Late-Quaternary Vegetation Dynamics of the Cairngorms

Abstract

Until about 15,000 years ago, the whole of the Cairngorms region was covered by part of an ice-sheet that extended across all of the northern British Isles. Our understanding of the development of vegetation following retreat of that ice comes from studies of fossil pollen preserved in peat and lake sediments, and from mapping and radiocarbon-dating of wood remains in peat. Initial plant communities were open, but woodland of birch (Betula spp.) spread rapidly across the landscape in the early Holocene, followed by pine (Pinus sylvestris). The origin of the pines that established woodland in the Cairngorms is currently unknown: a continental origin (via a spread through England and southern Scotland) or a west Scottish/Irish refugial origin are both possible. Woodland became established, with pine as the dominant, by about 8000 years ago, probably at all altitudes up to about 800 m. Birch, and hazel (Corylus avellana) on less acidic soils, would also have been present. At higher altitudes, plant communities are likely to have been always open, but there is no direct evidence for the Holocene development of vegetation at these altitudes. After about 3000 years ago forest declined regionally as a result of increasing anthropogenic pressures, and peatland ecosystems increased in areal extent.

Estimating past floristic diversity in montane regions from macrofossil assemblages

“…The reduction in abundance of remains of Betula and Pinus after c . 4500 14 C yr BP concurs with the general pattern of forest decline in the region at this time (Birks, 1975; Bennett, 1996) and the further decrease in tree abundance in the region after c . 3500 14 C yr BP (O’Sullivan 1974, 1975, 1976).…”

“…The record from Lochan Oir spans the last 8000 14 C yr, beginning at a time when Salix trees were growing in the lake depression with Betula and Pinus close by; this is in agreement with the widespread pine‐birch woodland vegetation recorded from the Cairngorms region at this time (Bennett, 1996). The reduction in abundance of remains of Betula and Pinus after c .…”

“…Where forests persist in the study area the tree line is at c . 490 m (Bennett, 1996), some 125 m below the highest extant Pinus sylvestris tree line in the Cairngorms (Pears, 1968). The relatively low elevation of the potential tree line (615 m), compared to the Norwegian study area, may reflect principally the influence of wind exposure; the tree line depression within the study area primarily may be attributed to browsing by red deer Cervus elephas L. In this area 328 quadrats were sampled by colleagues from the Institute of Terrestrial Ecology and 260 vascular plant species were recorded.…”

New Evidence for Upland Occupation in the Mesolithic of Scotland

“…An Ordnance Survey/EDINA supplied service) THE PREHISTORIC SOCIETY 2011,264). While areas of heather and grass existed at higher altitudes, all the archaeological sites discussed here were below the natural tree line (Bennett 1996).…”

Palaeoecological perspectives on Holocene environmental change in Scotland

“…Pears (1967, 1968) suggests that this is artificially low, and that the present climatically-potential tree-line would be at about 680 m altitude. Peat profiles show that pine reached 930 m altitude in the Cairngorms, and 600 m in the NW Highlands (Binney 1997), while fossil tree stumps have been found in peat at altitudes up to about 790 m (Bennett 1996). Former tree-lines have thus been higher than those of today, and radiocarbon-age determinations show that pine occurred at these higher altitudes several times during the Holocene, but not continuously (Pears 1975; Dubois & Ferguson 1985, 1988; Binney 1997).…”