Scotland’s missing habitat – restoring montane woodlands at Mar Lodge Estate

It’s a spectacular natural montane woodland habitat – unfortunately we’re not in Scotland, but in Norway. We’re here as a group of Cairngorm land managers to see and understand the large-scale spontaneous reforestation that has occurred in the last century in Norway and in particular to experience the high-altitude montane woodland habitat which grows there. This habitat is almost missing completely from Scotland. Montane woodland, often referred to as montane scrub or tree-line woodland, is the name for the habitat where trees grow at higher altitudes than the timberline (above which trees can no longer sustain an upright growth form with good-quality timber trunks) but beneath the tree-line (above which no tree species can grow, even the hardy willows, birch and juniper).

South-west Norway has many similarities to Scotland including the geology, topography, climate, habitats and species. Increasingly, ecological comparisons are being drawn between the two countries and questions asked as to why Scotland’s woodlands have not developed like Norway’s and more importantly could they, if appropriate conservation actions were taken here? For all of us on our trip to Norway, the answer was clearly yes and the visit was quite simply an inspiration!

The historical loss of montane woodlands in Scotland has primarily been at the mouths of grazers – deer, sheep and even mountain hares, although in certain areas climatic change and muirburn may also have contributed to their demise. In Scotland, montane woodland species (including juniper, dwarf birch, various willow species and high-altitude stunted birches and pines) generally only occur on inaccessible crags, riversides and steep slopes of mountains outwith the reach of grazing animals. Most populations are extremely small, isolated and fragmented, which often results in them being limited in their ability to naturally regenerate. Where species have survived in more accessible locations, they’re almost always heavily browsed and struggle to grow above the height of the ground vegetation.

Only one surviving example of true montane woodland habitat is recognised in Scotland – at Creag Fhiaclach on the western side of the Cairngorms. The precariousness of the remaining fragments of montane woodland was recognised at Ben Lawers over 30 years ago. Here, pioneering work was undertaken and continues today to propagate and plant out montane woodland species within fenced exclosures. This both protects trees from browsing and reinforces existing populations, allowing them to regenerate naturally and expand. The success of this work gives an indication of how Scottish mountainsides could look and is well worth a visit. Since then the Mountain Woodland Action Group has brought together expertise in the field of montane woodlands and has been a pioneering force in montane woodland restoration. Increasing concern about the future of relict montane woodland habitat in Scotland has resulted in further sites initiating conservation work to protect and enhance montane woodland species, such as Carrifran in the Borders and Coire Fee in the Angus glens.

Inspired by the visit to Norway, now 5 years ago, and the work at places such as Ben Lawers and Carrifran, the Cairngorm land managers group, including the Trust at Mar Lodge Estate, were motivated to bring about large-scale change across the Cairngorms for montane woodlands.

At Mar Lodge Estate we had little knowledge of the distribution and density of montane woodland species other than casual observations and occasional surveys which had been conducted over the years. However, since 2000 grazing pressure had been reduced significantly to allow the recovery and ongoing regeneration of the Caledonian pinewoods. Of course, this reduction in grazing pressure also benefits montane woodland species and increasingly we have observed willows, juniper and dwarf birches starting to emerge out of the heather all over the place, like a phoenix from the fire. This suggested to us that the estate had always had significant numbers of montane woodland species, but that they had been browsed down below heather height.

Before launching into any active conservation work, we decided to conduct a large-scale survey of the estate for montane woodland species to inform our thinking for conserving this habitat. So between 2016–18, supported by part-funding from the Cairngorms National Park, we commissioned an extensive survey across 15,500ha of the estate.

And what a turn up for the books this survey proved to be! The results showed that we had an extensive distribution of juniper, dwarf birch and a few of the willow species. The density and spread of these species was such that we felt there was no need to do any planting. With continued deer control these species should have the ability to regenerate naturally and expand without further intervention. We’re also now observing extensive pine and birch regeneration across the estate, so again, given time, these species should creep up the slopes, take on their stunted form at high altitude and start to contribute to the montane woodland habitat.

However, the survey did indicate that two willow species were extremely rare and in a fragile position. These two species – downy willow and whortle-leaved willow – are true montane willow species, only growing above 650m altitude in the high coires and crags of the estate. Just two populations of whortle-leaved willow were found and although eight populations of downy willow were recorded, a number of these were extremely small (less than five individual trees), isolated and with little capacity to regenerate naturally. This information sparked us into further action to improve their prospects and secure a positive future for these species on the estate. Our plan was quite simple. First, we would plant willows to reinforce these populations and hopefully give them the ability to reproduce and regenerate naturally. Secondly, we also wanted to create new stepping-stone populations between the existing ones, which would improve the likelihood of cross-pollination and successful seeding between the isolated populations.

Our hope was to use seed gathered from the Mar Lodge Estate willow populations to grow on trees to reinforce existing populations. This would involve using trees derived from seed of one isolated population to reinforce a different population, thus introducing new but local genetic material. Before doing this there was a need to consider the genetics of these fragmented willow populations. It’s likely they may have been isolated for centuries and possible that they were in fact genetically distinct from one another, therefore mixing the populations may not be advisable. Working in collaboration with the Royal Botanic Garden Edinburgh, Wildland Ltd (Glen Feshie) and RSPB Abernethy, we embarked on an analysis of the genetics of both downy and whortle-leaved willow populations from Mar Lodge Estate and these neighbouring estates. Fascinatingly, the results showed that there has been historical gene flow between all these populations, suggesting that at one time there was an almost more continuous spread of willows in the area – much like we had found on our visit to Norway.

The genetic analysis also indicated there was no risk in mixing genetic material from different populations, but rather that this would be recommended. This was good news and allowed us to go ahead with the Mar Lodge work as planned and also opened the door for potentially using willow material from Abernethy or Glen Feshie for future planting.

So where are we now ?

During the last couple of years we have successfully collected cuttings and seed from a good number of the downy and whortle-leaved willow populations. We’re working closely with Trees for Life at Dundreggan, who have been growing on the seed for us in their purpose-built nursery into trees ready to plant out. They’re also using the cuttings from Mar Lodge to establish downy and whortle-leaved willow ‘seed orchards’ of these miniature trees for us. These seed orchards will provide us with an ongoing supply of willow seed over the coming years so we can continue to grow on further trees for planting out.

The real excitement begins this spring when we’ll plant out our first 2,000 downy and whortle-leaved willow trees on the estate, both in new populations and reinforcing existing ones. This will be a challenge as we’ll be planting in extremely remote, steep and high-altitude locations on the estate, but it’s one we’re looking forward to. We’re taking a calculated risk as these trees will be planted with no protection from herbivores. However, we’ve chosen the planting sites carefully and are optimistic that the browsing levels at these sites are low enough for the trees to survive, grow and bolster the existing fragments. Fingers crossed!

And the story doesn’t end there. Conservation or restoration of habitats is a long-term process and not a quick fix. Over the coming years we’ll be continuing our work to conserve these two willow species and watching closely the recovery of all the other montane woodland species. Who knows, in years to come perhaps Mar Lodge Estate will once again remind us of those stunning Norwegian slopes.