Habitat conditions of <i>Adonis ramosa</i> in central and southern Hokkaido.

<p>Adonis ramosa is a perennial plant belonging of Ranunculaceae and grows mainly in deciduous forests. It is distributed from central to southern Hokkaido, Honshu, and Shikoku, and is an endangered species in many prefectures. In order to effectively and efficiently conserve A. ramosa, it is one of the important issues to understand the habitat conditions of A. ramosa. Although previous studies reported the effects of light conditions on A. ramosa, no study has evaluated the local factors and the relative importance affecting the habitat conditions of A. ramosa. In this study, we evaluated the habitat condition of A. ramosa in central and southern Hokkaido, focusing on environmental factors including conditions of light, soil, litter, and surrounding vegetation. In April and May of 2021, the flowering and fruiting season of A. ramosa in central and southern Hokkaido, we set up 5 quadrats (1 m × 1 m) of each study site (7 sites in total), and counted A. ramosa abundance in a total of 35 quadrats. Also, we measured environmental factors (relative illuminance, soil hardness, litter depth, floor cover, and canopy cover). The results showed that A. ramosa abundance was positively affected by relative illuminance, and negatively affected by litter depth and floor cover. These results suggest that it is important to focus the environment with bright light, thin litter layer, and little floor vegetation in order to conserve A. ramosa. If A. ramosa habitat has to be modified due to development, it is necessary to transplant A. ramosa to such environment. In the case of monitoring and maintenance of A. ramosa habitat, mowing and raking fallen leaves are considered to be effectives.</p>