Extreme Rhododendron bashing
This week has seen the start of an effort to clear the Cnocan Gorge, Brodick Country Park of Rhododendron ponticum. The Gorge is a spectacular, amazing in that it is just a stones throw from the Castle and in an otherwise unassuming area. We are employing a team, Skye rope Access, to do the work over a two week period. Why Skye? Well, the same team have cleared Corrieshalloch Gorge near Ullapool for the National Trust for Scotland and have proven expertise in this area. Whilst not such a sheer drop as Corrieshalloch, the Gorge is home to a series of waterfalls and pools created in the red sandstone. Carriageways used to take the Duchesses and their entourage up to the bathing pools and to enjoy the scenic splendour. Many of the footpaths follow the original tracks and you can still see the abutments of the original upper bridge.
The guys are working on ropes to cut the stems which are then dragged up to the flat where they are being chipped using a tracked chipper which can access these awkward areas. They are using a capstan winch to haul up the stems and the chipper means that they don’t have to spend lots of time burning the waste. The stumps are then treated either by painting the cut surface with roundup, or by “stem injection” which means drilling a hole and squirting the herbicide in this hole. Two years ago we had a similar team undertaking work in the park’s gorges and the amount of regrowth is fairly small compared to the total cut. Obviously, one cannot go spraying on these steep slopes, so the Skye team with come back for a further two visits to treat any plants that have not been killed. Stem injection and painting of cut surfaces have the added advantage that you are not killing the existing vegetation, what I call “collateral damage”. If there is already vegetation on a site, killing it off can sometime just make a blank canvas for more non-native invasive species to come in. I noticed wild garlic growing under Japanese Knotweed the other day, blanket spraying would just get rid of this also.
Another interesting development in the field of rhodie maceration which we are going to employ this summer is the use of a mulcher attached to a skid-steer which produces small sized chips rather than the shards that the previous mulchers we have employed have made. This means that the follow up control measures are much easier, rather than walking over a leg-breaking collection of branches.
For the last few years, we have employed a small team of rhodie bashers for a few weeks at a time in the winter. They have worked through areas, taking out rhodies that are growing in amongst the birch and other regenerating trees as well as attacking “virgin” growth. Most of the “weeding” is done with loppers and bow saw, but on larger stems chainsaws are used. We burn the branches where they is lots of waste, but just stack the stems where space is limited or the rhodies are scattered. It is great firewood, so we save what we can, and we also have a kiln to make the rest into charcoal.By recording how much rhodie we have cut each day, we have a good idea of how much it costs to get rid of it. It can range from around £500 an acre for scattered stems, to £1200 an acre for wall to wall rhodies. It shows that prevention is better than cure, that is stop the rhodies getting out of control in the first place! Unfortunately for us, no-one thought of them as a problem for the first 100 years of their existence in the UK. If you look at the areas above Whiting bay, Corriegills and Lochranza on Arran and you can see the £ signs! The damage that invasives do is not just ecological it is economic with the cost of removal exceeding the value of the land in many instances, with hill land fetching only a few hundred pounds an acre. No one has yet costed how much it would be to remove rhodies from the whole of Arran, but what will it cost in 20, 50 or 100 years time?
If you want to see the mulcher in action have a look at
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