Quantifying the Components of Biocomplexity Along Ecological Perturbation Gradients

The study of ecological perturbation gradients provides a unique opportunity to investigate the utility of various biocomplexity indices. The ability of four measures of biocomplexity (quadratic entropy, taxonomic entropy, total complexity and total diversity) and their components to quantify the nature and degree of perturbation in plant communities was assessed by how closely each measure reflected the trends in biocomplexity that are expected to occur along a gradient of decreasing perturbation. The measures were applied to two landscapes, located near Sudbury, Canada and Harjavalta, Finland, perturbed by nickel–copper smelter emissions. Taxonomic entropy was determined to be the most useful of the four measures as it has a clear information-theoretical meaning, the relative contributions of classical diversity and taxonomic information can be easily isolated, and its computation is straightforward relative to the other measures. Additionally, it is relatively insensitive to community evenness, thereby rendering it less sample-size dependant and a more appropriate measure to use for comparisons between studies as well as for conservation and restoration purposes.