Invasive Species (Clematis) Removal, Saltfleetby-Theddlethorpe NNR, 2021
Case Study Type:
Habitat Management Case Study
Sand dune system:
Saltfleetby-Theddlethorpe NNR, Lincolnshire
Case Study Subject:
Removal of clematis, invasive species which had smothered the dunes and trees, and dead sea buckthorn on the NNR by cutting and burning, to allow recolonization of dune grassland. Work completed by Natural England.
About The Dune System Habitat Management Intervention
Site Background Information:
The site is densely vegetated and the area intended for clematis removal is impenetrable.
Invasive clematis, which reached the dunes at Saltfleetby-Theddlethorpe NNR by escaping from gardens, has been rapidly colonising the dunes on the reserve and killing native scrub. It’s a fast-growing climbing plant, which has even overtaken mature hawthorns and elders, as well as large areas of sea buckthorn – a protected species on the reserve.
What was the issue/change you hoped to make?
The clematis needed removing from the site, as well as the areas of dead sea buckthorn underneath to restore the dune grassland, and make way for dune grassland species to recolonise the exposed ground. The intervention also needed ensure that clematis wouldn’t regrow following removal, as it is prone to do.
What was the suggested intervention?
To use mechanical cutting, burning and burial on site to remove areas of clematis and dead sea buckthorn, and prevent clematis regrowth.
What did you do?
Areas of dense clematis were identified. Clematis was cut using machinery and the removed biomass was burned on site, and then buried once cool. This technique was employed to minimise the chance of clematis regrowth from removed biomass. A buffer zone of habitat was left unexcavated between the clematis dune area and the adjacent salt marsh on the reserve.
How did you do it?
LiDAR data and site visits were used to identify areas for clematis removal.
Contractors were brought in to cut areas of clematis and dead sea buckthorn using machinery, and then to burn the removed biomass in controlled fires on site. Burned material was then buried on site when cool. Work areas were divided into sections and fire breaks were employed.
The reserve team were aware that there was badger in the area so an ecological clerk of works (ECoW) was required prior to works.
Equipment used: Komatzu 360 excavator, JCB Agri-special telescopic handler with heavy duty grab, fuel bowser plus Kubota for transporting the fuel.
How was the site / intervention monitored?
Natural England reserve wardens visited the area 3-4 times a week whilst the contractors were operating.
Photographs were collected, including aerial imagery, at the beginning and end of the works to monitor and record the changes made.
What modifications, if any, did you make to your initial plan and why?
About a quarter of the way through the planned works, a modification was made to the work footprint of the job area. The LiDAR information used to inform the original work plan only gave us so much information, and a better assessment of the site was made on the ground as the commencing works better exposed the situation. The experience of the contractors combined with multiple site visits made problem solving and adapting the plan smooth.
How much did the intervention cost?
What else went well?
In removing the clematis, several unexpected dune slack pools were exposed, so the machinery on site was also used to excavate these further – widening shallow slopes to open up an additional habitat for wildlife in the works area. These pools would have previously been difficult to access by much of the wildlife, including dragonflies which breed in slack pools, that live on the reserve.
The contractors also buried and covered the burned biomass so well that reserve staff needed to consult the coordinates during a site visit to identify the burial area.
By planning a series of site visits in preparation before works and by reserve staff visiting regularly while contractors were on site, a good working relationship was built leading to smooth management and problem solving.
How were the public and others engaged?
Natural England reserve wardens visited the area 3-4 times a week while the contractors were operating on site, to answer any queries that the public may have and explained the value of the work for the reserve wildlife.
Posters were created and displayed on site before and during the works period so that regular reserve visitors expected to see contractors on site, and could find out both what was happening and why this intervention was important for the health of the reserve.
A blog post was published on the Dynamic Dunescapes website to explain the issues that clematis presented on the reserve, and why its removal was an important task. https://dynamicdunescapes.co.uk/2021/03/removing-invasive-clematis-lincolnshire/ This blog and additional images were shared on Dynamic Dunescapes’ social media channels.
How were communities or volunteers involved?
Messages were shared using the reserve’s Natural England volunteer newsletter. The area will need management in the coming months/years to prevent regrowth and allow colonization of the newly-exposed area with dune grassland species, which reserve volunteers will be involved in.
Is the intervention working?
Please describe how. What has changed?
Arial images show the extent of the clematis removal, but the site will need monitoring over coming months and years to treat regrowth and deal with additional clematis in the dune grassland and dune woodland beyond the target area for this removal.
It’s not gone for good yet, though, and additional maintenance is needed to prevent regrowth from roots left in the soil. After 2 / 3 months, vegetation began to grow back in the bare sandy spaces exposed. The original contract focussed on removing dead sea buckthorn smothered by clematis, so there are some areas of clematis in the grassy areas left untouched by the original contract. We’re choosing to use DOXSTAR PRO or PAS TOR for the clematis, rather than glyphosate on three hectares to not disturb the grass species also in the area, and then trial one hectare with glyphosate, which is more effective at killing clematis roots but has a wider impact on other species.