Loch Ossian Plantations Corrour Estate - A Fresh look at species and growth. August 1982
Omorica spruce in Ossian Forest – Corrour Estate 1934
Photograph is courtesy and copyright of Forestry Commission, Forest Research, Roslin, and provided with help from Glen Brearley. FR Photo number No B2300 taken by J A B Macdonald.
The comments reads; ‘Omorica on a rather steep slope in Compartment XVIB. Sample No 227. Granite.’
This image above has been used to introduce a report written by the late John Keenleyside on the species planted by Sir John Stirling Maxwell around Loch Ossian from 1892 up to around 1956 and the survival and growth of those species. The text below is a transcript of the report as published in the Scottish Forestry Volume? Pages 275-280
LOCH OSSIAN PLANTATIONS, CORROUR, INVERNESS-SHIRE. A FRESH LOOK AT SPECIES AND GROWTH. AUGUST 1982
BY J. C. KEENLEYSIDE
Research and Development Division, Forestry Commission,
Newton, Moray
The Loch Ossian plantations lie on both sides of the loch near Corrour Lodge, sheet 42, 1:50,000 Ordnance map, grid reference NN412698. Corrour Station at the northern end of the Moor of Rannoch is the normal access point. The plantations are situated on both sides of a heavily glaciated valley occupied by Loch Ossian which is 391 m above sea level. Plantations extend up to 487 m. The climate is severe, ground conditions are poor, and Calluna check is a problem with heather sensitive species (spruces, Abies, Tsuga). Precipitation is 1670-1780 mm per annum; winter snowfalls tend to be heavy and prolonged. The relatively low summer temperatures also produce a significant shortening of the growing season. Surrounding areas of high ground give reasonable shelter. It falls in the zone MV: cool wet uplands of Birse and Dry (1970). Precipitation exceeds potential evapotranspiration in all months of the year. The main geological formation comprises quartzose rocks of the Moine series while extensive areas of granite lie to the south and east of the Loch. Mineral soils are mainly derived from glacial deposits which are markedly poorer to the north and west of Loch Ossian. Peat is present throughout but is generally fairly shallow except on the flats, mainly by the lochside.
History of the Plantations
The estate was purchased in I888 by Sir John Stirling Maxwell, who began tree planting around Loch Ossian in 1892 (Stirling Maxwell, 1951). Planting continued under his direction until his death in 1956, by which time the plantation area totalled about 283 ha. Sir John was one of the great pioneers of tree planting on peat. He planted over 70 different conifers and a number of hardwood species on difficult ground, with poor access and a short growing season. He experimented with manual site cultivation, planting on turves, and application of phosphate fertiliser. In the early days of the Forestry Commission much attention was paid to the work that had been done here. Many of the initial experiments at the Lon Mor in Inchnacardoch Forest were designed to follow up work done at Corrour.
Early unpublished reports by Mark Andersen (1928) and J, A. B, Macdonald (1934) examined the problems of establishment in great detail, looking at ground preparation, methods of planting and fertilising of trees. They studied the growth of the wide range of species planted and outlined the establishment difficulties. All species started very slowly and the establishment phase was prolonged. Photographs taken in the 1930s (on file at the Forestry Commission's Northern Research Station) show the plantations as being very patchy with the better growth on the slopes and poorer growth on the wet peaty areas.
Drainage systems were improved and planting on Belgian turfs became standard practice on wet peaty areas after a visit to Belgium in 1906. Systems for applying phosphate were developed in the 1920s. A series of top-dressing experiments was laid down with phosphate in the form of basic slag. The whole crop responded to treatment and gradually the poorer parts of the early plantations were treated.
In 1926, turf nurseries were developed. These consisted of turfs measuring 300mm x 200mm thick, cut from drains 0.9 m apart. A seedling or small transplant was planted in each turf and fertilised with 57 gm basic slag. After 2 years the whole turf was transferred to the planting site. Use of this system had the advantage that planting could continue over a long season. The disadvantage was the problem of moving the large turfs, but this did not deter Sir John and his staff. They even shipped turfs across Loch Ossian to afforest the other side. Including plants and slag, the completed cost of the plantations was not more than £20 per ha (1934 prices). With these improved techniques for establishing spruce, the species choice tended to change from Scots pine (Pinus sylvestris L.) to Sitka spruce (Picea sitchensis (Bong.) Carr.) on the wet peaty areas.
The planting and consolidation continued until 1939 when they claimed that practically the whole wood had been made good. Thinning commenced at this stage and pit props were produced for the war effort. Until 1952 moderate low thinning was practiced. In 1952 an arrangement was made with Professor M. L, Anderson, Edinburgh University, to put certain areas under the Method of Control or check method of management. The third cycle of measurements was completed in 197l (Malcolm, 1971).
