High elevation planting to expand forest cover above the current treeline
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About three-quarters of Scotland’s forested land is made up of non-native plantations, mostly Sitka spruce. In many upland areas, productive tree growth is limited above 300 to 350 meters elevation due to wind exposure, poor soils, and grazing. These conditions create fragile open land with slope instability, low biodiversity, and simplified landscapes. High-elevation planting aims to restore the natural transition zones, improve slope stability, and enhance habitat diversity and resilience.
Context:
The upper tree line and shrub zones are missing ecotones in Scotland and the UK overall. Centuries of deforestation, overgrazing by sheep and deer, and extensive planting of non-native conifer plantations at lower elevations have left these uplands dominated by open heath and grasslands, with only fragmented remnants of native pine, birch, rowan, and juniper. Ecologically, restoring woodland in this zone would enhance biodiversity by providing habitats for species such as capercaillie, black grouse, and woodland invertebrates, while improving ecological connectivity between lowland and montane ecosystems. Woodland expansion here also contributes to climate resilience, increasing carbon sequestration, stabilising soils, and reducing downstream flooding by regulating water flow.
Socioeconomically, forest restoration in the upper tree line supports rural diversification and long-term sustainability. While these areas are unsuitable for intensive commercial forestry—due to altitude and exposure—they hold value for ecosystem services, ecotourism, and low-impact industries. Community-led rewilding projects, such as those in the Scottish Highlands, have demonstrated that woodland restoration can create jobs in conservation management, wildlife guiding, and nature-based enterprises. Additionally, the recovery of woodlands can reduce the heavy costs of deer management and soil erosion, providing indirect economic benefits to both landowners and the public sector.
Culturally, the upper tree line landscapes are central to Scotland’s identity, shaping poetry, music, and collective memory. In the international imagination, the Highlands are often seen as vast moorlands rather than the wooded landscapes they once were. Restoring native woodland helps challenge this imagery, reconnecting people with the historic “Caledonian Forest,” long rooted in mythology and heritage. For local communities, it also means reclaiming cultural landscapes lost to deforestation and clearance, fostering a renewed sense of place and continuity between people and their land.
Problem Description:
On a 2-hectare site above a slope previously affected by landslide, high-elevation planting can address key ecological and landscape issues. The most urgent concern was soil stability: the lack of shrubs and trees have left the ground fragile, with shallow soils prone to erosion during heavy rainfall. The newly established woodland will help bind the slope through a choice of local species with different root system structures, reducing the risk of further landslip and protecting the woodland and infrastructures below.
Planting at this altitude also improves the visual quality of the treescape. Productive forestry in the area is dominated by uniform conifer plantations, which contrast starkly with surrounding moorland. Introducing a mix of native species creates a softer, more natural transition at the upper edge of the forest, enhancing the landscape character valued by both residents and visitors. At the same time, upland woodland expansion supports biodiversity and climate resilience. It provides habitats for species not well served by commercial plantations and connects fragmented ecosystems.
The main restoration challenges at this site are exposure, poor soils and bracken overgrowth, all of which threaten sapling survival. Careful species selection and protective measures have been central to minimise the risks.
Implementation Steps:
1. Identify suitable site(s) based on ecological, pedogeological, and socioeconomic benefit potential of restoration action (e.g. landslide-prone sites, especially if near rural settlements; sites of considerable interest for tourism; key locations for local and regional transport).
2. Species biodiversity baseline survey: Carry out a detailed species and habitat survey of the site to document current vegetation, soil condition, and potential natural regeneration before planting.
3. Species selection: Choose a diverse mix of native trees and shrubs of local provenance, ensuring complementary root structures (deep and shallow) to maximise slope stabilisation and ecological resilience.
4. Site preparation: Install square netting, hessian mats and willow cuttings on erosion-prone areas to protect bare soil, limit runoff, and create favourable microconditions for sapling establishment.
5. Logistics and timing: Secure plant material in advance and schedule planting during suitable weather, accounting for steep terrain and the need for helicopter access (where needed, it would be recommended) in high winds.
