The testing of three indicator systems for trophic state in grasslands

Three vegetation-based indicator systems for the assessment of the trophic state of soil were tested on grasslands. External parameters were gross production and nitrogen supply. A high correlation was found between indication figures of the releves and external parameters. There was some evidence that, under certain conditions, indicator systems could provide ordinal as well as cardinal information. The reliability of the indicator systems was not entirely dependent on the completeness of the vegetational information. The lack of abundance data and the ignoring of rarely occurring species did not seriously affect the strength of correlation. It was concluded that indicator systems can be useful tools in ecological research as well as in nature conservation policy.