2016 Volume 33 Issue 2 Pages 53-64
To understand the conservation of the endangered butterfly Tongeia fischeri (Eversmann), we assessed eggs distributed on its host plant, Orostachys japonicus, as well as the growth conditions of O. japonicus. We also aimed to clarify the vegetative environment of T. fischeri and to discuss potential conservation strategies, which vegetative environment means habitat for the butterfly and for the host plant. We conducted investigations at four riverside study sites in Matsumoto and Azumino Cities, Nagano Prefecture, central Japan. The Tazawa study site contained no T. fischeri eggs or adults, but did contain O. japonicus, T. fischeri’s host plant. We found no serious differences in plant species composition among sites. However, the distribution area of O. japonicus was smaller (23.3 × 3 m) and O. japonicus was less dense (0.26 /m2) at Tazawa than at the other sites. To ensure T. fischeri’s survival, the distribution area and/or density of O. japonicus should be maintained above levels. Overtopping by shrub and tree species during plant community succession, which results from upstream dams’ reducing the frequency of flood disturbances, may hamper O. japonicus growth. Thus, artificial vegetation controls such as mowing are necessary to conserving the riverside habitats of T. fischeri and its host plant, O. japonicus.
