Testing Interventions

Cairngorms Connect is the largest habitat restoration project in Britain. This inevitably means we are breaking new ground, as we overcome barriers in the way of large-scale habitat restoration. Many of the challenges we face, could be addressed with a range of forms of management. Often, there is no clear evidence supporting one approach over another.

We need to ask the question "Which techniques work best, or are the most cost effective?" Where this is uncertain, then it makes sense to formally compare different management approaches side by side – testing different interventions within carefully designed field trials through our Seed Source Establishment Trial, Deadwood Creation Trial, Restoring Rare Plants and Cattle-grazing and Cutting Trial

Seed Source Establishment Trial 


Image (above): Staff and consultants involved in monitoring woodland expansion in the Cairngorms Connect area, sharing knowledge about monitoring approaches.

Re-establishing native woodlands by natural regeneration relies on nearby existing woodland to provide a source of seed. This can be a very slow process in remote and higher altitude areas, which are so distant from seed sources currently. Therefore to speed up the process in such remote areas, we are planting and sowing small pockets of trees to establish an initial seed source, from which natural regeneration can then occur.  

To work out how best to use this assisted regeneration method, we are comparing different options in a controlled management trial, replicated at nine sites across the woodland expansion zone. We are comparing two methods of ground preparation: cutting the field layer with a traditional flail mower, vs cutting with a robotic cutter, with both methods designed to open up the ground layer to provide better conditions for young trees to establish. Alongside this, we are testing the effectiveness of sowing seeds vs planting saplings. We are comparing all combinations of these cutting and sow/planting treatments, as well as comparing with areas subject to no management at all. This trial will focus on downy birch, aspen and eared willow and is taking place at RSPB Abernethy.   

Deadwood creation trial 

51048619858_23496f8baa_kImage (above): Ring-barking Scots pine tree using hand tool as part of restructuring work in Abernethy Forest. Our Deadwood Creation Trial will compare this and other methods of deadwood creation by management (e.g. winching, felling), to see whether they differ significantly in their benefits to deadwood beetles.  

This project is using an experimental setup to compare how different methods of active deadwood creation influence the deadwood beetle community. We are comparing three commonly used techniques: 

We are monitoring deadwood beetle abundance and diversity throughout the summer, both before and after deadwood creation, in each treatment type, as well as in ‘control’ trees that will remain alive throughout the project. We will repeat this monitoring for several years after deadwood creation to help us understand how the different methods of deadwood creation influence the deadwood beetle community over time.  

Trials of approaches to restoring rare plant populations 

We are working on two projects to explore how best to restore missing plant species - Twinflower and Montane Willow species. 

Twinflower Project 

51049363356_2a45ec4241_kImage (above): Twinflower, Linnaea borealis. One of our “Testing Interventions” projects will compare how twinflower seed production compares between patches that are, or are not, supplemented with transplanted twinflower individuals from elsewhere.  

Twinflower (Linnaea borealis) is a nationally scarce but declining understory dwarf shrub found only in the north of Britain. The loss and poor management of its native woodland habitat has led to a 44% decline since the 1970s and it is now confined to just a few hundred sites in Scotland, mostly in ancient pinewoods in the north-east of the country with particular strongholds in Strathspey and Deeside. We are working to establish new twinflower populations within the Cairngorms Connect area, as well as bolstering some existing populations to help ensure their survival. 
If you’re out in the pinewoods in summertime you might be lucky enough to see a patch of this beautiful wee plant at its prettiest – watch out for their delicate pink flowers growing in a pair on a long stem (but only 5 to 10cm high) above the branched network of stems bearing opposite pairs of leaves. If you see one, the chances are you’ll see a whole patch. But here’s the thing: that whole patch – even if it’s several metres across – could actually all be just one individual! This is where our conservation efforts come in. One of the things that makes twinflower particularly vulnerable to extinction in Scotland is the fact that it reproduces mainly by vegetative spread (rather than sexual reproduction) – meaning that most plants in a patch of twinflower are just clones of each other. In fact, most of the remaining patches in Scotland are made up of just one or two individual clones each. However, to be able to spread and survive in the long term, twinflower need to be able to reproduce sexually with different genetic individuals by producing seed.  
Thanks to extensive work by others in the past, we now have a good understanding of the genetic make-up of most of the populations of twinflower present in the Cairngorms Connect area and elsewhere in Strathspey. In this project, we are translocating additional clones to existing patches to increase the number of genetically distinct individuals, as well as establishing entirely new populations in suitable habitat within the pinewoods of the Cairngorms. The first translocations were carried out in autumn 2019 and our vision is to see twinflower once again become an everyday part of the Scottish pinewoods.  

Willows Project

51279308735_52dda4c9e5_cImage (above): Downy Willow (Salix lapponum) being carried into a site above Loch A'an for planting. 

Montane willows extremely rare shrub used to form much of the habitat known as montane scrub and is a reminder that the Cairngorms was once a stronghold of this specialist type of woodland, which occurs high up the mountains in-between the more familiar pine forests and the extreme harshness of the montane plateau. Now only a few scattered montane willow plants remain on cliffs edges and along steep burns, where they are inaccessible to grazing by deer and other animals, but it is hoped our new initiative will soon see the revitalisation of this largely missing habitat to the Cairngorms, and visitors to the high tops will once again be able to experience this rare and fragile habitat.  
Surveys and monitoring data has given us a better understanding of the distribution and populations of montane willows across the Cairngorms Connect area. As part of our genetic rescue work, we are focusing on two key montane willow species: Downy Willow (Salix lapponum) and Whortle-leaved Willow (Salix myrsinites). 
We found only one female plant of Salix myrsinites on the crags above Loch Avon and 37 individuals of Salix lapponum spread across 5 sites. Further genetic studies with the Royal Botanic Gardens Edinburgh, allowed us to determine which individuals should be grown from cuttings and then used as part of the translocation work by planting a mix of male and female clones in relatively close proximity to encourage cross fertilisation and seed set.  
This work has given us better information to determine which males and females to cross in the tree nursery to set seed so that we can bulk up numbers for propagation purposes over the next few years. Production from seed will maximise the genetic variation creating a larger number of unique genetic individuals.

Cattle-grazing and cutting trial

cattle at abernethy

Image (above): Some of the cattle that have been brought in to the ancient pinewoods of Cairngorms Connect as part of the Large-scale Field-layer Disturbance trial. The cattle are kept in part of Abernethy forest during autumn to late winter. There are two other areas in the trial: one kept unchanged (a “control” plot) and one that is having patches of vegetation mown with cutting machinery.  

Natural forests are characterised not just by their species, but also by their ecological processes; these can include disturbances created by wild grazing mammals, or natural fires started by lightning. These disturbances are a normal function of a healthy habitat, and certain species that survive in native woodlands are adapted to exploit and benefit from these ecological processes.  
At RSPB Abernethy National Nature Reserve in the Cairngorms Connect area, we are mimicking some forms of missing natural processes, in a trial using three 200ha plots of old pine forest. 

In one area, we are introducing grazing cattle to mimic the effect of extinct large herbivores, and in another we are carrying out field-layer cutting to mimic the effect of natural surface fires. Field-layer cutting means cutting the heather, blaeberry, and other ground vegetation, using operating “Robocutter” machines. The third area will remain unmanaged, as a control plot. 

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