2024-03-28T16:01:05Z
https://nagoya.repo.nii.ac.jp/oai
oai:nagoya.repo.nii.ac.jp:00018150
2023-01-16T04:06:41Z
879:1183:1184:1612
Pollen analysis of Karekare Swamp in Rarotonga, Cook Islands
クック諸島ラロトンガ島カレカレ湿地の花粉分析
藤木, 利之
83733
奥野, 充
83734
森脇, 広
83735
河合, 渓
83736
中村, 俊夫
83737
Fujiki, Toshiyuki
83738
Okuno, Mitsuru
83739
Moriwaki, Hiroshi
83740
Kawai, Kei
83741
Nakamura, Toshio
83742
pollen analysis
vegetation change
human impact
human migrations
radiocarbon age
2013-03
Rarotonga is a small island in central Polynesia having the circumference of approximately 32 km. The highest peak is 652 m above sea level and a reef flat extends several hundred meter to the reef that then slopes steeply to deep water surrounds the island. Rarotonga is densely covered with a jungle of ferns, creepers and towering trees. Karekare Swamp in Matabera, located in the northeast of the island is a back swamp. We obtained a 340-cm sediment core at the site of the swamp (21°12' 57.5"S, 159°44' 23.1"W) using a hand auger sampler. The core sediments were divided into three layers, i.e. sandy peat from 0 to 90 cm, undegraded peat from 90 to 250 cm,and dark brown peat from 250 to 340 cm in depth. This paper present results of pollen analysis and AMS radiocarbon (14C) dating on the cored sediments. Eight 14C dates obtained from charcoal and plant fragments indicate that cored sediments cover the past 6000 years. Arecaceae pollen grains are dominant in all of the sediments. While Barringtonia pollen decreases rapidly in the upper part. The appearance ratio of Pandanus pollen is high in the lower part, but it decreases rapidly in upper layers. The appearance ratio of herbaceous plants such as Poaceae and Cyperaceae is remarkable in the upper layers. Considering that Barringtonia and Pandanus grow in the hinterland, decrease in Barringtonia and Pandanus and increases in herbaceous plants suggest a disturbance of the hinterland vegetation. The appearance of Chenopodiaceae pollen of upland weeds and cucurbitaceae and Vigna pollen grains of cultivated plants suggests definite traces of humanity upper 130 cm. The appearance ratios of Pandanus pollen and monolate type fern spore show the increase in 157 to 147 cm. The radiocarbon age indicates about 3700 BP. Judging from the increase of Pandanus pollen and monolate type fern spore, this result suggests human activities. Hence human settled in Rarotonga at about 3700 BP, which is considerably older than that of settlement in eastern Polynesian obtained before.
南太平洋のクック諸島のラロトンガ島は、サンゴ礁に固まれた周囲32km、海抜652mの火山島である。ラロトンガ島北東部に位置するカレカレ湿原において400cmの堆積物を採取し花粉分析を行った。樹木花粉ではサガリバナ属、ヤシ科、タコノキ属花粉が優占し、非樹木花粉ではイネ科、カヤツリグサ科、単条溝型シダ胞子、三条溝型シダ胞子が優占する。サガリバナ属の急減とイネ科・カヤツリグサ科の急増、さらに畑作亜雑草のアカザ科や栽培植物由来と考えられるウリ科やアズキ属などの出現から、約680BPに確実な人類の痕跡が見られた。現在、ゴバンノアシ(サガリバナ属)が沿岸部に優占していることを考慮すると、ゴバンノアシ林が破壊され、その跡にイネ科やカヤツリグサ科、シダ類の草本やP. tectoriusが侵入し、草地が広がったとみられる。また約3700BPあたりでタコノキ属と単条溝シダ胞子の増加がみられる。これを人為的な植生変化と考えると、ポリネシア人がこの時期にラロトンガ島に定住した可能性がある。
名古屋大学年代測定総合研究センターシンポジウム報告
departmental bulletin paper
名古屋大学年代測定資料研究センター
2013-03
名古屋大学加速器質量分析計業績報告書
24
150
158
jpn