Abstract:

Baiyangdian is a large lake in the North China Plain. Pollen analysis of Bai No.4 Drill and field investigation revealed that Baiyangdian Lake was formed during the Middle Holocene and began to shrink and fall into pieces with the cooling and drying process of the climate since the Late Holocene, but it was reserved and developed by human activities.There are five pollen zones in the profile of the Bai No.4 Drill core. On this basis the Holocene strata of the Baiyangdian Lake district can be divided into four stages by means of 14C dating.

Stage 1. Old Holocene (ll000—9000a.BP.), The vegetation was needleleaved and deciduous broad-leaved mixed woodland dominated by Pinus and steppes. The climate was temperate and subhumid.

Stage 2. Early Holocene (9000—7500 a. BP.),Pinus woodland and steppes with a semi-cold and semi-arid climate.

Stage 3. Middle Holocene (7500—3000 a. BP. ), Pinus-Quercus-Betula woodland to swamp. There were allot of Ceratopteris in the swamp at that time. So we think that the temperature was 2–4℃ higher and the precipitation 200 mm more than that at present.

Stage 4. Late Holocene (3000 a. BP. to present), Pinus with deciduous broad-leaved woodland scattered among herbs to artificial lake. The climate was cool and semi-arid. The development of Baiyangdian Lake has been dominated by both natural climate change and human activities.