Stakeholder Engagement:
Local stakeholders were engaged through three dedicated workshops designed to ensure transparency and inclusivity in the planning of the high-elevation planting intervention. Although direct field visits to the steep and fragile site were not possible for safety and logistical reasons, participants were provided with a detailed visual presentation. This included photographs taken during ecological surveys and maps illustrating the landslide risk, helping to convey both the rationale and expected benefits of the restoration. Stakeholders were invited to share views and raise concerns, and all feedback collected was favourable, reinforcing local support for the intervention.
In addition to the local process, one workshop was held at the national level, bringing together representatives from government bodies, NGOs, and sectoral experts. This session placed the site-specific action within the broader project context, with a focus on opportunities to upscale similar restoration approaches. Several national stakeholders expressed interest in exploring feasibility pathways and emphasised the importance of integrating high-elevation woodland restoration into national policy frameworks. Their feedback highlighted the intervention’s relevance not only for soil stability and biodiversity but also for climate resilience and cultural landscape restoration, signalling potential momentum for policy alignment and wider replication.
Knowledge Types:
The high-elevation planting intervention builds on established technical and scientific knowledge of upland restoration in Scotland. Research shows that tree roots play a critical role in reinforcing soils on steep slopes by binding particles, improving infiltration, and reducing the likelihood of surface erosion and shallow landslides. A mixed composition of native species with different rooting depths—such as Willow, Sessile Oak, Downy Birch, Rowan, Alder —was selected to maximise these stabilising effects. This strategy reflects recommendations from Forest Research UK, including the report “Potential for woodland restoration above the A83 in Glen Croe to reduce the incidence of water erosion and debris flows”, which highlights how woodland establishment in erosion-prone areas can significantly mitigate slope instability.
Practical measures support ecological objectives. Square netting, hessian mats and willow cuttings were used to protect exposed soils, reduce runoff, and create favourable microsites for sapling growth, particularly important given the steep gradient and previous landslide activity, as well as the competition with bracken. Local provenance was prioritised in sapling sourcing to ensure genetic suitability to site conditions and resilience to exposure.
Implementation planning also considered operational constraints: helicopter access was required to deliver materials due to slope steepness and safety risks, and planting was scheduled during weather windows with reduced wind exposure. Together, these methods integrate ecological science, soil mechanics, and logistical planning, demonstrating how high-elevation woodland creation can provide long-term benefits for slope stability, biodiversity, and climate adaptation.
Replicability:
YES, the practice has been tested and replicated in multiple contexts and scales and therefore, can be easily transferred and/or adapted to other initiatives with similar goalsHigh-elevation planting has been successfully tested and replicated in several Scottish contexts. A major example is the Rest and Be Thankful project above the A83 in Glen Croe, where woodland restoration was implemented to reduce landslides and debris flows, safeguarding a key transport corridor. Similar approaches have been adopted on private estates in the Cairngorms (Mar Lodge Estate; Glen Feshie Estate) and the Scottish Borders (Carrifran Wildwood, Borders Forest Trust), often focused on native woodland recovery for both slope stability and biodiversity. Forestry and Land Scotland has also trialled high-elevation planting on exposed sites at Glen Affric, integrating protective woodland belts to manage erosion risks and enhance landscape resilience.
Key Success Factors:
Stakeholder engagement and social acceptance
Early and continuous dialogue with local communities and interest groups ensured positive reception for high-elevation planting. Workshops and consultations generated useful insights, such as retaining open areas to maintain important niches and panoramic views valued by walkers. This participatory approach enhanced the project’s capacity to balance ecological and cultural priorities.
Local provenance and ecological suitability
Sourcing native propagation material from local provenances ensured ecological fit and resilience to site conditions. It is hoped that this will increase survival rates under harsh climatic exposure and supported genetic diversity in the wider landscape. Using species with complementary rooting systems also maximise slope stabilisation benefits.
