| Damage to ecosystem quality are expressed as percentage of species disappeared in a certain area, due to the environmental load (Potentially Disappeared fraction or PDF). The PDF is then multiplied by the area size and the time period to obtain the damage. The damage category Ecosystem Quality is unfortunately not as homogeneous as the definition of Human Health. It consists of Ecotoxicity, Acidification and Eutrophication, Land use and land transformation. Ecotoxicity Ecotoxicity is expressed as the percentage of all species present in the environment living under toxic stress (Potentially Affected Fraction or PAF). As this is not an observable damage, a rather crude conversion factor is used to translate toxic stress into real observable damage, i.e. convert PAF into PDF.  Damage to Ecosystem Quality is indicated by the Potentially Affected Fraction (PAF) of species. The dose-response relationship of the ambient mixture of substances follows a logistic curve. Concentrations of single substances are standardized to Hazard Unit (HU), representing the background mixture of substances. Acidification and Eutrophication Acidification and Eutrophication are treated as one single impact category. Damage to target species (vascular plants) in natural areas is modelled. Unfortunately the model was only available for the Netherlands, and it is not suitable to model phosphates. 
Example of a result obtained with the Nature Planner. The colors indicate the probability of occurrence of species. Land use and land transformation Land use and land transformation is based on empirical data of occurrence of vascular plants as a function of land use types and area size. Both local damage on occupied or transformed area and regional damage on ecosystems are taken into account.
  
Some examples of the species area relationship. Every dot is based on an actual observation. The line is the calculated correlation between the area size (horizontal) and the species number (vertical). [Taken from Köllner 1999] Back |
