Conservation of endangered species in Japan’s agroecosystems: focusing on specified class II nationally rare species of wild fauna/flora

Specified class II nationally rare species of wild fauna/flora designations were first made in Japan for three species, the Tokyo salamander (Hynobius tokyoensis), golden venus chub (Hemigrammocypris rasborella), and giant water bug (Kirkaldyia deyrolli). These species depend on the shallow water in agroecosystems, secondary forests, and parks. The objective of this paper was to provide an overview of the factors relating to their conservation, which were as follows: (1) the landscape affects significantly on distributions of three species. H. tokyoensis and K. deyrolli both require landscapes in which wetlands and forests connect. While H. rasborella inhabits isolated ponds also, the original habitat is a flood plain where fishes seasonally move temporary pools for spawning. Therefore, channel networks are needed to protect fishes including H. rasborella. (2) Agricultural land infrastructure affects the three species, as dry paddy fields and concrete-lined ditches are unsuitable for them, as well as other aquatic animals. Several construction methods, however, have been trialed to allow fish to live in modernized ditches. (3) K. deyrolli is highly sensitive to pesticides. (4) Mid-summer drainage of paddy fields will threaten populations of H. tokyoensis and K. deyrolli as these paddy fields lose water before these species have completed their metamorphosis. Wet-paddy fields that are not completely dried, postponement of mid-summer drainage, and the installation of diversion ditches, however, could all help to mitigate this issue. (5) The impacts of abandoned cultivation and pond management are significant for these species. (6) Invasive alien species have a significant impact on H. tokyoensis and H. rasborella. (7) Habitat creation and translocation of these species has often been successful. However, the sustainability of the translocated populations is a challenge. When these species are introduced outside their natural habitats, it is thus necessary to consider the ecosystem of the destination area and the genetic background of the target species. I conclude that the combination of biotopes with wildlife-friendly farming and continuity of paddy fields with forests throughout the landscape secure the population sustainability.