湖北利川二万多年来的古植被古气候演变

CHANGES OF PALEOVEGETATION AND PALEOCLIMATE IN LICHUAN, HUBEI PROVINCE SINCE 20000B.P.

利用孢粉资料。

Six spores and pollen zones can be distinguished from the palynological assemblages since 20000B.P., reflecting six stages of paleovegetation and paleo-geography in Lichuan, Hubei Province.Stage Ⅰ .groad Leaf and conifer mixed forest, dated as 21555 B.P., indicating a warm and moist climate with many Lakes and marshes dotted, and temperature and humidity lower than those of today., because climate changed to be cold and dry Later, and pollen grains of Abies and pices increased.Stage Subalpine Abies conifer forest, 21555 B.P. - 12000B.P. .Temperature was about 4.5-9 ℃ lower than that of present day Metasequoia glyptos-trob aides preferring warm and moist weather disappeared except those in the valley.Stage Ⅲ . Conifer and broad Leaf mixed forest dominated by Pinns, Abies and Betula and considered as 12030 B .P. -9370B. P. .Climate changed warmar, and lakes and marshes were somewhat enlarged.Stage Ⅳ . Conifer forest domonated with Pinus and Mstassquoia glyptostro-boides 9370 B.P.-7260 B.P.and a temperate and moist climate.Stage Ⅴ: Evergreen broad-leavsd forest containing Metaszquoia glyptostr-oboides 7260-4130 B P.. At that time, the climate was hot and moist with the temperature about 3. 5℃ higher than that of today, enlarged lakees and marshes, and various hydrophytes.Stage Ⅵ; Metasequoia glyptotroboides mixed forest (4130B.P. -present) A great number of Metasequoia glyptostroboidcs existed, forming the pure M. glyptostroboides forest in the valley or on the depression but mixed with broad leaf trees in the mountains.The temperature and humidity were Lower than those in Stage V, and Lakes and marshes Shrank tvbecome peat.This paper also discusses the problem about succession and migration of M ,glyptostroboides .Becauze of cild weather M .glyptostroboides disappeared in this region or withdrew to the valley during 21555-12000 B.P., but grew again in 12000 B.P.and reached the maxium since 4130 B.P,