A Pollen Analysis on the Environmental Changes during the Later Half of the Postglacial Age around the Basin of Onyang River, Asan

화분분석을 이용한 아산시 온양천 유역의 후빙기 후기 환경변화

This is a case study to research the environmental changes that occurred during the Latter Half of the postglacial age around the Basin of Onyang River in Asan, Korea. In line with this purpose, the author performed a pollen analysis and a radiocarbon dating on the deposits of alluvial fan around the upper Geumgok River, a tributary of Onyang River. Sampling point was at the altitude of about 67.5 meters, which belongs to the central zone of the cool temperate forest. The followings are the results of the study. The study area has passed through SC-I (the coniferous forest period in which Pinus was dominant), SC-II (the deciduous broad-leaved forest period in which Quercus and Castanea were dominant) and SC-III (the mixed conifer and deciduous broad-leaved forest period, in which Pinus, Quercus and Ulmus/Zelkova were dominant) respectively since about 3,000 yrB.P. SC-I period and SC-II period are presumed to be between about 3,000 and 2,000 yrB. P., and SC-III period to begin after 2,000 yrB.P. In comparison with the nationwide pollen zone during the postglacial age, SC-I and SC-II periods are contrasted with the R-IIIa zone and also the SC-III zone with the RIIIb zone. In addition, it is assumed that Pinus densiflora forest luxuriated there since 2,000 yrB.P. due to the destruction of forests, and that a lot of Fagopyrum pollen appeared; altogether, it was the so-called human interference period, from which forests began to be markedly destroyed. It is concluded that in those days inhabitants leaded agricultural life.

충남 온양천 유역의 후빙기 환경변화를 밝히기 위한 사례연구로서 온양천의 지류인 금곡천의 상류부(이하 조사지역)에 분포하는 선상지 퇴적층을 대상으로 화분분석을 실시하였다. 시료채취지점은 해발고도 약 67.5m로 현재 냉온대 중부 식생대에 속한다. 분석결과는 다음과 같다. 조사지역 일대는 약 3,000yrB.P. 이후 크게 SC-I기(期)(Pinus가 우점하는 침엽수림시대) → SC-II기(期)(Quercus·Castanea가 우점하는 낙엽활엽수림시대) → ③ SC-III기(期)(Pinus-Quercus-Ulmus/Zelkova가 우점하는 침활혼효림시대)로 변천했다. 각 시대의 연대는 SC-I기(期)와 SC-II기(期)가 약 3,000~2,000yrB.P., SC-III기(期)가 약 2,000yrB.P.~현재로 수렴된다. 전국적 후빙기 화분대와 대비하면, SC-I기(期)와 SC-II기(期)는 RIIIa 그리고 SC-III기(期)는 RIIIb에 대비된다. 그리고 약 2,000yrB.P. 이후 조사지역 일대는 삼림파괴에 따른 소나무림의 분포역이 확대되었으며, 또한 메밀화분의 출현율이 높은 점 등을 고려할 때, SC-III기(期)는 인간간섭의 시대로서 이 시대에 들어서면서부터 삼림파괴가 본격화되었고, 당시 거주민들은 농경생활을 했었을 것으로 추정된다.