Wednesday, 12 August 2009

I think were turning Japanese, or is it Himalayan...American?

Continuing my theme of invasive plants the next on our list of most Britians most un-wanted is Japanese Knotweed. Now if you think Balsam is bad Knotweed is the stuff of nightmares.

In Japan, Japanese Knotweed is controlled naturally by a combination of fungus and insects. However, in the UK, there are no natural enemies for Japanese Knotweed and it out competes all our native species for light, water and nutrients.
The speed at which Japanese Knotweed has spread throughout Britain has been nothing less than spectacular. The damage it has already caused to commercial and domestic sites is practically unquantifiable and it now occupies a site in every 10km_ of England and Wales and is also present to a lesser extent in Scotland, Ireland and other parts of Europe.
The aggressive growth pattern is capable of exposing weaknesses in hard engineered structures such as concrete, tarmac, brick walls and foundations.

Specific problems caused by Japanese Knotweed are:

Damage to paving and tarmac areas
Damage to retaining wall structures
Damage to building foundations
Damage to flood defence structures
Damage to archaeological sites
Reduction in land values
Aesthetic issues
Reduction in biodiversity through out-shading native vegetation
Many insects / wildlife that are dependent on our native plants are lost or in danger
Restriction of access to riverbanks for anglers, bank inspection and amenity use

And it's here. We know that it is present in the Eamont system but have scant information on it's distribution throughout the rest of the catchment.

Between the two of them Balsam and Japanese Knotweed represent a serious threat to the ecology of the Eden system. When all of this is coupled with threat from other invaders such as signal crayfish and the salmon parasite Gyrodactylus Salaris (GS) things can look pretty bleak.

However in Eden apart from extensive distribution of balsam, we have managed to avoid being colonised by the others. This has been due to a combination of awareness raising and a huge slice of luck.

We must raise our game to not only control the rate that non-native species are having in the catchment but mount a extensive awareness raising campaign. Sources of introductions can be numerous from 'well meaning' individuals who think they look pretty through to commercial sources such as garden centres. There are lots of other species to be aware of. I've just heard of problems being caused by 'Skunk Cabbage'...the mind boggles as to what that looks / smells like?

We should strive to ensure the Eden retains as many of it's native species as short we need to repel these alien invaders...before it's too late!

The 'striking' advert is from a company called Japanese Knotweed Solutions (JKS) who's Director Mike Clough is helping ERT to scope a project map the distribution and produce a strategy on the Eamont and Petteril sub-catchments. Mike and JKS are donating a significant amount of time to support our charitable activities. They are also corporate sponsors of the Wild Trout Trust. Visit their very informative website