The effects of digestion by Asiatic black bear Ursus thibetanus on seed germination of Japanese bird cherry Prunus grayana (Rosaceae)

抄録

To investigate the effects of digestion by the Asiatic black bear Ursus thibetanus on seed germination, we conducted germination tests in the laboratory using Japanese bird cherry Prunus grayana (Rosaceae) seeds. We collected seeds from three different bird cherry trees (subsequently referred to as 'mother trees') between August 2006 and February 2007, and treated the seeds using four different methods: digested, extracted, juiced, and intact seeds. The single-factor ANOVA method was used for statistical analysis. In our study, seeds digested by bears showed higher rates of germination (89.0±11.0SD) than extracted seeds (66.7±8.9SD), while juiced seeds showed a lower rate of germination (10.2±4.5SD) and intact seeds did not germinate at all (0%). Our research also showed that the seeds taken from the three different mother trees did not differ significantly in their germination rates. The pulp juice and endocarp hinder the germination of the seeds of P. grayana. The difference between the germination rate of seeds that had passed through the alimentary canal of a bear and those that had their pulp removed manually was not clear; however, it seems likely that germination was improved by some mechanical or chemical aspect of passing through a bear's digestive tract.