Abstract
Estimation of the wood formation of the outermost annual ring allows determination of the dying or felling season of trees. A wooden stake of Zelkova serrata Thunb., used for the construction of an ancient road (before 10th century) excavated at the Ichihara-jori Site, Ichihara, Chiba Prefecture, perfectly preserved the internal structure with intact bark. The structure of the outermost annual ring of this excavated wood was compared with the wood formation of the same species in Sendai in 1995. The degree of wood formation of the excavated wood matched that of wood samples obtained on May 9 in Sendai. The phenology of Zelkova serrata at Chiba City, close to the excavation site, was estimated just two weeks ahead of that in Sendai from an observation and comparison of bud opening days in Chiba and Sendai. From these results, the felling season of the excavated wood was estimated at around April 25, when new leaves vigorously develope in spring.
