The definition of a new plant diversity index H '(dune) for dune assessing human damage on coastal dunes - Derived from the Shannon index of entropy H '

The presented paper shows that the common usage of H' is not an appropriate index of plant diversity for studying disturbance in plant communities. H' is strongly dependent on evenness, whereas species richness and species density are not adequately incorporated. Therefore, the common usage of H' is only a measure for relative diversity in respect to the maximum possible diversity for each community. Furthermore, using the abundance of species relative to the total abundance of all species will result in the loss of information on species density (plant cover) when H' is calculated and comparisons between disturbed and undisturbed communities become difficult. Instead it could be shown that the newly introduced index H'(dune), which uses the species abundance (as coverage percentage) relative to the constant sampling area for calculation, will more clearly detect changes in species richness and composition. Sample size (plot size) is always constant and information on species density (coverage) is also incorporated in the index. H'(dune) is used to compare different coastal dunes along the southern Baltic Sea coast of Germany and Poland which differ in the degree of disturbance from recreational activities. The two main changes observed were damages because of trampling and a change in species composition, because of increasing nutrient levels. Two methods to detect different types and levels of anthropogenic disturbance and stress from recreational activities on coastal dunes are presented. (c) 2005 Elsevier Ltd. All rights reserved.