Flandrian vegetational history of southeastern England. Pollen data from Pannel Bridge, East Sussex.

Pollen data, plant macrofossil remains and lithostratigraphy are used to reconstruct Flandrian vegetational history from a coastal site in south-eastern England. The record at this site, Pannel Bridge in East Sussex, extends back to c. 10000 BP and is the most complete so far obtained from this region. The thirteen pollen assemblages zones defined reflect, in part, the complex development of the site. Prior to c. 8500 BP, wetland in the Pannel valley was localized around the site. Between c. 8500 and c. 6000 BP, in response to changes in coastal configuration, such areas underwent expansion and the valley floor was occupied alternately by sedge fen and Alnus carr. A period of stability followed, with Alnus-dominated communities prevailing for c. 2000 yr. From c. 4000 to c. 2200 BP local conditions were more open with Cyperaceae and subsequently Myrica the dominant wetland types. Alnus carr became re-established c. 2200 BP. The vegetational history of adjacent dryland areas is obscured by the changing local conditions and nature of the deposits investigated. The problems of reconstructing past vegetation from coastal peats are explored. Amongst these are the determination of the pollen source area, establishing an environment of origin for many herb types, and distinguishing the processes controlling wetland vegetational change. The discussion focuses on the arrival and expansion of arboreal taxa in the early Flandrian and human activity. Unusually, Alnus is present in the pollen and macrofossil record from c. 10000 BP onwards. In dryland areas, after an initial Pinus, Betula phase, Corylus populations expanded c. 9500 BP, Quercus and Ulmus became woodland components from c. 9100 BP and c. 8400 BP onwards respectively. Pollen values for Tilia increased c. 7000 BP and Fraxinus c. 5900 BP though both of these taxa were probably locally present earlier. Openings in the forest canopy appear to have persisted after the arrival of the deciduous trees, possibly as a consequence of human activity during the mesolithic. There is some palynological evidence for human presence accompanying the elm decline, though substantial clearance did not occur until the decline in Tilia, c. 3700 BP. This, and a subsequent phase of disturbance c. 3200 BP, appear not to have been followed by periods of intense human activity. Woodland regeneration may have occurred c. 2000 BP.