As we head towards Invasive Species Week, organised for later this month by the GB Non-Native Species Secretariat (GB NNSS), I thought it would be timely to consider the wider picture on invasive non-native plants in the UK.

When it comes to surveying, some may not appreciate that there are rather a lot more than the ‘big three’ of Japanese knotweed, Giant hogweed and Himalayan balsam – another 74 species of plant have legal status as invasive non-native species (INNS) under various Acts!

So how many species are there?

Well, the numbers go something like this:

• 77 separate entries in our INNS plant species list covering UK and European legislation
• 17 of these are aquatic species
• The Genus Cotoneaster has 5 species alone – Fallopia 3, Rhododendron 3, Ludwigia 3, Heracleum 3: 2 each for Allium, Elodea, Myriophyllum, Parthenocissus and Polygonum.

So, if my maths is correct we have 50 different plant Genus groupings which are either Scheduled under the Wildlife & Countryside Act or WANE or, they are ‘Species of Concern’ under EU Invasive Alien Species Regulations. Of this last group, 8 species are specifically listed as subject to Management Measures in England & Wales under The Invasive Alien Species (Enforcement and Permitting) Order 2019. Whew!

The ‘big three’ invasive plants are just part of a bigger picture

There is a point to all this; that the ‘big three’ are just a small part of the bigger picture. OK, some of these plants are a bit niche – literally – and may only be found (outside of gardens) in very specific habitats e.g. coastal sand dunes or montane terrain/cliff tops. But this doesn’t mean these plants are any less invasive from an ecological point-of-view (displacing native plant communities), only that they are ‘specialists’ in terms of sites where they can colonise successfully.

Not wishing to labour the point too much but the fact that they are specialists can cause greater concern environmentally speaking than, say, Japanese knotweed, because the habitats they invade are themselves unique..…

Let’s keep these forgotten plants in our minds

So, a simple message/request from me this week is “let’s all try to keep these sometimes forgotten plants in our minds during site surveys”. In many cases, PCA members may have been asked to only survey/report on Japanese knotweed because of its potential to impact on property value etc. However the more INNS species you can recognise and report on, the better the advice you can give your client regarding their wider obligations under the above Acts/Regulations – and to prevent spread to the wild.

Some surveyors may not wish to open themselves up to the wider liabilities of a broad species sweep of the site. But as long as worded carefully, by adding a simple statement that “although not part of the client’s original instruction, you have a Duty of Care to mention ’x’ ‘y’ or ‘z’ species seen during the course of the survey”, you will have fulfilled your wider professional duties and contributed to the overall drive to ‘Stop the Spread’ (a term coined by the GB NNSS although mainly in relation to aquatic species).

This is no small thing as PCA member surveyors probably visit 100’s of sites a week, 50 weeks a year. More big numbers. Which means we can make a significant contribution to the Government’s call for greater public awareness (Commons Environmental Audit Committee report).

Spread the message about invasive non-native species

We encourage all our members to get involved in spreading important messages about invasive non-native species:

• They are a problem ecologically and economically
• We all have a collective duty/need to prevent them establishing and spreading
• Professional management solutions are available once the identity and scope of a non-native plant has been established

How can you improve your invasive plant identification skills?

If you are feeling inspired and want to improve or enhance your botanical skills (identification) there are plenty of opportunities to do so. Indeed the first Invasive Plant Identification courses for this year is coming up very soon on 13th May 2021!

In the meantime, you can grab a copy of our Practical Management of non-native plants in the UK and Ireland. This guide really does take the ‘guess work’ out of planning and executing effective management of most of the above species and a few others besides (e.g. bamboo, buddleia).

Get involved during Invasive Species Week

We will be sharing two presentations on Aquatics and Umbellifers during ‘Invasive Species week’ (24-30 May 2021). Both of these ‘fit in’ with themes the NNSS are covering on those days so please put the dates in your diaries and think about how you and/or your businesses may want to ‘get involved’. More information will be shared in the lead up, so keep an eye out!

Our regular monthly webinar on Thursday 27th May will have an invasive species focus too. “How invasive weeds can impact the urban environment” will be presented by PCA Trainer Jim Glaister. A different focus thinking about those traits which make Japanese knotweed, for example, so troublesome (and so widespread!), why there are plenty of reasons to think the above list should be expanded to 78 or even 79 fairly soon, and how one of our most ancient native plants sometimes needs to be ‘managed’ too!

To find out more and to register, simply click on the button below.

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