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14 May 2024

Securing our natural heritage: investment and innovation

Written by Rob Dewar, INNS Operations Manager
Three rangers, dressed in full waterproof clothing and wearing heavy-duty gloves, hold stem injection drills in a Charlie's Angels style pose! Tall rhododendrons grow behind them.
Brodick’s ‘rhodie-busting’ team of rangers
We are taking a multi-dimensional approach in dealing with one of our most difficult land management tasks: controlling invasive non-native species (INNS). We are investing in people, working with specialists, and leading the way by sharing our knowledge.

The removal of invasive non-native species is being carried out by a combination of a National Trust for Scotland ‘green team’ and specialist contractors.

As the Highlands and Islands INNS Operations Manager for the Trust, I have spent many years dealing with invasive species on Trust land. INNS removal is just one aspect of habitat restoration work, but in my experience it is the first stage – and the key conservation priority when our native habitats have been ecologically damaged by invasive plants. Controlling INNS on a ‘landscape scale’ requires a multi-dimensional strategic approach, which must be sustained for many years if it is to succeed. At the Trust, we are finally seeing the success of this approach and are witnessing the ‘end game’ at many of the places in our care.

A close-up of some violet-blue bluebells growing in a woodland.
Our INNS rangers are protecting native habitats and biodiversity.

Project Wipeout has seen the removal of Rhododendron ponticum on a landscape scale at properties such as Brodick Country Park on the Isle of Arran. Brodick was the first to develop a Trust team specifically to tackle INNS, and they have been using the method of ‘stem treatment’ in which the Trust has been a leading exponent.

Brodick ranger Jake Dove explains: ‘Stem treatment is targeted and uses less herbicide than spraying – eliminating damage to non-target species as a result. It also negates the effects of burning tonnes of cut rhododendron and the associated carbon release. Instead, the dead rhododendron decays naturally over a period of a decade or more, providing excellent standing and fallen deadwood habitat. In addition, stem treatment avoids the particularly unpleasant result, most prevalent after flailing, of regrowth from a stump growing back as a fine, multi-stemmed, dense plant. This proves much harder to treat than thick-stemmed mature rhododendron that has never been treated before.’

“We have employed an in-house team of three INNS rangers over the winter. These ‘rhodie-busters’ have been out in the woods almost every day (weather permitting) and have been diligently stem injecting rhododendron all winter long.”
Jake Dove

Jake continues: ‘We think this project has been incredibly successful in more ways than one. Firstly, we are offering opportunities, qualifications and further experience throughout the winter months for summer seasonal rangers to stay on with the Trust, in the hope that full-time ranger roles will be achievable sooner. Secondly, having an in-house team negates the expense and frustrations of having paid contractors come to Arran only to spend hours or days grounded due to poor weather conditions or other logistical challenges. And finally, it cannot be understated how useful it is to have the INNS rangers on hand to carry out alternative tasks when they cannot be in the woods stem-injecting due to poor weather.’

The case study at Brodick has paved the way for investing in people, by efficiently utilising seasonal rangers and developing their skills. In the Highlands and Islands, we have followed this formula by offering contract extensions to two INNS rangers. The contribution to community engagement has also been invaluable, with newsletters and an increase in meetings helping people feel closer to the project. Contractors still play a key role – particularly specialist rope access workers that reach INNS in our dramatic gorges – but upskilling National Trust for Scotland staff to work with them is a winning combination. The local knowledge and continuity of our own dedicated staff tackling INNS has reaped benefits and is part of our overall strategic approach to successfully restoring native habitats.

Through Project Wipeout, which was funded by players of People’s Postcode Lottery (PPL) and NatureScot, the Trust has created an infographic incorporating case study work to show the overall strategic approach we have applied to INNS control. We have shared our knowledge at the GB INNS Secretariat and NatureScot conferences. The Alliance for Scotland’s Rainforest (ASR) is a big supporter of the Trust’s contribution to protecting one of our most distinct and important woodland habitats. We have contributed resources around the use of stem treatment that are available on the ASR website.

A large infographic detailing the various methods used to control invasive non-native species.
Nature restoration and protection through INNS control infographic

I was recently asked to explain why INNS control was important and what would the situation be had we not invested in this work. It is a good question! To answer that, I offered the example of Corrieshalloch Gorge.

Without our investment in INNS control work, the edges of the gorge would be choked with Rhododendron ponticum, blocking some of the spectacular views into the depths of the gorge. Heavy shading exotic trees such as western hemlock and rhododendron would block sunlight that is crucial to life and biodiversity. Invasive Gaultheria would become rampant as a suppressing understorey plant. Many rare lichens would be lost; ancient woodland plants would eventually disappear such as primrose, bluebells, wood anemone, violets – and with this, the associated insects that depend on them. The next generation of broadleaf saplings – hazel, oak, birch and rowan – would dwindle, jeopardising the future of this SSSI-designated woodland as it would fail its ecological favourability assessment. In time, the light and leafy Highland woodland would become a dark green jungle – a ‘new normal’ that we are not prepared to see happen.

If you visit Corrieshalloch Gorge today, you will struggle to find a non-native invasive species, with only a few stragglers remaining. When there is no sign of INNS, our work to protect Scotland’s habitats and our properties has been a success. The irony is that the massive effort taken to achieve this will have ‘been and gone’ without trace. I’m fine with that, knowing that the exponential cost of control work has been halted; the natural heritage has been protected; and our native habitats can thrive with their future secured.

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