The purpose of this paper is to demonstrate the circumstances of a life dependent on Castanea crenata forests, based on a folklore examination carried out at Oguni town, Yamagata prefecture. In this area, C. crenata forests existed around the villages, and people used the C. crenata resources until around 1945–1954. Demonstrating the way of lives in which C. crenata recourses were extremely important adds a fresh knowledge to the studies of folklore that so far have take up C. crenata far less than Aesculus turbinata. Thus, we selected three montane villages in the northern part of Oguni town as the object areas of this study. The examination clarifed ranges of C. crenata forests around the villages and showed that these forests were divided into “private forests”and“shared forests” that were used for “nuts collection”and“extraction of building materials”, respecively. Moreover, C. crenata forests were tended by the villagers, according to the growth of forest trees. The artificial culutre allowed the maintenance of the forests and the continued of their resources beyond generations.
The size change from wet fruits to carbonized cotyledons was investigated to compare the size of fossil fruits of Castanea crenata in different conditions from various Jomon sites. Both in height and width the size change from wet fruits to carbonized cotyledons had a linear regression. To critically compare fossil fruit size, a volume index for Castanea crenata fruits was calculated as the square root of height multiplied by width, because the cubic root of weight and the volume index showed a linear regression. The volume index of Castanea crenata fruits slightly increased during the early to late Jomon periods with narrow variation within populations, but varied greatly both between and within populaiton in the final Jomon period.
Dispersal efficiency of Castanea pollen was revealed by surface and airborne pollen spectra in and around a C. crenata forest, and reconstructed distribution of the C. crenata forest in the Jomon period was discussed. In the surface pollen assemblages, C. crenata accounted for more than 60% of tree pollen in inner areas more than 25 m from the edge of the C. crenata forest, >30% in outer areas of the forest, but, outside the forest, 5% at 20 m from the edge of the tree crown, <1% at 200 m, and 2.5–5% in forests with sparse C. crenata trees. In the C. crenata forest, a small quantity of C. crenata pollen was dispersed by wind, but most accumulated on the forest floor by gravity and rain. The surface and airborne pollen spectra showed that C. crenata pollen is extremely difficult to disperse. Based on the dispersal characteristics of Castanea pollen, the distribution of C. crenata forests around the Sannai-maruyama site was reconstructed by spatial investigation of fossil pollen spectra. The distribution of Castanea pollen revealed that C. crenata forests covered most of the slopes and edges of the plateau of the Sannai-maruyama site in the late phase of the early to the middle Jomon periods.
In many cases, plant remains excavated from archaeological sites have been preserved in the ethanol solution to prevent growth of fungus and decay. Comparative experiments were conducted for examining the presence or absence of effect by ethanol solution for the radiocarbon age of the plant remains. Fossil seeds from the Okinoshima site (ca. 9700 cal BP) which preserved in the ethanol solution during 3 years and dried one, and fossil reefs from the Kouzeki site (ca. 3rd Century AD) which preserved in ethanol solution during 16 years and dried one, were dated. The result of radiocarbon dates coincided in the standard deviations respectively.