An early-Holocene pollen, mollusc and ostracod sequence from lake marl at Llangorse Lake, South Wales, UK

Abstract

An integrated analysis of molluscs, ostracods and pollen is presented from early Holocene lake marl at Llangorse Lake, Powys, South Wales. The mollusc and ostracod records reflect a littoral environment with increasing eutrophic conditions and a progressive shallowing of lake waters, although the record does not begin until around 9600 BP, probably due to the isolated location. The pollen profile provides evidence of both local and regional vegetational changes over the first two millennia of the present interglacial. Following climatic amelioration at the beginning of the Holocene, there was rapid colonization by trees and shrubs, with juniper widespread by 9800 BP, birch woodland by 9500 BP, and pine by 9300 BP. Late in the ninth millennium BP, hazel became established, to be followed during the course of the eighth millennium by elm and oak. There are indications in both the pollen and molluscan/ ostracod sequences of a relatively dry climatic regime during the early Holocene, while the pollen record suggests a short-lived climatic cooling in the middle of the tenth millennium BP.