Invasion Biology

This is a topic that people far cleverer than me should be commenting on. However, given that I have been dealing with invasive species for a little over twenty years now – I do believe that I have something to bring to the table.

Perhaps we should be looking more at the general publics ‘perception’ of Japanese knotweed rather than the actual ‘invasion biology’ graph?

Invasion biology is all about establishment/growth phase/lag phase of invasive non-native species – this can take hundreds and thousands of years.

In contrast, the general public’s perception of a perceived problem can change overnight. All it can take is a news headline or an article in a tabloid and suddenly everyone’s talking about a certain issue that only the day before – they knew nothing about.

So …what is it about Japanese knotweed that has caught the public’s attention?

Well…let’s be honest – a lot of it has to do with money. If you have a problem plant – that will stop development dead in its tracks – then people are going to sit up and take notice. If you have a plant that can single handedly prevent houses being built – when there is a huge housing shortage – then people are going to wonder what’s going on.

This is what we have with Japanese knotweed.

At the time when knotweed first raised its ugly head – we had a situation where developers were on a financial wave – borrowing huge sums of money and knowing that they would get a good return on their investment. We often had situations where the developer would borrow several millions of pounds based on having 100 houses built in 12 months’ time – the repayments on the borrowed funds were often deferred until the sales started to come in…

So what happens if – after borrowing 5 million – you are told …’sorry you cannot build until the Japanese knotweed has been eradicated – and that will take three to five years of repeat herbicide application?’

More recently we have had mortgages being turned down and neighbour disputes over invasive species spreading over land boundaries. This is a relatively new problem and one that people have been unaware of …

Hence the horror stories in the newspapers and the TV shows, showing wrecked houses and tearful home owners.

It makes good TV and great headlines…..

The downside of the whole public perception angle is that it can pale, wane and disappear with ‘overkill’…have the public been ‘over-knotweeded’…??

There are respected environmentalists and writers who believe that plants such as Japanese knotweed are not the problem species that we have been lead to believe. They believe that nature has one grand master plan going on – of which we (the human race) are only a minor blip. They believe that these aggressive invaders are actually protecting our bare earth from the ravages of erosion and run off – and are simply growing where our native species cannot survive??

Maybe global warming and longer term environmental changes will see the worlds bio-diversity change, maybe we will see certain species becoming dominant where previously they were simply only ‘invasive’…?

Currently, the agreed UK strategy is to manage and eradicate problem species where they are deemed to be growing either over enthusiastically or interfering with development. Much of this legislation has been led by European initiative…perhaps the BREXIT situation will lead to changes in how we approach these species.

Much of my work has been very ‘black and white’ with Japanese knotweed being removed from areas of new housing. If left, the plant would cause misery to the home owners, so removal is a fairly obvious answer. Maybe as we gradually defeat the aggressive invader the sites that we treat will be more complex, perhaps with situations where eradication and removal are not beneficial to development or the environment? It is perhaps at this point that somebody needs to be thinking ….is this really necessary?

Whilst knotweed is high in people’s perception then works will be done to eradicate the plant. But, if interest wanes or these plants become accepted as part of the ‘norm’ – then our typical native species will take a battering.

Who is right?

Watch this space to follow the discussion.

Mike C