A 7500-year history of intentional fires and changing vegetation on the Soni Plateau, Central Japan, reconstructed from macroscopic charcoal and pollen records within mire sediment

Macroscopic charcoal and pollen in mire sediments from the Soni Plateau, Central Japan, were evaluated to clarify intentional fire history and relationship between vegetation transition and anthropogenic fire or climate change. The sediments deposited in recent centuries, when fire probably occurred every year, include a number density of macroscopic charcoal fragments exceeding 100 fragments/cm(3). High charcoal abundances (>100 fragments/cm(3)) were also recognized in sediments deposited at similar to 7000 cal BP and from 1500 cal BP to the present. Sediments deposited between 7000 and 1500 cal BP have a low abundance of charcoal fragments (<100 fragments/cm(3), but mainly <20 fragments/cm(3)). These results, combined with the pollen record, indicate that during the period until 1500 cal BP (except for similar to 7000 cal BP), forests of Abies, Quercus, and Fagus developed in a largely fire-free environment in and around the plateau. In this period vegetation transition was mainly influenced by climate change as follows; between 7500 and 6500 cal BP deciduous broadleaf forest grew under cool-temperate conditions; between 6500 and 5500 cal BP evergreen broadleaf forest were expanded under warming; between 5500 and 1500 cal BP evergreen broadleaf forest were developed probably under warm conditions with much precipitation. Frequent fires during a short period at similar to 7000 cal BP, probably due to human activities, possibly resulted in disturbance of forest, although Castanea forest subsequently developed across the plateau following this fire-prone period. After similar to 1500 cal BP (dated at least 1000 cal BP), periodic intentional fires resulted in the development and persistence of grassland dominated by Gramineae. (c) 2010 Elsevier Ltd and INQUA. All rights reserved.