Hence, the availability of indicators and indices on a global scale is overwhelming and the diversity in their structure and applicability is enormous. Environmental and ecological impacts may cause instant effects on the biodiversity or measurable effects may be delayed, showing up in an indirect manner or even appearing at a physical distance from the place of direct impact. Indicators that are suitable for monitoring policies typically track a single area or parameter and can often - though not always - be simple in their presentation though not in their interpretation.