The late quaternary vegetation history of the Southern Welsh borderland

Stokes, Karolyn (2004) The late quaternary vegetation history of the Southern Welsh borderland. (MPhil thesis), Kingston University, .


Palaeoecological analysis and lithostratigraphic investigations are used to reconstruct the late Quaternary vegetation history of a previously little studied area, the Southern Welsh Borderland. Particular emphasis is placed on the Last Glacial-Holocene transition and the arrival of tree taxa during the early Holocene. Palynological data collected from two sites, Bridge Sollers (near Hereford) and Stansbatch (near Presteigne), are accompanied by a AMS radiocarbon chronology. At both sites basal inorganic sediments (pre 13,830 cal. yr BP) are dominated by pollen assemblages indicative of open conditions, suggesting a stadial climate. Between c. 13,830 cal. yr BP and c. 13,000 cal. yr BP the accumulation of detrital mud and an increase in the pollen of woody taxa is interpreted as a period of climatic amelioration (the Lateglacial Interstadial). Inorganic sedimentation recommences and the pollen of woody taxa is reduced during the climatic deterioration of the Younger Dryas (after 13,000 cal.yr BP). However, macrofossil evidence suggests tree Betula may have been present during this cold stage. The onset of the Holocene is marked by an increase in Betula pollen at c. 10,800 cal. yr BP (Bridge Sollers) and c. 11,200 cal. yr BP (Stansbatch). The early increase of Juniperus communis pollen, seen in many British sites, is not detected. This may be the result of the presence of tree birch during the Younger Dryas. Corylus avellana appears to have arrived c. 10,500 cal. yr BP, Ulmus c. 10,100 cal. yr BP and c. 9,850 cal yr BP and Quercus c. 9,900 cal. yr BP and c. 9,700 cal. yr BP. Increases in Pinus sylvestris pollen c. 9,450 cal. yr BP and c. 9,800 cal. yr BP are probably the result of long distance transportation from the uplands. At both sites sediment accumulation ceases after c. 8,900 cal. yr BP, indicating drier conditions. Sedimentation recommences at Stansbatch during the mid Holocene when Tilia dominated the vegetation. A decline in Tilia pollen occurs at c. 3,700 cal. yr BP probably due to anthropogenic activity.

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