Palynological Studies on the Peat of an Ancient Castle Site at Tagajo, Miyagi Prefecture

Abstract

A pollen analysis was made on peat material collected from an archeological castle site at Tagajo, Miyagi Pre fecture to elucidate an impact of early historic man on natural vegetation. The sediments subjected to analysis in the Pollen Zone III yield abundant Quercus pollen indicating a temperate forest developed under a warmer climatic condition than that of the present time. Zone II is characterized by a dominance of Fagus pollen and low frequencies of nonarboreal pollen. Increase of Fagus in this zone may be due to climatic deterioration. The age of the boundary between the Pollen Zone III and Zone II was known to be 2500 year B.P. and that between II and I was 1300 year B.P. The Zone I corresponds to the stage of an intensified agricultural activity marked by a sudden decline of the APF values, decrease of such tree pollen as Fagus, Quercus, Alnus, Castanea, Juglans, and increase of NAP i, e, Gramineae, Cyperaceae, Artemisia, Persicaria, Osmunda, Polypodiaceae. It is postulated that intense activities of early historic man had a great impact on the natural vegetation. Alnus and Juglans were burned away to make farmland. Quercus, Fagus and Castanea were cut down for building the ancient castle. After this catastrophic forest destruction, a migration of Pinus into the lowland of the area was detecteble in the upper Part of the Pollen Zone I.