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.

Wetland biodiversity is subjected to threats from various human disturbances caused by agriculture and urbanization. We aimed to identify the changes in flora by comparing two datasets collected before and after development at Shizukari Mire, Hokkaido, Japan. We created a flora list through multiple plant surveys. Recorded vascular plant species were assigned one of four plant statuses:1) native wetland plant species, 2) native non-wetland plant species, 3) alien wetland plant species, and 4) alien non-wetland plant species. In addition, we distinguished threatened and near threatened plant species in the flora list. Our results showed an increase in the total number of vascular plant species;native wetland plant species declined, whereas that of other plant statuses (2-4) increased. The decline of native wetland plant species of Cyperaceae and Juncaceae occurred to the greatest degree in the mire part due to human disturbance. In contrast, plants of the other statuses (2-4) of Asteraceae, Poaceae, and Rosaceae were most abundant along the periphery of mire and newly appeared in the mire part after development. Moreover, many threatened and near threatened plant species, which were rare plant species, disappeared after development due to the reduction of the mire area. Our results suggest that disappeared Cyperaceae and Juncaceae species are sensitive to human disturbance and have a relatively low ecological tolerance to stress, whereas newly appeared Asteraceae and Poaceae species are tolerant to human disturbance and could possibly invade the mire area. Our results also show that wetland loss largely influences the decline of rare plant species.

Ailanthus altissima is an invasive and threatening tree worldwide. However, it is not considered as pernicious as Robinia pseudoacacia in Japan. In the field investigations of A. altissima shoot reproduction, cutting and burning increased the shoot density from 0.27 to 2.79 shoots/m². Moreover, numbers of asexual reproduction from roots and stumps were abundant in the sites of high initial stump density, whereas numbers of seedlings were small in stump-dense sites. The size of seedlings was also smaller than that of sprouts and suckers. Under conditions of a high initial shoot density, A. altissima produced an abundance of shoots from stumps and roots. Although sexual reproduction was disadvantageous for growth and competition, A. altissima germinated from seeds and expanded its distribution where initial stumps and roots were unavailable. These observations indicate that winter cutting and burning should be avoided to prevent the proliferation of A. altissima because cutting stimulates asexual reproduction, and burning facilitates the growth of seedlings and expansion of the population through the suppression of competitors.

American sea rochet, Cakile edentula （Bigelow） Hook., is a North American native plant species that has spread onto the Japanese sandy coast habitat since its first collection in 1981. This invasive species has been confirmed on almost all regions of Hokkaido Island, which is the northernmost main island of Japan. A vegetation survey was conducted on the sandy coasts of six Hokkaido regions to clarify the appearance of this alien species. C. edentula was highly dominant in the zone closest to the shoreline compared to backshore and had formed a Salsola komarovii - Cakile edentula community. Furthermore, this species was recorded in the vegetation zone on the inland side of the backshore and the front part of the first dune, which is called the Leymus dominant zone.　However, it was not found in the interior region from the top of the fore dune.　By the way, C. edentula did not appear in study quadrats on the Otsu coast （Tokachi region）, despite already invading this region.　It was considered that the reason of the absence of this species in the Otsu quadrats was the frequency of occurrence was low in this region.