2015 Volume 97 Issue 1 Pages 10-18
We compared the density and survival rate of current year seedlings of Cryptomeria japonica between 2 types of substrates (stumps and ground surface) in a natural C. japonica forest in Akita Prefecture to clarify the process of establishment of seedlings. Seedlings emerged biyearly during the study period. The survival rate of seedlings was higher on stumps than on the ground. The survival rate of seedlings that emerged on the ground in 1994 was 0.2%, whereas that of seedlings on stumps was 21% in 1997. At 6 years after seedling emergence, all the seedlings that had established on the ground died whereas those that established on stumps survived. Because of the higher survival rate, total number of seedlings on stumps was greater than on the ground during 3 to 6 year after emergence. No significant correlation was observed between stump height and survival rate of seedlings. However, significant correlation was observed between emergence height of seedlings on stumps and their survival rate. Higher positions of stumps appeared to be associated with higher survival rate because of earlier exposure to light in the spring in our research plot which was situated in an area that experiences heavy snow fall. Thus, it should be concluded that aggregation of C. japonica on stumps was caused by higher survival rate, not by the high density of emergent seedlings.
