereby releasing toxic species of aluminium (Al). Air pollution causes water and nutrient imbalances and higher sensitivity to frost, droughts, insect pest attacks, and fungal diseases. Elevated levels of N-compounds contribute to eutrophication. N is usually the growth-limiting nutrient in forest and semi-natural terrestrial ecosystems, chronic excess of N can lead to saturation manifested by increased leaching of inorganic N (generally nitrate). Increased leaching of nitrate enhances acidification of soils and surface waters, and the risk of eutrophication of coastal marine areas and groundwater quality.
  • 4. N enrichment has been shown to increase fungal and bacterial diseases of foliage (Snoeijers et al. 2000). Nitrogen fertilisation has also been shown to increase root rot of eucalyptus caused by Phytophthora species (Marks et al. 1973). O3 can cause significant effects on photosynthesis of broadleaved species (–10%) and has less to no effect on conifers (Wittig et al. 2007) O3 gives conifers an advantage in mixed deciduous forests that can lead to changes in community composition. Fast-growing pioneer species, such as birch, aspen, and poplar, have been shown to be more O3-sensitive than climax species, such as beech and oak (Matyssek et al. in press). Plants emit isoprene into the air with high NOx concentrations,O3 levels can increase. the damaging effects of O3 are ameliorated by isoprene (Velikova and Loreto 2005, Loreto and Fares 2007). Isoprene -producing taxa may become more abundant because of their greater resistance to O3.
  • 5. O3 decreases global plant productivity (GPP) by more than 20% in 17 of the world’s priority-conservation ecoregions (G200), covering an area of 1.4 million km2 The combined effects of SO2 and heavy metal pollution and fire result in the replacement of coniferous forests by birch forests, which have a different albedo and carbon cycle An increase in the production of O3 is influenced by increased temperature, increased sunlight, decreased humidity (all components of climate change), and the increase in long-range transport of pollutants.
  • 6. NOx and NH3 as well as HNO3 vapor may have direct phytotoxic effects but only at high concentrations (Bytnerowicz et al., 1999). O3 has the highest phytotoxic potential and is predicted that by 2100 half of the World’s forest will be exposed to phytotoxic O3 levels (Fowler et al., 1999). Climate change parameters that trigger stomata opening (e.g., increasing temperature) increase the sensitivity of plants to APs like SO2 and O3. O3 slows the stomatal response to reduced water availability (Paoletti, 2005). Climate change parameters that lead to a longer growing season (e.g., warming) increase the exposure of plants to APs like SO2 and O3, whereas parameters that shorten the growing season (e.g., water stress) reduce the exposure and damage (Guardans, 2002).
  • 7. multi-effect problem extended towards radiative forcing (EEA, 2004b). SO2 Nox NH3 VOC CO PM CH4 CO2 þ GHGs Ecosystems Acidification X X X Eutrophication X X Surface ozone X X X X Radiative forcing Direct X X X Via aerosols X X X X X Via OH X X X X

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