Biodiversity Impact Assessment Based on Extinction Risks

Abstract

Ecological impact is usually evaluated by the value of ecosystem services. I introduce a method to evaluate biodiversity. The red data book of Japanese vascular plants is based on their extinction risk. During evaluation of this red data book, about 2000 taxa were evaluated using population data and rates of decline for ca.4400 grids, each of ca.100 km². This database can be used to estimate the impact of human activity on extinction risk of threatened plants. In order to evaluate extinction risks and apply the evaluation to conservation actions, the mean time of extinction and discount mean time to extinction are defined as measures of extinction risk. The present value of a species’ persistence in the future decreases exponentially. Increases of the inverse, and logarithm, of the discount mean time to extinction are also considered measures of the extinction risk. We applied these measures to an environmental impact assessment for the Japanese World Exposition that was held in 2005, Aichi Prefecture. Development will have a greater impact on threatened Salvia species than star magnolia, which has been conserved by changing the site plan.