Information and Advisory Note Number 108                                    Back to menu

Fire in the uplands: a historical perspective

1. Introduction

1.1 It sometimes seems to be assumed that fire is a relatively recent impact on the British upland scene, primarily associated with the expansion of game management in the latter half of the 19th century, having been little used before then. Also, that natural fire is so unusual in the British Isles as to be almost irrelevant.

1.2 We do not yet know enough about fire in the past to make detailed, definitive statements about changes in fire frequencies and, especially, changes in fire severities. However, both natural and deliberately set fires have occurred in many areas throughout the post-glacial period. Historical and palaeoecological studies show that fire has been a very long-established part of both the natural and cultural heritage.

1.3 Over the post-glacial period biological communities have not been constants but have continually changed in response to changing climates, soil development processes, and individualistic expansions and contractions of species ranges (Huntley & Webb 1988, Bennett 1997)This period is also at the lower end of time spans over which evolutionary change can occur (Bennett 1997). Fire has been a potential influence on these processes throughout this period.

1.4 The rest of this Note provides evidence in support of this historical perspective.

2. Fire occurrence during the last 11,000 years

2.1 Charcoal deposits in cores taken from loch sediments and peat bogs from many parts of Scotland show that fire has occurred in many areas throughout the c. 11,000 calendar years of the post-glacial period (Holocene). Fig. 1 shows some examples. At many sites fire activity appears to have been greater during various prehistoric periods than during recent centuries. Large amounts of charcoal are often found in early Holocene sediments. However, at some sites (e.g. Fig. 1 f) fire has only occurred to a significant extent during the last millennium.

2.2 A study recently commissioned by SNH (Bennett & Hill 1998), from near Ardheslaig on the Applecross peninsula, illustrates the degree of temporal variation in fire activity which can often be seen in charcoal records. Sample sediment cores were taken from a small loch and nearby small bog within 100 m of the loch. The first occurrence of charcoal in the loch record was from about 11,700 calendar years ago. The charcoal records from both the loch and the bog showed that fire occurred throughout the Holocene. Peaks in the loch charcoal record corresponded to fire activity at the following times: major maxima at c. 8636 years, c. 5670 years, and c. 5560 years ago; and lesser maxima at c. 11,710 years, c. 6930 years, c. 6010 years, c. 4360 years and at c. 380 years ago. Fire activity appears to have been most pronounced during the period between about 5670 years and 4360 years ago. The bog charcoal record was somewhat more continuous and showed greater charcoal deposition in recent millennia than was the case for the loch.

2.3 Such charcoal records probably record a variety of fire types from camp-fires to landscape-scale fires for clearance purposes and pasture management (Edwards & Whittington 1997). Even in the earliest Holocene, Mesolithic hunter-gatherers were probably present in many places. However, natural lightning fires cannot be completely discounted. In the early Holocene the climate was probably warmer and drier (more continental) than now (Briffa & Atkinson 1997) and lightning fires might have been more frequent. Fire occurrence in recent centuries



2.4 Contrary to popular belief, in the latter half of the 19th century rates of burning were not necessarily much higher than today. At the beginning of the 20th century The Committee of Inquiry on Grouse Disease took evidence from a wide range of moor owners, shooters, keepers, shepherds and sheep farmers, including evidence on burning (Lovat 1911). The conclusions were that from 1800 to 1850 heather moorland was burnt in wide tracts by the shepherds, with about a tenth of the ground being burnt per year on average. This was often stipulated in the tack, or lease. From 1850 to 1873 keepers became responsible for burning on many moors and since, in this period, tall heather was thought better suited to shooting over dogs (which was the norm at the time) the extent and frequency of fires dropped considerably, possibly by a factor of ten. In the last quarter of the 19th century the rate of burning increased somewhat, possibly to an average return period of about 30 or 40 years. It did not return to the 10-12 year rotations favoured by sheep farmers despite the fact that this would also have benefited the grouse. This was because many landowners mistakenly gave greater priority to size of patch burnt than to total area burnt.

2.5 Acts of the Scots Parliaments (Tait 1928) provide documentary evidence of muirburn as far back as the early 15th century. The provisions of these statutes were mostly concerned with preventing damage to woodland. Frequent re-enactments suggest that fire could have been frequent and controls ineffective. However, baron court records indicate that, at least in some places, statutes controlling 'muirburn' were rigorously enforced (Whyte 1979, Steven & Carlisle 1959). Interestingly, documents from the 17th century distinguish between burning of 'muirs', or hill pastures with a shallow layer of peat, and 'mosses' with a considerable depth of peat (Whyte 1979). This may indicate some sophistication in the use of fire.

2.6 Pinewoods are probably the type of woodland most likely to have experienced fire as a recurrent phenomenon because of their relatively flammable composition. However, studies of pinewood fire histories are almost non-existent. A recent study in the Black Wood of Rannoch (Snodgrass 1996) has shown, from analysis of the charcoal record in mor humus cores, that fires have been a recurring feature during the last couple of centuries. There was a large fire in the mid-19th century and another in the mid-18th century. However, at least some parts of the wood appear to have escaped fire for at least 200 years. Steven & Carlisle (1959) mention specific, usually large, fires in the 18th, 19th and 20th centuries in specific native pinewoods.

