|Himalayan balsam 2009 (4 hours to clear) on the right in 2010 took 30 minutes to clear.|
I got into an interesting discussion with a couple of people who think this plant should be left alone and in 30 years it will die away leaving new opportunities for other plants. They also suggest that they are better suited to our changing climate. I strongly disagree with their ideas as a catastrophic loss of plant biodiversity would be lost in the process. From 2009, Himalayan balsam has encroached into every habitat on our Local Nature Reserve. All these habitats would be stripped of ground flora which would be replaced by a mono-culture. Mono-cultures are very risky things. go ask a forestry professional about the impacts of covering so much of the UK in larch in hindsight of the recent devastating disease. Resilience to change comes through diversity. You may get lucky by putting all your chips on Himalayan balsam on the Earth roulette, but I think it is better to spread the risk across almost all flora.
There are some great efforts to try and tackle this plant across the UK, but unless a more holistic approach is taken, you will never get rid of this plant. Realistically, this means starting at the head of water courses and working your way down. The photo above, did not remove Himalayan balsam forever, we've been picking this patch each year since 2010. In recent years, we have been going upstream of the Nature Reserve and tackling it there. This needs to happen everywhere in a coordinated way if there is any chance of success and to avoid wasted efforts of the past. For a larger watercourse, say the Taff, this means starting in Brecon and systematically moving your way down, or getting an awful lot of people to tackle it in a coordinated fashion. Will that work alone as a one off event? No. Himalayan balsam germinates as early as April and last year I found some in November. This means going back over the same sites over a full season of growth.
That leads to an important question of how many seasons would you need to do this for?
In 2013, thanks to a Welsh Government-funded Tidy Towns project awarded to Torfaen County Borough Council on the back of our volunteering work, large new areas of Henllys Local Nature Reserve became accessible. On top of this we were also getting some of the other areas where Himalayan was already being treated more under control. In one new patch in 2014, we found an area which was completely dominated by Himalayan balsam. You couldn't see more than 30 cm into this area. We tackled this and removed all of the balsam. In both 2015 and 2016, there was no visible difference to the density and abundance of Himalayan balsam before we again removed all of it. In 2017, however, the density was hugely reduced.
From this we think it takes 3 years to see a significant decrease in the seed bank. Seeds have a natural viability in the soil and after that they will rot. I imagine that work in this area needs to be followed up for the next 2 years. So 5 years of work altogether. So to do this on a larger scale would need an enormous resource of funding for 5 years to deliver.
The table below shows the effort our group has put into (and adjacent to) the LNR to clear Himalayan balsam over the last 4 seasons. We still have around 10 hours to clear what is left on the LNR in 2017, but we tackled the same area which we did in 2016. This backs up what we have been seeing this year.
|Year||Vol. Hours||No. of events|
If we started in 2009, how come we are still spending so much time on it in 2017? Early on, we didn't get to tackle the whole Local Nature Reserve and that was before we considered the possibility of seeding of our cleared areas from upstream. This will also be true of any other watercourse. I have seen tributary banks rammed full of Himalayan balsam, a Welsh Water sewage treatment plant in Cilfynydd totally overgrown with Himalayan balsam. I imagine lots of feeder streams are also in privately owned land and all of it needs to be sorted out in order to properly tackle this plant.
The costs do to this properly would be enormous. I can see why many people put their head into the sand (or soil) and say they can't/wont deal with it, and by general inaction by authorities the situation is going to get much worse. For us, I'm very pleased we haven't had our head in the sand and continue to be so proactive and make those inroads.
One thing is for sure, it'll be very interesting to revisit and comment on this article in 8 years time.