Today I attended an informative meeting on Rhodedendron control and habitat restoration and wanted to feedback on some of the interesting points raised.
Background to Rhododendron Ponticum – the most invasive land plant in Scotland.
History of Rhodedendron
European and American plants were introduced by Victorians and hybridized to form a plant that spreads quickly.
Rhododendron ponticum grows fast and quickly out-compete native species. It doesn’t allow light through which inhibits the growth of new saplings or other plant life, affecting the insect life which in turn affects birds and other mammals – reducing overall biodiversity. It also spreads diseases endangering Larch trees and is in danger of wiping a species of lichens that only appear on the West Coast of Scotland.
Rhododendron ponticum poses a huge risk to our already depleted ancient forests and other forested areas.
The Scottish Government has it listed as an invasive species and it’s within its remit to remove it. While funds are being used widely for this, they are targetting areas of temperate rainforest as a priority. Scottish government are releasing a strategic approach to protect the rainforest zone shortly.
How does this relate to Skelmorlie
There is a lot of Rhododendron in Skelmorlie. Kelly Glen has been identified as an ancient woodland and shows signs of being a temperate rainforest but has a huge amount of Rhodendron in it. Kelly Glen is identified as a Site of Scientfic Interest and also suffers from Rhodedendron infestation. It’s all around us, in these particularly sensitive areas and outwith.
Our local habitat is already degrading due to this invasive plant and unfortunately this will accelerate.
We have also seen up at the new forest being created at knock hill, and it will grow faster than the trees can unless there is intervention.
Scottish Rainforest Map
As you can see, we are on the border of what is considered the rainforest zone here in Skelmorlie, and the forests around show indicators that would suggest they could be classified as Temporate Rainforest.
The sheer abundance, diversity and rarity of the species found in Scotland’s rainforest make this unique habitat internationally important. In fact, we have the best remaining sites in all of Europe.
https://savingscotlandsrainforest.org.uk/rainforest
Rhodendron Removal Projects
We heard from two large scale Rhodedendron removal projects well on their way in Scotland.
Torridon Project
In order to increase pubic awareness they embarked on
- Leafletting
- Community Meetings
They experienced that:
- Gardens were found to be a seed source – when people understood the issues, they volunteered to have them removed from their gardens.
- They offered a plant swap – put in some non-invasive rhododendron in place of invasive species,
Use for harvested wood
National trust – project wipeout. Making Biochar from harvested wood.
Rhodedendron clearing at Knoydart
- 35ha dense Rhodendendrons
- 10 years for initial clearance
- Maintenance still happening at 24 years
The technique they used was to cut, burn spray, using glyphosate. Not really recommended now as this leaves a lot of trace weedkiller in the environment and kills more than just the Rhoddies.
They would do stem injection now if they were to restart the project.
Rhoddie Reporting
20 years down the line they have a report a Rhoddie scheme, using a Avenza map. From this could identify heat maps which actually can help locate the seeding bush for removal.
Summary of Rhodedendron Control Methods
Stem treatment – most effective
- Drill into the bush, put a herbicide* in – most effective.
- Stem treatment can be done any time of year and is a once-off treatment
*Soil studies showed after 3 years the residue within the soil after stem treatment was minimal – less than 0.1%
Stump Treatment
- Cut and stack Rhoddie bushes
- Treat stump with herbicide
- Stump treatment requires further site visits to sort out.
Cut Back and Regrowth Removal*
- Cut and stack Rhoddies from base
- Remove as much base as possible
- Visit the site annually to remove regrowth until the stump is starved and degrades
*This is the approach we have taken in Skelmorlie Crescent North.
Removing Rhoddies is not a once-off job whatever you opt for, you must go back and remove any seedlings or regrowth or bits that have been missed.
Advice, Tips and Policy for Ecosystem Restoration and Rhoddie Removal
- Stop the seed source! Get the bushes before they flower.
- Easiest to remove when 6-18″ high – if you see it pull it out! You are stopping a future seed source.
- Deal with small invasions on your own
- If you ensure all the trunk is gone it won’t regrow, you can leave roots in the ground and they won’t regrow from that.
- A mini mattock or hammer is a good tool to use.
Available Funding
For larger areas of Rhodedendron there is available funding.
Funding is available from Scottish Forestry which mainly focuses on the rainforest area. Nature Scot has funding for rhododendron control, again focused on the area of rainforest.
National lottery also available, especially if we can tie in with wider benefit such as education around the woodlands and rainforests in Scotland.
If you have community groups then the quickest thing is just to approach manageable areas yourself.
Joining Community Woodland Association?
https://www.communitywoods.org/join-cwa
Could we join? Something to think about.
Useful Links
An Approach to Prioritising Control of Rhododendron in Scotland
Thanks Naomi for taking the time to put all this useful info on the website. We need to carry on the fight!