論文

© 2019 The Ecological Society of Japan. The Oriental White Stork (Ciconia boyciana) is one of the species threatened by mainly anthropogenic factor and their habitats are considered to be conserved. The first reintroduction of the species in Japan occurred in 2005. But as the species’ natural wetland habitats are declining, the birds now prefer to forage in rice paddies. Thus, restoring the paddy-dominated landscape is key for further success in the reintroduction program. In addition, a quantitative method is urgently needed to assess how much suitable habitat is available and where it is located. In this study, we identified environmental factors that affect the distribution of the Oriental White Stork and produced the first predictive spatial distribution map using 2-year satellite tracking data of reintroduced individuals. The maximum entropy (MaxEnt) approach was used to model the species’ distribution at the landscape scale (1 km × 1 km grid cells). We identified six relevant environmental variables. Our results highlight the proportion of area of rice paddies as alternative wetland habitat as the most influential variable affecting the distribution positively. Landscape diversity represented by a complex mosaic of paddies and forest is also important for the species, as total length of paddy-forest edge also had a positive effect on habitat suitability. Our predictive distribution map cannot entirely provide distribution; however, it may be valuable information when considering where should be conserved as habitat to maintain the Oriental White Stork population in Japan.

©Wildfowl & Wetlands Trust On 11 March 2011, the Great East Japan Earthquake hit eastern Japan, causing an enormous tsunami that swept through a wide area of the Pacific coast of Japan. Black Brant Branta bernicla nigricans, which forage on sea grass and marine algae in the shallow coastal waters, were one of the many bird species affected by this event. Here we overlay satellite-tracking data upon GIS landform and land-use layers to assess the consequences of the tsunami on habitat utilisation by the geese. Satellite-tracking of Black Brant following the tsunami showed that along the southern Sanriku coast in northern Honshu, where habitat had been affected by the tsunami, the geese exploited not only their traditional coastal areas but also terrestrial sites including paddy fields. Overall, 37 (4.3%) of the 868 satellite locations were confirmed to be in terrestrial habitats, possibly resulting from habitat loss in intertidal areas following the tsunami. Field observations also found geese feeding in flooded paddy fields 2 km inland of the coast. These results illustrate an adaptive behaviour by the geese to large-scale environmental changes.

In this article, we examined the value of the traditional Japanese flood control measure that uses a discontinuous levee (kasumitei). By avoiding the use of flood-prone lowlands for inhabitation and allowing floodwater movement through the kasumitei, the cost of building damage can be reduced, and water supply to wetlands can be increased. The purpose of our study was to quantify flood damage cost reductions and the potential gains for wetland species as part of an ecosystem-based disaster reduction initiative. The study was conducted in the Amano River basin in central Japan. First, we applied a drainage model and calculated the flood damage cost reduction in the floodplain from an evaluation of inundation depth differences. As part of an analysis of potential wetness, we identified areas where 1 m of flooding was predicted in rice paddies near kasumitei. We also quantified a topographic wetness index, the ratio of lowlands, and the ratio of poorly drained soil types, all of which would be beneficial to wetland species. We also investigated land-use change in the area and the relevant financial support framework. The results showed that a simulated closed levee system causes greater inundation and exposure to residents, and the value of paddy areas near kasumitei was calculated to be 43,830 JPY/1000 m2/year at the maximum. Even though the paddies tend to be poorly drained, these areas have been continuously used as paddies for the past century even under development pressure. The economic value and habitat potential of kasumitei levee systems have not been considered as part of any previous flood-management policies. We propose these existing flood control areas to be considered in the financial support framework in the context of river basin and ecosystem-based disaster risk reduction management.