For his sabbatical last year, Principal Conservation Scientist Ron Summers carried out a survey of the remaining fragments of Caledonian pinewood in Highland Scotland. His aim was to observe management features that may be compromising the potential for the old pinewoods to expand, as well as noting the features that are affecting the integrity of the pinewoods.    

The Caledonian pinewoods of Highland Scotland represent a rare (179 km2) and unique habitat, originating from woodland that established on these sites after the last glaciation. Many are at the old-growth stage of forest development, containing trees that are over 400 years old. Although many have had a history of felling, recovery of woodland has been by natural processes, so that these woods are as close to being natural as is possible within the UK. This habitat is recognised for its biodiversity, and historic, genetic and cultural values, resulting in a range of conservation designations (SSSI, NNR and SAC).

Plans were put in place in the 1990s to expand this habitat, primarily by natural regeneration and to remove the effects of inappropriate past management, such as the underplanting of Caledonian pinewoods with non-native conifers (e.g. Sitka spruce and lodgepole pine). In some cases, non-native conifers overtopped the old pines and killed them by shading.

The survey

To check the status of the core areas of Caledonian pinewood (the existing old pinewoods) and note features that may influence expansion into the regeneration zone (100 m out from the core) and buffer zone (500 m out from the regeneration zone), almost all 84 Caledonian pinewoods, as listed and mapped by the 1994 Caledonian Pinewood Inventory, were visited in 2021.

It was found that plantations of non-native conifers occurred in 39% of the regeneration zones (Photograph 1), 35% had old Scots pine plantations (Photograph 2) and 27% had new native woodland. An additional 30% of sites, that had no plantations in the regeneration zone, had plantations in the buffer zones. Thus, the extent to which Caledonian pinewoods could potentially expand naturally is being compromised.

Photograph 1. Caledonian pinewood at Cougie with planted Sitka spruce and lodgpole pine on the opposite side of the track. Both non-native conifer species were also establishing within the Caledonian pinewood through self-seeding © Ron Summers.

Photograph 2. Scots pine plantation adjacent to Caledonian pinewood in Glen Feshie. There are also old pines within the plantation showing that Caledonian pinewood was interplanted with Scots pines. Note too, the recent natural establishment of young Scots Pines amongst the old pines © Ron Summers.

Self-seeded non-native conifers or rhododendrons occurred in 39% of core areas of Caledonian pinewoods (Photographs 3 and 4), and 14% had planted native species (Photograph 5), compromising the integrity of the cores.

Photograph 3. A young Sitka spruce establishing beside and old Scots pine in Caledonian pinewood in Glen Einig © Ron Summers.

Photograph 4. Rhododendron ponticum in Caledonian pinewood at Loch Leven Caledonian pinewood © Ron Summers.

Photograph 5. A high density of young Scots pines planted after mounding in core Caledonian pinewood at Strath Vaich © Ron Summers.

An overhaul of the policies and government grant schemes that govern Caledonian pinewoods is required, because the management of many sites is not serving the conservation of these pinewoods which, unlike planted woodlands, have largely developed by natural processes over millennia and have a history of adaptations to the local environments.

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