房総丘陵における植生変遷に関する花粉分析学的研究

• Main Authors: 内山, 隆, ウチヤマ, タカシ, Uchiyama, Takashi, 江上, 邦博, エガミ, クニヒロ, Egami, Kunihiro, 齋藤, 崇人, サイトウ, タカヒト, Saito, Takahito
• Language: Japanese
• Published: 2015
• Subjects: Holocene; Vegetation change; Pollen analysis; Boso hill; Subarctic
• Online Access: https://lib.cku.repo.nii.ac.jp/record/964/files/KJ00009791443.pdf

In comparison with other areas, the forest vegetation of the South Chiba Boso Hill is sequentially compressed vertically, and the flora of the Boso area is characterized by a mixture of species derived from a warm temperate zone and a cool temperate zone. In order to examine the historic background of the characteristic vegetation, dating, pollen analysis, and tephra analysis were performed using sediment from the Holocene epoch. In particular, classification focused on Castanopsis - Castanea pollen under SEM and a close inspection of Tsuga pollen under LM. As a result, three phases of change in the forest were determined from ca. 9,000 cal BP to ca. 6,000 cal BP. The first phase was dominated by Pinaceae coniferous and a broad-leaved mixed forest mainly involving the Ulmus, Zelkova and was maintained to ca. 8,500 cal BP. In the second phase, subarctic coniferous trees including Picea and the Tsuga diversifolia were distributed to ca. 7,000 cal BP. In the third phase, there was a decrease in Tsuga dive sifolia, and an increace in temperate T. sieboldii after ca. 6,300 cal BP. At the same time, a Castanopsis forest mainly involving C. cuspidata developed. After that, over ca. 6,000 cal BP, Castanea and evergreen oak increased, and Cryptomeria, a middle temperate forest including T. sieboldii, was established. On the other hand, the local herbaceous vegetation which adapted to the back marsh of the Obitsu River was established intermittently. It was speculated that the geographical conditions of dense valleys among low elevation hills and the accompanying low temperature environment in this area, led to favorable conditions for the growth of a coniferous forest, and led to a stagnation of the distribution expansion of deciduous and evergreen broad-leaved forests and formed the characteristic vegetation compression. KJ00009791443 departmental bulletin paper