2006 Volume 14 Issue 1 Pages 15-27
Recent analyses of fossil woods and fruits revealed the growth of Rhus verniciflua trees in Japan since the Early Jomon Period. Distribution of this plant around archaeological sites, however, could not be clarified with these analyses, because woods and fruits may have been brought to the sites from far away by Jomon people. Previous descriptions indicated that the pollen sculpture of Rhus verniciflua was slightly different from that of other Rhus species. To clarify the basis of distinction, the pollen sculpture of six Japanese Rhus species were studied with optical microscopy and image analysis. The results revealed that, distinct from the other species, Rhus verniciflua pollen have reticulate sculpture with lumina which are regular in shape and size. Re-identification of Rhus fossil pollen at three sites of the Early Jomon Period in Aomori Prefecture showed that Rhus verniciflua appeared at ca. 5600 yr BP with the establishment of the Castanea forest around settlements and disappeared at ca. 4500 yr BP with the elimination of the Castanea forest caused by the expansion of the Aesculus forest.