Human impact on the vegetation of South Wales during late historical times: palynological and palaeoenvironmental results from Crymlyn Bog NNR,West Glamorgan,Wales,UK

Palynological and palaeoenvironmental analyses of Crymlyn Bog, a lowland fen in South Wales, reveal insights into the effects of documented industrial activity on the landscape during the last c. 500 years. The pollen and palaeoenvironmental profiles suggest that a predominantly wooded landscape in which some agriculture but little industrial activity took place, occurred between the sixteenth and early eighteenth centuries. Significant increases in heavy metals, spheroidal carbonaceous particles and SIRM are coincident with rapid and substantial industrialization of the Lower Swansea Valley from the mid-eighteenth to early nineteenth centuries, although the pollen evidence suggests that the vegetation of the area was dominated by birch-hazel woodland. The pollen profile suggests that large-scale woodland clearance, that was perhaps caused by increased land-use pressure adjacent to the mire, occurred in the late nineteenth and early twentieth centuries. At the same time, decreases in the profiles of copper, zinc and lead reflect the decline of non-ferrous metal smelting in the Lower Swansea Valley. The spheroidal carbonaceous particle and SIRM profiles from Crymlyn Bog do not correspond with the national trends depicted in such profiles from elsewhere in the British Isles, probably because of the dominance of locally derived industrial pollution. The apparent integrity of the copper, lead and SIRM profiles suggest that fen peat is an eminently suitable, and thus much under-used, medium from which to reconstruct palaeoenvironmental and industrial histories. Limitations in the use of the zinc, and the SCP and pollen profiles as palaeoenvironmental indicators and dating tools respectively are demonstrated by the lack of correspondence between their profiles and documented historical land-use records.