北海道とサハリンにおける植生と気候の変遷史: 花粉から植物の興亡と移動の歴史を探る

摘要

Vegetation and climate changes since the last glacial in the Kenbuchi Basin, central Hok­kaido and Khoe, central west Sakhalin were compared and their similarities and differences discussed. The past climates in both regions were reconstructed based on pollen assem­blages from mosses in Sakhalin and on mete­orological data in the area where the mosses were collected. During the Marine Isotope Stage (MIS) 3 in the Kenbuchi Basin, Picea forest coexisted with Abies and Larix devel­oped under a cool climate which is correlated to that in the present central Sakhalin. Vegeta­tion in Khoe during MIS 3 was also Picea forest mixed with Larix and Pinus, with Abies and Tsuga as minor components. The climate was cooler than at present. During MIS 2, the cli­mate changed enormously in both regions. A cold climate, suggested by dominant Larix and Pinus, alternated with a less cold climate indi­cated by dominant Picea and Abies. Heinrich event (H) 2, HI and Younger Dryas were recog­nized in both regions, and H3 in Khoe. Within these cold events, climate in HI was the coldest and driest in both regions. The present vegeta­tions in both regions were established at the beginning of MIS 1 by an abrupt decrease in conifers and an increase in Quercus in the Ken­buchi Basin, and by an abrupt decrease in Larix and Pinus and an increase in Picea in Khoe.%サハリンと北海道でこれまでに明らかにされた最終氷期後期以降の植生と気候について，北海道中部剣淵盆地とサハリン中西部Khoeを中心に比較検討した．気候の復元は，サハリンにおける湿原のミズゴケ中の花粉組成とミズゴケ採取地域の気象資料をもとに行った．MarineIsotopeStage（MIS）3は，両島で冷涼気候が継続した気候安定期で，エゾマツを主とした常緑針葉樹林が発達した．MIS2は，両島ともに，グイマツとハイマツの増加により示される寒冷期と，エゾマツ／アカエゾマツ，トドマツの増加によって示される気候の緩和期が繰り返された激しい気候変動期であった．両島の寒冷気候期を世界的に認められるHeinrichevents（H）およびLGMに対比した．Hlの気候は，両島ともに最も寒冷であった．MISlは初頭から現在まで，北海道ではコナラ亜属とトドマツを主とした針広混交林，サハリンではェゾマツを主とする常緑針葉樹林が発達した．