Palaeoecological investigations towards the reconstruction of the post‐glacial environment at Lough Doo, County Mayo, Ireland

Abstract

Results of palaeoecological studies involving pollen analytical, chemical and palaeomagnetic investigations on a 3 m core from Lough Doo, NE County Mayo, are presented. The record, which commences shortly after 7000 BP, shows a sharp Alnus expansion coinciding with a decline in finus at 6400 BP, an elm decline taking place in the context of severe soil erosion and the final decline of Pinus occurring as the chemical record indicates onset of severe reducing conditions in the catchment. Pine becomes extinct at or shortly before 3200 BP in the context of increased farming activity and the expansion of blanket bog in the adjacent upland areas. A later feature (c. 1880 BP) is the expansion of Taxus to 7.1 % of total pollen.On the basis of the palynological evidence, it is concluded that there were no major Neolithic Landnam phases, which contrasts sharply with the evidence for widespread woodland clearance and the laying out of extensive and regular field systems in the northern coastal part of County Mayo. In the upper part of the core a severe inversion of I4C dates is recorded. O n the basis of the palaeomagnetic and pollen evidence this began at c. 1500 BP and is considered to have been initiated in the context of woodland clearance and a renewal in farming activity. v Journal of Quaternary Science

Taxus baccata L.

“…Periods of expansion of yew in Ireland around 1880 yr  (following an elm decline period) and a sharp decline around 1500 yr  have been found in a number of studies (Watts 1984;O'Connell et al 1987;Mitchell 1988Mitchell , 1990a, the decline corresponding to a rise in anthropogenic indicators (see also Willerding 1968). Its current restricted distribution in western Ireland represents the vestiges of a previously more widespread tree; indeed County Mayo (Maigh Eo) translates as 'the plain of the yew' (Symes 1879).…”

“…Periods of expansion of yew in Ireland around 1880 yr bp (following an elm decline period) and a sharp decline around 1500 yr bp have been found in a number of studies (Watts 1984; O’Connell et al . 1987; Mitchell 1988, 1990a,b), the decline corresponding to a rise in anthropogenic indicators (see also Willerding 1968).…”

“…Hist. ), reaching the limestone of north‐west England nearly 7000 years ago (Birks 1982) and moving into Ireland in the Atlantic and Sub‐Boreal, before 6000 yr bp (O’Connell et al . 1987, 1988; Mitchell 1988, 1990b).…”

Unusual mid-Holocene abundance of Ulmus in western Ireland-human impact in the absence of a pathogen?

“…In other parts of western Ireland, notably on acidic, rocky and infertile soils, elm was never abundant, with typical values of 3-10%, declining to 1% or less at the elm decline (Molloy and O'Connell, 1987). The record from Lough Doo in Co. Mayo (O'Connell et al, 1987) shows a rather gradual decline from nearly 10% at about 4900 14C yr BP to less than 2% by 3500 BP, and a subsequent fall to still lower abundance at about 1700 14C yr BP. On Inis Oirr, an island less than 10 km from the Clare coast and about 30 km northwest of Molly's Lough, Ulmus pollen seldom exceeded 10% in the early Holocene (Molloy and O'Connell, 2004).…”

Long-term human impact and environmental change in mid-western Ireland, with particular reference to Céide Fields – an overview

“…1a), provide no evidence for a pine flush though Pinus is well represented in the upland lakes, L. Corslieve and L. Aisling (Bradshaw and Browne, 1987). Nor does a pollen profile from L. Doo, 11 km south-west of Carrownaglogh, record a pine flush (O'Connell et al, 1987), probably because of a lack of bog development in the vicinity of the lake.…”