Modification of Shannon-Wiener Diversity Index towards Quantitative Estimation of Environmental Wellness and Biodiversity Levels under a Non-comparative Scenario

摘要

Shannon-Wiener diversity index has been used extensively in environmental studies to estimate the species richness and abundance of ecosystems. The use of the index works very well under comparative situations; where one is comparing two or more environments simultaneously. However, in non-comparative situations the index interpretation becomes very limited in terms of the information it gives on the levels of an environment’s species richness and abundance. Moreover, the magnitude of the Shannon diversity index denoted as ( H? ) is usually affected not only by the distribution of the data but also by the number of categories of species in an ecosystem. Thus, the recent increase of interest in quantifying diversity in different communities has increased the desire to develop comprehensive and highly discriminative approaches of analysis. Therefore, to add value to the index and eliminate selected weaknesses; the study sought to determine the effect of logarithmic indexing and variable integration on Shannon-Wiener diversity index model in discriminating all ecosystems involved in evaluation. Then determine quantitatively the environmental wellness and biodiversity levels of selected ecosystems. Therefore, the study utilized an eight step algorithm which was referred to as the ‘ Omatec Algorithm for Environmental Wellness Evaluation’ that introduced new variables like; individual species number logarithmic index (ISNLI), mean individual species number logarithmic index (mISNLI) and integrated logarithmic index of an ecosystem (IIE). Using simulated cases of environments to test the algorithms outputs of their wellness; a negative control environment (biodiversity poor) with one species had an environmental wellness and biodiversity levels of 0%. A positive control environment (biodiversity rich) with millions of species had an environmental wellness and biodiversity levels of 76.89%. Two ecosystems with equal diversity index of 1.6094 and evenness of 1 with 5 categories of species each had a distinguishable environmental wellness and biodiversity levels of 25.22% and 16.92% respectively. Another, two ecosystems with the same diversity index of 0.5875 and evenness value of 0.4238 had distinguishable environmental wellness and biodiversity levels of 12.30% and 8.77% respectively. In conclusion the modification of Shannon-Wiener diversity index model discriminated the biodiversity levels of environments with same number of species categories despite having same richness and evenness values. Further, the environmental wellness percentages enabled estimation of the environmental quality under non-comparative situations. The modification of the model seems promising towards contributing to quantitative evaluation of environments towards their management.