Time-lagged responses of indicator taxa to temporal landscape changes in agricultural landscapes.

Biological indicator methods represent one of the most effective and widely used strategies for understanding the influences of environmental degradation on biodiversity in various landscapes. Researchers and land managers generally assume that the present distributions of biological indicator species are influenced by the current environment. However, recent studies have suggested the importance of past environments to species distributions (i.e., a time lag between changes in species distribution and habitat alterations). Therefore, it is necessary to understand the effects of past environments on the distributions of indicator species. We conducted a survey on the Tokachi Plain in Hokkaido, Japan. We targeted two taxa that have been widely used as indicator species (carabid beetles and bats) and investigated whether past landscape environments influenced their present distributions. We showed that past landscape environments (5 decades prior to the present) influenced the distributions of some ecological trait groups in each taxon (large body size for carabid beetles and a 25 kHz peak echolocation frequency for bats) and that these effects varied among groups. Our results suggest the need to consider the dynamics of land-use changes and the effects of past environments on the distributions of indicator taxa, otherwise we may misunderstand the effects of environmental degradation on biodiversity. [ABSTRACT FROM AUTHOR]