末次冰期以来北海道、萨哈林岛及亚洲东北部落叶松林演变史

萨哈林岛（库叶岛）和北海道的末次冰期沉积丰富的落叶松花粉，为了搞清楚落叶松花粉百分比和实际森林密度的关系，我们系统地分析了从苔原，森林苔原以及泰加林的表土样品，根据孢粉资料恢复了两个岛屿3万年以来的植被和气候，两个岛上3万年前后 以云杉与落叶松共生的森林为主，松和冷杉现在比现代相对较冷和干的气候条件下，萨哈林在末次冰盛期的草原和泰加林主要由落叶松和松组成，和现在西伯利亚东北部的泰加林相似，在北海道末次冰盛期的草原和泰加林主要由落叶松，松以及云杉组成，气候更加干冷，在新仙女木期森林苔原分布到中萨哈林岛，而北海道的草原和泰加林以落叶松为主，气候可能比末次冰盛期还要冷，在1万年前两个岛的落叶松含量都开始下降，6000年前在北海道消失，萨哈林岛的落叶松则残存至今。

HISTORY OF LARIX FOREST IN HOKKAIDO AND SAKHALIN, NORTHEAST ASIA SINCE THE LAST GLACIAL

Larix pollen is abundant in the Last Glacial sediments of Sakhalin and Hokkaido islands. To clarify the relation between the pollen percentage of Larix and its stand density, surface samples from tundra, forest tundra and taiga in the Far East Russia were analyzed. On the basis of surface pollen data, vegetation and climate since 30 ka in both islands were reconstructed. Around 30 ka, taiga of dominant Picea coexisted with Larix, Pinus and Abies was distributed in both islands under relatively colder and drier climate than at present. During the LGM, bog and taiga were mainly composed of Larix and Pinus in Sakhalin, which could be correlated to the present northeast Siberian taiga. In Hokkaido, grassland and taiga were mainly consisted of Larix, Pinus and Picea. Climate was colder and drier than that around 30 ka. During Younger Dryas, forest tundra occurred in middle Sakhalin. In Hokkaido, contemporary vegetation was grassland and taiga characterized by the predominance of Larix. Climate was colder and drier than at LGM. Larix began to decrease in both islands at 10 ka. It disappeared till 6 ka in Hokkaido, however it survived in Sakhalin until the present.