Wild trees are key to nature's future
Leac Doire Lochaidh, the ‘hillside of Lochy’s thicket’, supports the scattered remains of an ancient woodland above the Loch Cuaich dam. Every year, the massive alders and twisted birches that grow on these grassy slopes flower and set seed, giving rise to thousands of seedlings that would re-wood the surrounding area if deer numbers were lower. This ability to regenerate naturally is how tree populations renewed and expanded themselves for hundreds of millions of years – only in the last few centuries has planting by people become commonplace.
The trees of Leac Doire Lochaidh are wild, descended naturally from populations that recolonised Scotland soon after the last ice age. They provide an ecological and genetic link back to the original forests that once covered around 60% of the Highlands, and a cultural link to the people who named and valued the places where they grow. Research has found that these wild trees can have higher levels of genetic diversity than planted ones, making them more adaptable to intensifying threats from disease and climate change.
Wild trees are surprisingly widespread in the Highlands. Most glens have their own versions of Leac Doire Lochaidh, as well as crags and steep-sided ravines where rarer trees like aspen often grow. These refuges also support a wide range of other species that have been lost from the wider landscape, from mycorrhizal fungi and old-growth lichens to ancient woodland wildflowers and deadwood invertebrates. This makes wild trees good indicators for biodiversity more widely; they mark out areas where other threatened wildlife is likely to be present too.
Many wild tree refuges are threatened by centuries of heavy browsing pressure from livestock and deer, and some have been badly damaged by conversion to commercial conifer plantations. Each year that passes more are lost, and the opportunity to meaningfully restore our wild landscapes fades a little further. A major barrier to fixing this is that most of the effort going into expanding Scotland’s tree cover is heavily focused on new planting projects. Places that still support wild trees and their capacity for natural woodland expansion have been largely overlooked.
We can help turn this situation around by making wild trees a priority when planning and delivering rewilding projects. As a first step, we’ve been surveying wild trees across whole landscapes, tracking down surviving populations and identifying the most diverse and most threatened refuges. This allows us to see with clarity where we need to target our resources to enable natural woodland recovery and expansion. It also helps shift thinking towards long-term landscape-scale action, and flags dwindling populations of rarer wild trees like aspen, juniper, and montane willows. Some of these species have been reduced to tiny single-sex populations, meaning they may struggle to spread back out on their own.
Going forward, our planting projects will be designed to complement wild trees, being used to boost populations of struggling species and maintain their genetic diversity. They will also only take place in areas distant from seed sources after wild tree populations have already been secured. We hope to share this model of rewilding with other organisations and government departments, and put wild trees firmly on the policy agenda.
This is an exciting time for Trees for Life as we recalibrate our efforts to rewild the Scottish Highlands and restore the Caledonian forest. We will lead by example and work with others to ensure that wild trees and the places they grow are part of our wilder future.