Ben Lomond environmental study

Palaeoecology of the NTS Ben Lomond Reserve

Dr Eileen Tisdall and Dr Richard Tipping, Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling.

Introduction Reconnaissance on 19th September 2017 located a deep (>2m) valley mire east of Coire Corrach on level ground on the watershed between the head of the Ardess Burn and Wood Burn in Caol Ghleann at around 230m OD (NS 37432 99068). The mire is only c. 10m wide, very close to dry soils of the Ben Ledi Grit and sheltered below higher ground to north and south. The site probably receives most pollen from the immediate surroundings. There is no evidence for peat-cutting. This project is of relevance and interest to NTS and also makes a significant contribution to Scottish vegetation and land use histories.

Proposal Natural woodland at this altitude in the past would have had much of the diversity of the lowland. We might imagine a birch and hazel-rich oak wood. The history through the last c. 11700 years, the present interglacial, of oak-rich woodland along the shore of Loch Lomond was described from radiocarbon dated pollen records at the Dubh Lochan (NS 377 963) by Stewart, Walker and Dickson (1986). They described the sequence of tree migration in the first 5000 years of the interglacial. We are unlikely to improve on this record at Coire Corrach. What Stewart et al (1986) then described is an extraordinary persistence of oak woodland along the shores of the loch to the present (see also Tittensor 1970). Though not unique, the preservation/conservation of native woodland is exceptionally rare in Scotland, particularly when compared to nearby pollen records at the south end of Loch Lomond (Dumayne-Peaty 1998; Ramsay 1995) which describe nearly complete woodland loss by people in the later Iron Age c. 300 BC (see Tipping and Tisdall 2006). The reasons the woodland survived along Loch Lomond are not made clear by Stewart et al (1986). It may be that the limited extent and quality of farmable soils inhibited prehistoric settlement or that the economic value of the lowland woods was recognised at a much earlier date than Tittensor (1970) suggested. Above the shore, the slopes of Ben Lomond are treeless save for scrub in gullies. Woodland will have been the natural habitat, but it was not preserved or conserved. This is a more typical highland landscape. I would like our project to focus on the chronology and style of woodland loss around Coire Corrach, and by extension, the hills around Loch Lomond. Establishing these would contribute to future land management of the hills, reveal how they were used in the past and throw light on the persistence of woodland at lower altitudes. It is possible to recognise two styles of anthropogenic woodland loss: climate and pedological change will probably have played no roles in this on Ben Lomond. The first is a slow, gradual reduction in tree regeneration from sustained, but not necessarily high grazing pressures, from the Bronze Age c. 2000 BC to agrarian re-structuring in the 18th century AD. We might call this 'highland' woodland loss. A second, 'lowland' style is the maintenance of woodland, albeit used in short-lived incursions, until abrupt felling of whole landscapes in the later Iron Age c. 300 BC to generate for the first time an agricultural surplus (Tipping 1997). This style is confined to southern and central Scotland. Ben Lomond is on the border-line.

Proposed work

1. Probing of the interfluve peat will establish the pattern of peat growth and spread, and identify the deepest and oldest peat. Sampling on the same day will retrieve 1.0m lengths of this peat in plastic gutters.
2. After sampling, we need to radiocarbon date the basal peat to establish a sub-sampling strategy for pollen analyses. The turn-around time is c. 3 months. Peat cores will be kept in a cold store.
3. Pollen analyses will commence at a depth corresponding to the last period that undisturbed natural woodland might be expected to have grown, c. 6000 years ago (Tipping 1995) if the peat is of this age. It may be that peat inception itself was a consequence of increased water-logging of soils during woodland loss.
4. Pollen analyses are from 0.5cm slices of peat, mixing pollen accumulated over, roughly, a decade. A total of 300 pollen grains from dryland plants will be achieved, a statistically representative sum. Analyses will have to be at a low temporal resolution, perhaps one sample per 100 years and a total number of