Modern pollen rain in the northwest of the British Isles

Abstract

Modern pollen rain in three unforested regions in the northwest of the British Isles is investigated using surface sediments from 64 small lakes (mean size 1.5 ha). Pollen assemblages from Shetland and the Western Isles accurately reflect the predominance of blanket peat vegetation on the islands and combined frequencies for the three main taxa, Calluna vulgaris, Gramineae and Cyperaceae, exceed 65% at all sites. The proportion of tree and shrub pollen is small (7-24%). Variation in pollen representation is much greater in surface samples from Donegal, Ireland; tree and shrub pollen frequencies range from 12-52% and have a mean of 30.1%. Concentrations and accumulation rates indicate that the pollen production capacity of blanket peat vegetation is comparatively high and is within the range for boreal woodland. Pollen assemblages from remote Scottish islands are not overwhelmed by long-distance inputs; a mean of 11.3% on Shetland and 13.8% on the Western Isles is thought to have originated from off-island sources. Small lakes in a treeless landscape record regional pollen signals and recruit a large proportion of pollen from outside the immediate catchment areas.

Late Quaternary vegetation history of the Western Isles of Scotland

“…The status of other tree taxa can be deduced from pollen records. Differences between fossil and modern pollen frequencies for Quercus and Ulmus are similar to those for arboreal taxa that were undoubtedly present in the past (Table 5; Fossitt, 1994a). This is not true of all regions on the Western Isles; pollen frequencies do not support the local presence oi Pinus sylvestris or Alnus glutinosa in the Loch Buailaval Beag area at any time during the Holocene.…”

“…Moderately high tree and shrub pollen frequencies are difficult to interpret in relation to the extent of woodland cover (Fossitt, 1994a). Bennett et al (1990a) proposed that about half the landscape around Loch Lang was wooded and this is probably true of lowland regions of the Western Isles in general (excluding areas of standing water) when woodland was at its greatest extent.…”

“…There are a number of unifying features between the two sites, the selection of which was based on criteria outlined in Bennett et al (1992); the importance of comparable fossil and modern pollen sites is stressed in Fossitt (1994a). Both small lakes occupy rock basins at iow altitudes.…”

Upland agriculture and environmental risk: a new model of upland land-use based on high spatial-resolution palynological data from West Affric, NW Scotland

“…This contrasts with the heath and blanket peat (cf. Fossitt, 1994) dominating the lower hillslopes around Torran Beithe, where anthropogenic indicators occur only sporadically, possibly in the extralocal pollen rain .…”

Long-term approaches to native woodland restoration: Palaeoecological and stakeholder perspectives on Atlantic forests of Northern Europe

“…High pollen values for Calluna vulgaris (heather), Poaceae (grasses), Cyperaceae (sedges) and Potentilla-type (e.g. tormentil) reflect the local abundance of blanket peat (Fossitt, 1994) and acid grass communities, the latter especially on more minerogenic soils on knolls at Glenleraig, Ruigh Dorch and Loch a'Mhuilinn. Older samples record the loss of woodland cover at these three sites through the 17th to 18th centuries AD .…”