The trend in environmental conditions is an important indicator for making statements about the dominant pressure factors that threaten nature. There are different indication systems and this project is investigating which system is most suitable for the indicators.
The indicators for the trend in environmental conditions are derived from indication values of plants for soil pH, groundwater level (GVG) and nutrient richness/trophy degree. These indicators are used to make statements about the dominant pressure factors that threaten nature in the Netherlands; acidification, desiccation and eutrophication. In the current calculation of national and provincial indicators, PBL, WOT use a different indication system (WW numbers) than the provinces in area studies (Iteratio). Exploratory analyzes suggest that both indication systems do not always convey the same message about magnitude and changes in environmental conditions. It is still unclear what methodological differences cause the different outcome. This project examines the effect of the methodological differences on the indicators and provides recommendations on how to use the indication systems.