Introduction

Abstract

The farmland in East Hokkaido, which encompasses two-thirds of Japan’s wetland ecosystems, has been extensively developed since the dramatic period of economic growth after World War II, and this has produced major changes in wetland and riparian ecosystems. Blakiston’s fish owl and the red-crowned crane are regarded as umbrella species in these ecosystems, and the populations of these endangered species are gradually increasing with the help of Japan’s Programs for the Rehabilitation of Natural Habitats and Maintenance of Viable Populations, based on the Act on Conservation of Endangered Species of Wild Fauna and Flora. However, it is difficult to maintain these populations at sufficient levels under the current natural conditions, because of the significant alteration in their original habitat environment. Moreover, it is expected that the human populations of most of East Hokkaido’s municipalities will decrease by about 40% by 2035, relative to 2005. As a result, dramatic changes in land use, including the abandonment of many farmlands, may occur in the next few decades.