| Autor: |
Werger, M. J. A., Heil, Gerrit W., Muys, Bart, Hansen, Karin, Bleeker, A., Van Deursen, W. P. A. |
| Zdroj: |
Environmental Effects of Afforestation in North-Western Europe; 2007, p109-128, 20p |
| Abstrakt: |
Eutrophication largely results from deposition of atmospheric N. The emission of N mainly originates from agriculture (NH3), traffic, power plants and industry (NOx). The most important ammonia source is emission from animal manure. The extent of this emission depends on manure composition and meteorological conditions. After N is emitted (either as NH3 or as NOx) it will be transported over short or long distances. Deposition rates vary with the structure of the earth surface, and it is often assumed that the interceptive properties of vegetation, expressed as roughness length, are constant and the same for all wind speeds and all transferable quantities. Careful evaluation of individual components of the overall transfer resistance is crucial to an understanding of how and where N will be distributed within a particular forest canopy. In the context of local scale ammonia, like encountered in the AFFOREST project, NHx will be mostly dry deposited to the forest. The Eutrend model was used for the calculation of N deposition, and it calculates concentrations and depositions as a function of surface characteristics. The model is able to describe both short and long-distance transport. The land use changes occurring in an afforestation process have different effects. The first effect is related to the removal of especially NH3 emission, while the second is related to changing deposition characteristics when turning agricultural land into forest. On top of that, after afforestation the deposition of N will change due to the effect of growing forest. Growing forest will have an effect on the roughness length, which is an important factor determining the deposition velocity. Emission from a specific location is not only deposited at that same location but is also transported and deposited in surrounding areas. Because of such transport through the air, a spatial interaction between the emission source and the deposition receptor is introduced as a complicating factor. Further investigation was needed to evaluate the relevancy of spatial interaction for the AFFOREST-sDDS. After corrections, the AFFOREST-sDSS is realistically well able to describe the deposition situation after a certain amount of years after afforestation. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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