The ownership of the plantations passed to the Forestry Commission in 1965. Further areas were ploughed and planted, mainly with Lodgepole pine (Pinus contorta Dougl.) and Sitka spruce, In 1982 the plantations returned to the ownership of the Maxwell-MacDonald family.
The present situation (1982)
There is an impressive forest area extending along both sides of the loch from its north-east end. Rates of growth are good and there are fine specimens of many different species. It is a productive forest, very pleasing to the eye and a marvellous monument to those who strove so hard during the establishment phase to create it.
SCOTS PINE: planted on a large scale in the early years on a wide variety of sites. It is likely to be of Strathspey origin and did not do very well on this difficult site type. Poor soils, exposure, short growing season and snow damage were all contributory factors. Many of the areas originally planted with Scots pine were later under-planted with Sitka spruce or Abies procera in the 1920's. Scots pine remaining from the early plantings have grown very slowly and are General Yield Class (GYC 4-6). Trees tend to have rough side branches and stag heads—signs of much snow damage. Scots pine suffered from the fact that much of it was in the early plantings with poor ground preparation and before the value of phosphate was appreciated. The combination of unsuitable provenances, poor ground preparation and little or no fertiliser at planting was responsible for Scots pine not being more widely used in later years.
LODGEPOLE PINE: only a small area planted. One lot of South Coastal type has grown vigorously but stem form is poor; it has very deeply fissured bark. The trees are becoming very unstable towards the upper planting limit, with very slow initial growth, GYC 6. An inland provenance probably from Skeena River has been severely damaged by deer for many years, and this has restricted growth to GYC 4. It is a pity that more Lodgepole pine had not been available when the early plantings were carried out. The coastal type tried here proved to be unstable and the Skeena River provenance was badly browsed by deer for many years. The total amount of Lodgepole pine in the early plantings was very small though this species was suited to many of the site types being afforested.
OTHER PINES: altogether 12 species of pines were planted. Survivors were found of 8 species but the only ones of possible commercial potential are:
Pinus monticola Douglas ex D. Don,: 3 specimens survive near the roadside at the Lap Burn, these are healthy trees with good stems and basal area.
Pinus peuce Griesbach: found in 2 locations. They have straight stems, good crowns and high basal area. They started very slowly, growing only 10-12 cm per annum, but in a second phase of growth, probably when Calluna had been suppressed, they began to grow at 20-10 cm per annum, and in recent years annual growth has been 30-50 cm per annum. This seems to be a pine which is worth further investigation.
LARCHES:
European larch {Larix decidua Mill.): some are very poor and others very good considering the location and climate. The best have very fine straight stems of good quality, and growth equivalent to GYC 8.
Hybrid larch (Larix x eurolepis A, Henry): only planted on a small scale but growing vigorously where found and apparently suited to the mineral soils and sides of knolls. Stems are not as fine as European larch, but growth rate is similar (GYC 8).
Japanese larch (Larix kaempferi (Lamb.) Carr.): growing well on the sides of knolls, they tend to have fairly straight stems with good form. Show a tendency towards hybrid vigour and form.
SITKA SPRUCE: is the most widely planted species here and it has grown well once it overcame the initial problem of Calluna check. Many fine specimen trees are present and some good stands of Sitka spruce timber have been produced, after much early difficulty with ground preparation and fertiliser regime. The growth is equivalent to GYC 12. The success of Sitka spruce here is due to the development of turf planting and the realisation that input of phosphate was necessary for initial establishment.
NORWAY SPRUCE (Picea abies)(L.)Karst.): tends to be extremely variable, especially on the deeper peats. It has been quite widely planted here and seems to have thrived once the Calluna has been suppressed. Growth equivalent to GYC 6-8.
OTHER SPRUCES: in all 19 different spruces were planted. Survivors of 9 were found. Apart from Norway spruce and Sitka spruce the only other spruce with commercial potential is Picea omorika.
Picea omorika (Pancic) Purkyne: trees tend to have very narrow crowns not more than 2m in diameter.They have very fine branches. Growth has been very steady but very slow. Growth equivalent to GYC 6.
Picea glauca (Moench.) Voss: was quite widely planted here. It suffered considerable deer damage, growth was extremely variable, and snow damage also occurred. Growth was less than half that of Sitka spruce growing adjacent to it.
SILVER FIRS:
Abies procera Rehder: is the most widely planted silver fir and was found in 10 different compartments. Growth tends to be variable. In some cases it was raised as an underplanted crop. It has grown well here and produced sawlogs which, whilst being large, are of low value, some showing signs of Fomes stains. It has stood up well to the exposure. One of the largest trees in the forest is an A. procera in Compartment 1a enclosure.
