Изменение сукцессионных систем палеофитоценозов на границе межледниковья и ледниковья позднего эоплейстоцена в пыльцевой записи оз. Эльгыгытгын (Центральная Чукотка)

Abstract

Lake El'gygytgyn is located beyond the Arctic Circle in Chukotka at 67°30' N, 172°05' E and formed following a meteorite impact that occurred 3.6 million years ago (core interval 45.79-43.65 m). In its sediments, 5 palinologic zones are distinguished; they reflect changes in paleosuccessional systems and are consistent with MIS 33, 32, and 31 (1.114-1.062 mya). During warmings, thickets of birch trees and alder were widely spread. Cliseries, caused by macroclimate changes in cold substages, are characterized by a significant reduction in tree and shrub vegetation as well as by expansion of the arctic and subarctic tundras. Grass tundras dominated and were replaced by forest tundra communities in the valleys of the Anadyr Plateau surrounding the lake. The most abrupt change of phytocenosis succession systems is observed at the border of 32 and 31 isotopic stages. The succession processes are primarily expressed in a sharp increase of birch-shrub communities in the vegetation cover and in the appearance of late succession edificators (Carpinus, Corylus, Myrica, Quercus) forming forest climax associations.