In this study, the habitat of bumblebees, which is indispensable for pollination and maintenance of fruiting success of Cypripedium japonicum Thunb., is estimated from the landscape structure around the habitat and the flowering status of flower-visiting plants, and the relationship with the fruiting success of Cypripedium japonicum is examined. The purpose is to help conserve the land. Five research sites, Sakura-A, Sakura-B, Yotsukaido-A, Yotsukaido-B and Ichihara-A, supporting orchid communities were established in northwestern Chiba Prefecture. The number of individual plants, as well as the flowering and fruiting success rates, were observed for each community. The characteristics of the surrounding landscape were identified, and the relationship with the fruiting success rate was analyzed for each community. Based on the foraging behavior of the bumble bees, a 1 km radius target area was established around each of the five sites. The QGIS application was utilized to calculate the total area accounted for by each of the eight landscape categories for each of the five research sites. Extant research was used to identify the pollen sources preferred by the two species of bumble bee prevalent in the study region, Bombus ardens ardens Smith and Bombus diversus diversus Smith; and route censuses, were employed to quantify the presence and flowering status of these plants for each of the three sites(Sakura-A, Yotsukaido-A, -B). The fruiting success rates were higher in areas with larger areas of broad-leaved forests. One possible explanation for this is that abandoned animal burrows suitable for bumble bee nesting sites are more prevalent in the broad-leaved forest. Another explanation may be that more pollen sources are available in this habitat. The fruiting success rate was low for areas with smaller percentages of forest cover. Higher concentrations of coniferous tree plantations were also associated with lower fruiting success rates; and thus support very little forest floor vegetation.
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