Abstract
Ligustrum lucidum, originally from China, was planted as a roadside tree and has now naturalized and spread into Japanese urban areas. L. lucidum seedlings are frequently seen in urban areas and may create colonies. Therefore, the ecological characteristics of L. lucidum, such as seed dispersal, germination, and seedling survival rates, were compared with those of native L. japonicum. In comparison with L. japonicum, L. lucidum produces many small fruit (fruit length 6.55±0.68mm, fruit diameter 5.53±0.55mm), and numerous birds were observed eating the fruit (205 individuals/22.5 hours). The results suggest that birds disperse many seeds of L. lucidum. L. lucidum germinated under shady conditions, but the seedling survival rate in a forest was significantly lower than at the forest edge. The frequency of presence increased with the amount of light. The logistic curve showed that the frequency of presence reached 50% when the relative photosynthetic photon flux density (RPPFD) exceeded 6.3%. Light also affected the size of L. lucidum saplings. This suggests that L. lucidum is a light-requiring species, for which establishment is difficult and mortality is high under shady conditions. Under bright conditions, it can establish and grow well, and will probably spread further in the future.
