Monitoring the type and coverage of vegetation using remote sensing data is important for ecological management and research. In this study, we used drone multispectral imagery to produce a fine-scale vegetation map of secondary vegetation within part of the campus of Hiroshima University, Japan. We examined the spatial accuracy of the vegetation map through comparison with ground-based survey data in which the vegetation was classified into six physiognomic units: secondary grassland, bamboo, and woodland dominated by broadleaved deciduous, broadleaved evergreen, pine, and coniferous trees. The drone images were acquired in June, September, October, and November 2020. We analyzed the improvement in vegetation classification accuracy achieved using a composite seasonal image instead of the single season images. We also analyzed the improvement regarding the spatial accuracy of vegetation mapping obtained using various vegetation indices instead of the raw multispectral images. The overall accuracy of the seasonal composite data was 90 %, i.e., significantly higher than that of the single season images (70 %; two-way ANOVA, p < 0.01). In contrast, none of the vegetation indices produced significant improvement in terms of spatial accuracy for any of the vegetation units (one-way ANOVA, p > 0.01). The findings of the present study revealed that the advantage of capturing phenological change in multiseasonal drone data is essential for accurate vegetation mapping.

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Dysphania pumilio (R. Br.) Mosyakin & Clemants (Amaranthaceae) was newly reported for Hiroshima Prefecture, southwest Japan. Although the specimens collected showed a wide range of morphology, all specimens were shown to belong to a single polymorphic species, Dysphania pumilio, based on DNA data. A detailed description and illustration, dispersal mechanisms and potential risk to the local flora are provided.

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Allelopathic activity of Chinese tallow, Triadica sebifera (L.) Small (Euphorbiaceae) was examined by the sandwich method. As the results of the assay of T. sebifera leaf powder against lettuce seed germination, the elongation of radicle and hypocotyl were reduced by 22.8 % and 53.9 % respectively, compared to the control experiments. Comparison with the assay of Glechoma hederacea L. subsp. grandis (A.Gray) H.Hara (Lamiaceae), which is known to have allelopathic activity, suggested that T. sebifera has relatively high allelopathic activity. Unidentified allelochemicals released by T. sebifera may allow the species to behave as an invasive alien species around the world.

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A lichenized fungus, Platygramme pseudomontagnei (M.Nakan.) M.Nakan. & Kashiw. is newly reported from Mt. Senbon, located in the eastern part of Kochi Prefecture. This is a new addition of the rare and threatened species to the lichen flora of the prefecture.

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Based on nuclear Esterase DNA phylogeny, this study suggested that Depaira conilii, D. kiusiana and D. minamitanii are of hybrid origin in the D. japonica complex. The parental or ancestral species of them were not resolved completely, however, at least diploid D. pyconosora complex can be one progenitor of D. conilii.

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In recent years, the flowering of a bamboo, Phyllostachys nigra var. henonis has begun for the first time in about 120 years throughout Japan. Since 2020, we also noticed that the flowering of some bamboo groves of the species in Saijo Basin, where the campus of Hiroshima University is located. Through the virtual exploration using Google Street View and on-site surveys, we identified the eight of bamboo groves that bloomed from the year 2020 to 2021. Flowering started in spring or autumn, and most of the flowering stands died within a few months. To date, no regeneration of plants has been observed through seedlings. In this study, in addition to observing the morphology of flowers, precise longitude and latitude of the locations of the flowering bamboo groves were recorded for future follow-up studies.

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