The use of taxonomic diversity indices in the assessment of perturbed community recovery

The spatial dynamics of ecological diversity are studied in two regions (Sudbury, Canada and Harjavalta, Finland) damaged by air pollution from copper and nickel smelting. Perturbation from pollution is assumed to be most intense near the source and to decrease with distance. Monitoring sites were therefore selected to traverse these pollution gradients. Using Rhyi's generalized entropy as a measure of diversity, a monotonic pattern of increasing diversity is discovered at the recovering Canadian sites but not at the Finnish sites. Quadratic entropy and a related information-theoretical measure of taxonomic diversity, taxonomic entropy, were calculated in the hope that these diversity indices, which incorporate taxonomic distances, would provide a better understanding of these unexpected results. Quadratic entropy has the additional advantage of making use of pairwise taxonomic distances between species in a highly intuitive manner. Taxonomic has a clear information-theoretical meaning and can be calculated in the same units of measurement as Rknyi's generalized entropy thereby facilitating the comparison of classical diversity to taxonomic diversity. Quadratic entropy was found to contribute little insight as to the state of ecological recovery relative to taxonomic entropy.