Pollen stratigraphy, vegetation and environment of the last glacial and Holocene - A record from Toushe Basin, central Taiwan

The pollen record from the Toushe Basin (23 degrees 49'N; 120 degrees 53'E; 650 m above sea level), a peat bog of central Taiwan, displays a continuous vegetation history of the past 96,000 yr BP of monsoon Asia. Instead of today's closed subtropical evergreen broadleaved forest dominated by Machilus-Castanopsis surrounding the basin, temperate deciduous forest predominated during most of the last glacial. In early MIS 4, Alnus reaches the highest value of the whole sequence (60-70%) representing temperate deciduous forest and relatively cold and arid conditions. Following this stadial, Alnus and herbs (mainly Cyperaceae) dominated alternately, with a minor increase of Castanopsis. Peaks of monolete spores between cal. 42.2 and 37.0 kyr BP (kyr BP represent calibrated years) indicate episodic wet conditions. The later glacial, especially between 23.2 and 18.7 kyr BP. shows a high percentage of Gramineae, indicating dry and possibly sometimes cold conditions. The late glacial shows a remarkable increase of warm-temperate to temperate forest elements, such as Ilex, Cyclobalanopsis and Symplocos. At about 15.1 kyr BP a peak of monolete spores indicates wet-warm conditions. A subsequent sharp increase of Salix and then Gramineae between 13.0 and 11.6 kyr BP corresponds to the Younger Dryas. A warming event at 11.5 kyr BP is also evident. The Holocene is characterized by warm-wet conditions of the overwhelmingly abundant monolete spores since 10.7 kyr BP and the prominent increase of Castanopsis. (c) 2005 Elsevier Ltd and INQUA. All rights reserved.