386 research outputs found
Changes of partitioning and increased root lengths of spruce and beech exposed to ambient pollution concentrations in southern England
No full textDeposition velocities to Sorbus aria, Acer campestre, Populus deltoides X trichocarpa 'Beaupre', Pinus nigra and X Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment
No full textTrees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle size on the deposition velocity of particles (Vg) to five urban tree species (coniferous and broadleaved) measured at two field sites, one urban and polluted and a second more rural. The larger uptake to conifers is confirmed, and for broadleaves and conifers Vg values are shown to be greater for ultra-fine particles (Dp < 1.0 ?m) than for fine and coarse particles. This is important since finer particles are more likely to be deposited deep in the alveoli of the human lung causing adverse health effects. The finer particle fraction is also shown to be transported further from the emission source; in this study a busy urban road. In further sets of data the aqueous soluble and insoluble fractions of the ultra-fines were separated, indicating that aqueous insoluble particles made up only a small proportion of the ultra-fines. Much of the ultra-fine fraction is present as aerosol. Chemical analysis of the aqueous soluble fractions of coarse, fine and ultra-fine particles showed the importance of nitrates, chloride and phosphates in all three size categories at the polluted and more rural locatio
Urban woodlands: their role in reducing the effects of particulate pollution
No full textIn recent years a substantial research effort has focused on the links between particulate air pollution and poor health. As a result the PM10 value has been set as a measure of such pollutants which can directly cause illness. Due to their large leaf areas relative to the ground on which they stand and the physical properties of their surfaces, trees can act as biological filters, removing large numbers of airborne particles and hence improving the quality of air in polluted environments. The role of vegetation and urban woodlands in reducing the effects of particulate pollution is reviewed here. The improvement of urban air quality achieved by establishing more trees in towns and cities is also illustrated
Capture of particulate pollution by trees: a comparison of species typical of semi-arid areas (Ficus nitida and Eucalyptus globulus) with European and North American species
No full textParticulate pollution is a serious concern in developed countries especially in urban and suburban areas where it has adverse effects on human health, exacerbating a wide range of respiratory and vascular illnesses. Data are now available which indicate that similar problems probably occur in countries in transition and may indeed be worse where national air quality standards have been neither set nor monitored. Recently a variety of approaches using both wind tunnel and field measurements have suggested that trees can significantly reduce such adverse effects through their ability to capture pollutant particles. It is clear that species choice, planting design and location relative to pollution source are critical in determining the effectiveness of particle capture by trees. Here we present relative deposition velocities and capture efficiencies of five species used widely in woodland of urban and periurban areas of Europe (Quercus petraea (oak), Alnus glutinosa (alder), Fraxinus excelsior (ash), Acer pseudo-platanus (sycamore) and Pseudotsuga menziesii (Douglas fir)), and for two species being used increasingly in semi-arid regions, (Ficus nitida (weeping fig) and Eucalyptus. globulus (Eucalyptus)). These data are for species not previously worked on and measurements were made at three windspeeds. Deposition velocities and capture efficiencies are compared with those published for other tree species, with the values of deposition velocity ranging from 0.1 to 0.3 cm s-1 at a windspeed of 3 m s-1 to maximum values 2.9 cm s-1 at 9 m s-1 windspeed. Species with more complex stem structure and smaller leaves had greater relative deposition velocities. The use of such data in models to guide species choice and planting design in order to maximise particle removal from urban air are considered
Direct effects of elevated carbon dioxide on forest tree productivity
No full textThis paper provides an introduction to the book on forests and climatic change. A brief overview is given on the different sections included as well as the concepts covered in each: climate change, forestry and the science-policy interface; forestry options for contributing to climate change mitigation; adaptation regarding the impacts of climate change on forests; and policies within national and international frameworks <br/
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