Bill Shaw – Ecology and Conservation Land Management Adviser
In Britain, Himalayan balsam is a non-native invasive plant species. It is pretty and pink when it flowers, but it is a domineering plant that crowds out smaller native plants, and when it dies back in the winter it leaves sites with bare ground and no stabilising vegetation. This unstable bare ground along river banks where Himalayan balsam likes to grow is a particular problem because it leads to increased sedimentation in a river which detrimentally affects the river habitat.
Fortunately unlike other invasive plant species, Himalayan balsam is not too difficult to tackle and hopefully eradicate before it swamps a site. It can be pulled up in June/July, before it flowers and seeds. However it may take a few years of repeat pulling to actually get rid of the plant at a particular location.
For the sixth year in the row we’re tackling Himalayan balsam along the banks of the River Seph in the west of the National Park. We started at the top of the river catchment gradually edging down as well as going back up stream to repeat the control each year where necessary. The plan is that we eventually eradicate the plant on this river.
It’s proving to be a resilient adversary but the amount of balsam now left on the Seph has been reduced enough for us to also move down onto the River Rye (which the Seph runs into). This season we’re commissioning control work, over a twelve week period, for a stretch of about five kilometres.
The vast majority of the control work will again be done by our three local contractors, who use a combination of strimming and hand pulling to remove this annual plant. Willing bands of National Park Volunteers will also tackle patches including in Duncombe Park National Nature Reserve. A survey conducted by our Volunteers in 2011 along the River Rye from the Seph confluence down to Helmsley has highlighted new areas where balsam is occurring so we know what we’re up against in our new drive against the plant.