I read a number of Acer's eye fell on this bizarre article that explains how a tree growing under high stress may help to produce ozone in the troposphere .. carry the following ...
reading the article "The Man Who smells the forests" ("The man who sniffs the forest") published in the prestigious journal Nature (vol. 459, May 28, 2009), provides an opportunity to some thoughts on a subject that, more than once, he found space on our major newspapers with articles that often have "demonized" the trees, and to which hardly was granted a right of reply.
is well known and documented that plants emit, although very different from species to species, volatile organic compounds ( Biogenic volatile organic compounds , BVOCs) as isoprene and monoterpenes. These compounds react in the atmosphere with nitrogen oxides (NOx) to form ozone. Although not completely understood the essential functions, they could play a dynamic role in adaptive strategies to stress factors, including assumptions regarding a dominate factor in protection against parasites (eg, through the attraction of natural enemies) , thermal stress (through the stabilization of membranes) and oxidative and power deterrent to herbivores.
Although their contribution may be small compared to other sources, the emission of BVOCs from the plants could exacerbate pollution problems. It is, however, to point out that trees are well adapted and have excellent growth rates in certain areas should not be replaced because they emit only BVOCs. The amount of CO 2 and other gaseous and particulate products to manage a tree that emits a small amount of volatile organic compounds, but that is not appropriate to a given area or requiring excessive management interventions (eg irrigation, pruning, etc.), could be considerable and outweigh any possible benefit from the limited production of these compounds.
I must emphasize that the trees should not be accused of being sources of pollution, because the net benefits of their presence on air quality and reduction of anthropogenic emissions, largely offset the possible impact on the concentration of the emission of BVOC ozone.
must be emphasized that the effect of ozone on the production of green areas have been highlighted in recent times by the scientific community, so that the research had not yet possible to draw unequivocal conclusions. Some studies have quantified the effect BVOC of the formation of ozone, but no one has provided extensive findings on the influence of so-called "urban forest". As stated by Penuelas and Lluis ( Science, 3, 2003) between features of the proven and unproven BVOCs there are some scientific indications that these compounds may protect plants from high temperatures. The emission of these substances may therefore increase with global warming and other factors associated with global change , also including the change in land cover. This increase in emissions could contribute significantly (through positive and negative feedback mechanisms) to the complex processes associated to global warming, but on this there are still many issues unexplained.
Not all tree species, however, emit large amounts of BVOCs. It is therefore desirable that some attention is put into the choice of species, whereas, for example, some hardwoods such Eucalyptus (now classified as Corymbia ), Liquidambar, Robinia , Liriodendron , Populus, Quercus, Platanus (Plane), Salix and, basically, all conifers, produce high amounts do isoprenoid volatile, while as Acer and other Tilia have limited potential issuance under optimum conditions of health (Niinemets and Penuelas, 2008).
In relation to what emerges from the research conducted, it is necessary to monitor emissions from the urban vegetation, even to provide guidance for the implementation of sound environmental policy tends to reduce emissions in areas where the anthropogenic related compounds biogenic may lead to the formation of ozone. It follows, therefore, the importance of conducting research on this subject at various levels, both basic and applied to give definite answers and to prevent the general public are influenced by information false and unsubstantiated scientific or, even if it is present, is interpreted more or less surreptitiously, incorrectly. This can trigger a spiral of negative feedback in a country like ours, which already does very little for the respect of living beings from which, it is good to remember, our very existence depends.
Planting trees is one of the prerequisites for most programs to improve environmental performance of major international institutions dealing with environment and, in the present scenario of global change (not just climate), the choice of plants to be included in the green areas of Our cities can not and must not be only on the basis of design or limiting select only those native species, but must take into account the potential "contribution" environmental species to be planted will be made.
appears therefore necessary that the choice should be based on other parameters such as the amount of pollutants removed from the vegetation, the improvement in percentage of air quality, hourly and daily emissions of volatile organic compounds by the plant , and its impact on the genesis of ozone and carbon monoxide annual total amount of organic carbon, the effect of the urban forest in the area bordering on energy efficiency, the production of pollen and allergens, evapotranspiration and the resulting change in the microclimate.
The results reported in the literature, however, are not always directly applicable in Italy, for a variety of climatic conditions, is for a different social, cultural and economic and require a complete overhaul with the development of original models that take into into account the specificity of the flora and structures found in various urban area of \u200b\u200bItaly.
For this are ongoing in Italy and especially abroad, many research projects that involve multi-disciplinary research teams, addressing problems related to a comprehensive understanding of the multifunctional green now considered as a true and ecologically diverse ecosystem that ensures stable, community, sustainability of those conditions that have become indispensable in the management of green urban and suburban areas.
is my personal opinion that the work of these groups should have an echo as important as the major national newspapers and in the choice of the title or content of articles are likely to create erroneous opinion in the community and, again, misleading, with the risk to frustrate the work of researchers around the world are carrying out with difficulties due to the chronic lack of funding on this issue of fundamental importance for the quality of our lives.
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