FIRE AND VEGETATION HISTORY SINCE THE LAST GLACIAL MAXIMUM IN TANBA MOUNTAINS, CENTRAL JAPAN

Pollen and charcoal records from several sites in central Japan provide fire and vegetation histories since the Last Glacial Maximum. Around Lake Biwa, forest fires occurred frequently in the early Holocene indicated by an abundance of charcoal fragments (Inoue et al., 2001). Also, in the late-Holocene, fire frequencies increased everywhere with changes in forest composition and occurrences of cultivated plants such as buckwheat and cereals (Takahara et al., unpublished). By the detailed pollen, plant macrofossil and charcoal analyses and radiocarbon dates of a core, we have clarified the relationship between vegetation change and fire during the Holocene around a small pond, Jaga-ike pond (ca. 50 m in diameter) in Tanba mountains, Kyoto Prefecture. The Jaga-ike pond is located at 600-m elevation on the boundary between warm-temperate and cool-temperate zones. The modern vegetation in the site is a secondary forest dominated by chestnut, deciduous oaks and hornbeams with red pine. During the LGM, boreal forests composed mainly of Abies, Tsuga, Picea and Pinus (Haploxylon) developed and no fire events occurred. In the late-glacial, Fagus crenata and Quercus (deciduous) forests replaced them. In the early Holocene, Castanea increased abruptly following fire disturbances indicated by an abundance of charcoal fragments. During the mid-Holocene, cool-temperate forests dominated by Fagus with temperate conifers such as Cryptomeria japonica and Cupressaceae trees developed and no conspicuous fire events were detected. In the late-Holocene, charcoal data suggest that at least two major fire events were evident after ca. 2500 yr BP. These fires, which are probably caused by human activities, changed forest composition. The vegetation at ca. 2500 yr BP consisted of cool-temperate mixed forests with Cryptomeria japonica. After the first fire, Fagus crenata and F. japonica decreased considerably and Pinus increased. After the next conspicuous fire at ca.1000 yr BP, the vegetation shifted to Quercus (deciduous) and Pinus dominated forests, which similar to the modern vegetation in the area.