3. Fire history in the 20th century

3.1 The occurrence of fire has been, on average, moderately infrequent in the period since 1945. In the former local authority regions of Grampians and Borders a study of post-1945 aerial photographs (Hester & Sydes 1992) showed that the average frequency of fires, and the total areas of ground burnt, had been much lower than the traditional ideal for grouse or sheep management. On average only 1 - 2% of heather was burnt per year as opposed to an ideal of 6-10%. Similarly, detailed mapping of post-1945 fires over about 9.5 km² of Tulach Hill, near Blair Atholl in Perthshire, again based on aerial photograph interpretation, showed that on average only 1.2 % of the moor was burnt per year (Rhodes 1996).

3.2 These average rates of burning can disguise sometimes quite considerable variations in fire histories between patches. The results from the detailed mapping of fires at Tulach Hill illustrate this (Table 1).



On eastern, heather-dominated moors 90% of fires remain distinguishable on aerial photographs after 8 years (with 49% still visible after 11 years). Tulach Hill has an exceptionally good aerial photograph coverage (1950,1959, 1965, 1969, 1976, 1980,1985, 1988) which enabled a reliable post-1945 fire history to be determined. This also allowed testing of fire histories reconstructed from fine resolution analysis of charcoal deposits in mor humus cores (Rhodes 1996, Stevenson et at 1996).

3.3 Fire activity has probably declined over the last hundred years. A study of fire histories at five sites in eastern Tayside (Stevenson et al1996)using aerial photographs and mor humus charcoal records, showed that burning was probably more intense pre-1945. However, despite this, the study also demonstrated that there were stands at each site which had not been burnt since about AD 1800.

4. References and further reading

Bennett, K.D. (1997). Evolution and Ecology: The Pace of Life. Cambridge University Press.

Bennett, K.D., Boreham, S., Sharp, M.J. & Switsur, V.R. (1992). Holocene history of environment, vegetation and human settlement on Catta Ness, Lunnasting, Shetland. Journal of Ecology 80, 241-273.

Bennett, K.D., Fossitt, J.A., Sharp, M.J. & Switsur, V.R. (1990). Holocene vegetational and environmental history at Loch Long, South Uist Western isles, Scotland. New Phytologist 114, 281-298.

Bennett, K.D. & Hill, K.T. (1998). Vegetation and fire history in Applecross, north-west Scotland, during the Holocene. Scottish Natural Heritage Research, Survey and Monitoring Report No 108.

Briffa, K. & Atkinson, T. (1997). Reconstructing late-glacial and Holocene climates. In Hulme, M. & Barrow, E. (Eds.), pp 84-111, Climates of the British Isles. Present, Past and Future. London: Routledge.

Edwards, K.J. & Berridge, J.M.A. (1994). The late-Quatemary vegetational history of Loch a'Bhogaidh, Rinns of Islay S.S.S.I., Scotland. New Phytologist 128, 749-769.

Edwards, K.J. & Whittington, G. (1997). Vegetation change. Ch. 5, pp 63-82, in Edwards, K.J. & Ralston, I.B.M. (Eds), Scotland: Environment and Archaeology, 8000 BC - AD 1000. John Wiley & Sons, Chichester.

Edwards, K.J., Whittington, G. & Hirons, K.R. (1995). The relationship between fire and long-term wet heath development in South Uist, Outer Hebrides, Scotland. In Thompson, D.B.A., Hester, A.J. & Usher, M.B. (Eds.), pp 240-248, Heaths and Moorland: Cultural Landscapes, Edinburgh: HMSO.

Hester, A.J. & Sydes, C. (1992). Changes in burning of Scottish heather moorland since the 1940s from aerial photographs. Biological Conservation 60, 25-30.

Huntley, B. & Webb, T. Ill (Eds.) (1988). Vegetation History. Handbook of Vegetation Science No. 7, Dordrecht: Kluwer Academic Publishers.

Lovat, Lord (1911). Heather-burning. In 7?7e Grouse in Health and in Disease, Chapter XV!II, pp392-412, Committee of Inquiry on Grouse Disease, London: Smith, Elder & Co..

Rhodes, A.N. (1996). Moorland Fire History from Microscopic Charcoal in Soils and Lake Sediments. PhD Thesis, University of Newcastle upon Tyne.

Snodgrass, J.M. (1996). An Investigation of the Fire History of the Black Wood ofRannoch. BSc Thesis, Institute of Ecology and Resource Management, University of Edinburgh (copy held in SNH library).

Steven, H.M. & Carlisle, A. (1959). The Native Pinewoods of Scotland. Edinburgh: Oliver & Boyd.

Stevenson, AC, Rhodes, A.N., Kirkpatrick, A.H. & MacDonald, A.J. (1996). The determination of fire histories and an assessment of their effects on moorland soils and vegetation. Scottish Natural Heritage Research, Survey and Monitoring Report No.16.

Tait, J.H. (1928). The Game and Fishing Laws of Scotland. 2nd Edition. Edinburgh: W. Green & Son Ltd.

Tipping, R. (1995). Holocene landscape change at Cam Dubh, near Pitlochry, Perthshire, Scotland. Journal of Quaternary Science 10, 59-75
.
Whyte, I. (1979). Agriculture and Society in Seventeenth-Century Scotland. Edinburgh: John Donald Publishers Ltd.

5. Acknowledgements

Comments were kindly provided by SNH colleagues John Gordon, Andrew Coupar and Helen Armstrong, Alistair Hamilton of Edinburgh University, and Keith Bennett of Cambridge University.

6. Author

Angus MacDonald
Uplands Group, Advisory Services
Scottish Natural Heritage
2 Anderson Place
EDINBURGH
EH6 5NP
Tel: 0131-446 2474

7. Appendix

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