Selection of conservation areas under severe uncertainty of population dynamics in future

Background/Question/Methods Many vascular plants are threaten by various drivers such as land use change and overpopulated herbivores. More than 500 citizen botanists have archived quantitative information on population size and changing rate of population size for 1618 Japanese plant taxa twice (1994-1995 and 2003-2004). Those surveys enable us to quantify extinction risks by Monte Carlo simulations. However population size and changing rate of population size contain large uncertainty. Furthermore there is no guarantees that trend of changing rate of population size will not change in the future. We developed a robust decision-making model against those uncertainties using information-gap decision theory to derive optimal investment of conservation effort in Chiba prefecture, Japan.

Results/Conclusions Our analysis recommended that southern regions of Chiba prefecture should be more protected when we incorporated uncertainty of population size and trend of changing rate of population size. This result highlights the importance of dealing with uncertainty properly to select conservation areas effectively. We also clarified that the optimal conservation areas depend on management goals on the number of extant endangered species. Our model enables us to select conservation areas even if we do not know the degree of uncertainty of population dynamics in future.