Abies grandis Lindley: found in 5 compartments. It has done surprisingly well here. In some cases it was introduced by underplanting, but height growth has been very vigorous and the trees are taller than any of the surrounding species. The top 5 m of crown is suffering from exposure. Crowns are very narrow at the top, only about 1 m diameter, but they still keep struggling to achieve greater height.
OTHER ABIES SPECIES:
Abies alba Miller: only a few survivors of this species. Early
establishment problems and Adelges attacks mean that survival was low.
Abies veitchii Lindley: good healthy specimens have occurred at 3 locations on the better soil types. The dark green foliage and pate grey smooth bark make this a very attractive tree.
There is a record of 21 Abies species having been planted. Only 6 of these were positively identified but this does not mean that 15 have failed. Some may have been cut in the fellings and others windblown. On the whole, Abies species have done better than one would have expected in this situation.
DOUGLAS FIR (Pseudotsuga menziesii (Mirb.) Franco: very few trees remain. They were found in 4 compartments. The trees which have survived are good trees and tend to be on the better sites with alluvial soils. The early planting of Douglas fir tended to be on unsuitable sites and some were of the Colorado (var glauca) type. This gave them a poor start and [ended to discredit the species.
TSUGA HETROPHYLLA (Raf.) Sarg: a few very good specimens of this
species growing on the better soils found in 3 compartments. They have
produced some very good straight stems with high sawlog content, A tree
which seems to struggle through despite adverse climatic conditions. They
seem to have grown well after suffering from deer damage in the early
years.
TSUGA (PATTONIANA) MERTENSIANA (Bong.) Car.: a few specimen trees but capable of growing to a good size and producing good sawlog timber. An attractive amenity tree where open grown.
ARAUCARIA ARAUCANA (Molina) K. Koch.: there are 7 survivors of this species which, although very healthy looking, have grown very slowly. Date of planting is not known but reported in 1934 to be 2-3 m tall (photo available), they are now only 3-7m tall 48 years later.
HARDWOOD SPECIES
The natural birch (Betula pendula Roth.) wood, which is unenclosed,
seems to have deteriorated from its condition as reported and
photographed in 1934. The birch have tended to become more flattened
on the tops and there is dieback of individual stems and branches. Of the
hardwoods around the lodge, rowans (Sorbus aucuparia L.) and alder
(Alnus glutinosa (L,) Gaertn. have deteriorated, showing signs of age and
exposure. Sycamore (Acer pseudoplatanus L,) has stood up well to
exposure, and there are some fine stems of beech (Fagus sylvatica L,) in
this area. Browsing by grazing animals (ponies, deer etc.) has been hard
on any potential regeneration of hardwoods in this area.
NATURAL REGENERATION
Where fellings or windblown gaps have occurred natural regeneration
of Sitka spruce has been good and Abies procera fairly good. Some
seedlings of Tsuga heterophlla have occurred in favoured locations,
mainly on mineral soil. Regeneration of larch is rare. There is little or no
regeneration of the many other species planted here.
Conclusions
Forestry in general today owes a great deal to the pioneering work carried out at Corrour.
The main advances were:
1. the use of Belgian turf system which enabled belter establishment of the wet peaty areas;
2. the knowledge gained in the use of phosphate fertilisers which sustained growth of these poor sites;
3. the change in choice of species from low-yielding Scots pine to faster-growing Sitka spruce;
4. the realisation of the problems of Calluna check in spruce and the many attempts to rectify this. There are plenty of examples of the benefit of mixtures in helping to overcome the difficulty;
5. The choice of species: from the wide range tried, Sitka spruce has emerged as the most adaptable and productive, Abies species have grown surprisingly well considering the poor site types and short growing season;
Lodgepole pine was poorly represented in the early plantings but grows well on such site types;
Pinus peuce is worth of further consideration. It grows slowly in the early stages but improves considerably once canopy has been formed;
Tsuga heterophylla is a persistent species and struggles hard under adverse conditions;
Picea Omorika is a slow but sure species with very narrow crowns.
REFERENCES
Anderson M L., (1928): Report on Loch Ossian plantations. Forestry Commission (unpublished ) 20pp.
Anderson M.L., (1953): Plea for the adoption of the standing control of check in woodland management Scottish Forestry 7, 38-47
BIRSE, F L., and Dry, F T. (1970): Assessments of climatic conditions in Scotland. Macaulay Institute 25pp. cent
Gorrie, K.M. (1954): The centenary excursion. Scottish Forestry 8 142-145.
Macdonald J.A.B. (1934): Loch Ossian Plantations. Silvicultural Studies No. 3. Forestry
Commission (unpublished) 79 pp.
Malcolm, D. C., (1971): Corrour management trial. Scottish Forestry 25. 262-270.
Stirling Maxwell, Sir J (1951): Loch Ossian Plantations. 3rd Edition. (Privately Printed).
Download Large Version (726kB)
Groups: Forestry Areas, Forestry Records, Booklets and Reports