Cost-effective technical measures
Employing simple, affordable techniques such as hessian mats to reduce erosion, square netting for sapling protection, and willow cuttings for rapid rooting provided an effective and replicable model. These solutions lowered establishment costs while improving plant survival and soil stability, making the practice more viable for scaling in similar upland contexts.
Common Constraints:
Availability of local provenance seedlings
Sourcing sufficient native planting stock of local provenance was a constraint, given the limited supply chains for montane species. This was addressed through early coordination with nurseries and advance planning to secure material well ahead of the planting season, ensuring genetic suitability and alignment with restoration guidelines.
Challenging site logistics
The steep slopes, strong winds, and variable weather delayed the implementation. Careful scheduling to avoid unsuitable conditions and the use of helicopter transport for materials enabled safe, efficient operations. Protective measures such as hessian mats also reduced exposure risks to young saplings.
Herbivore pressure from grazing
High-elevation sites are often grazed by sheep, creating risk of browsing pressure on young trees. The newly introduced saplings are particularly attractive as fresh food sources. Mitigation in areas more prone to herbivores pressure might need protective fencing and site-specific planning to reduce grazing impacts (e.g. culling), ensuring sapling establishment while maintaining compatibility with traditional land uses.
Lessons Learnt:
A key lesson was the necessity of planning ahead for local provenance material. Demand for native montane seedlings often exceeds supply, so securing propagation material well in advance is essential. This ensures ecological suitability, improves survival rates in harsh conditions, and strengthens the restoration’s long-term resilience.
The project also showed the value of early and constructive stakeholder engagement. Workshops generated broad support and useful feedback, such as the importance of retaining some open areas for both ecological functions and the scenic value appreciated by walkers. Active involvement helped align ecological goals with social expectations.
From a technical perspective, the intervention demonstrated that simple, cost-effective protection methods—including hessian mats, willow cuttings, and square netting—can substantially improve establishment rates on exposed slopes. Their use balanced cost control with ecological effectiveness, making the practice more replicable.
Finally, logistical challenges underscored the need for flexible implementation strategies. Fair weather windows, steep terrain, and strong winds required adaptive planning, including helicopter support for transport. Addressing these constraints proved vital to safe and effective delivery.
Positive Impacts:
- Improved scenic beauty
- Increased connectivity
- Increased landscape diversity
- Increased plant, animal and fungal diversity
- Reduced risk for soil erosion, landslides, rockfalls, avalanches
The intervention delivered multiple ecological and social benefits, with several key impacts standing out. Most prominently, the planting reduced the risk of soil erosion, landslides, and rockfalls on a slope previously affected by instability. The use of species with complementary root structures, reviewed and validated by Forest Research experts, combined with hessian mats to limit surface erosion, enhanced slope stabilisation and soil health. Additional technical input from Forestry and Land Scotland guided the choice of hessian mats as a cost-effective solution tailored to the site’s constraints.
The project also improved the area’s scenic beauty and landscape diversity. Introducing a carefully selected mix of native trees and shrubs will create a more varied and natural treescape compared to monocultural planting. Retaining small open areas within the design further will diversify the visual character and ensure a landscape more resilient to changing climatic conditions.
In terms of biodiversity, the intervention will contribute to increased habitat diversity, including micro-habitats important for species adapted to upland environments. The biodiversity baseline survey provided evidence of current conditions, against which improvements in plant diversity can be measured over time. The expected increase in structural and species diversity is also anticipated to strengthen ecological connectivity in the wider landscape.
Negative Impacts:
- Reduced recreational value
- Reduced societal support
In this project, no direct reduction of recreational value occurred, as the site lies away from main walking routes. However, some concerns were raised by locals and visitors about altering the traditional moorland character into a more wooded landscape. Such changes could, in their view, make access more difficult for walkers and potentially reduce the availability of panoramic views. These perceptions highlight the importance of communication and stakeholder exchange to explain the rationale for restoration and ensure social acceptance of landscape transformation.
Media
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Upper tree line on hills around Loch Long in the Argyll region of Scotland
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