Himalayan Balsam flowers
Jan 16 2018

Clearing the murky waters of invasive species

In the UK, millions of pounds and thousands of hours are spent each year tackling the major issue of invasive non-native species. But not all non-native species are invasive and not all invasive species are non-native – confused?

Earlier this year a new scientific study from the University of York was released. Media reports said ‘non-native plants are not a threat to our native ones’. While this may be true for the majority, the resulting headlines and articles helped cloud the already murky issue of invasive non-native species (INNS).

While, as the study suggested, many non-native species are generally localised and still allow native flora to be abundant, this is not the case for all. The serious negative impacts some species cause should not be underestimated or glossed over.

For example, in Australia in the 1980s, the rubber vine weed that was smothering over 40,000km2 (twice the size of Wales) was not particularly localised or allowing native flora to be abundant. If left unchecked it could have been far more destructive and widespread.

But previously invaded areas are now recovering thanks to the energy and resources committed to tackling the problem, and the identification of an effective biocontrol agent.

The issue of non-native and invasive species needs to be separated and clarified.

Invasive non-native species are a serious threat

Along with climate change and habitat destruction, invasive non-native species are classed as one of the biggest threats to biodiversity. But there is much less awareness around the issue of INNS: what they are, the problem they cause, what the public can do, etc.

There are currently around 2,000 non-native species in Great Britain (as part of the same island, Northern Ireland usually works with Ireland on matters of INNS). Of these, 75% are plants, 22% are invertebrates and 3 per cent are mammals and others. Only 10-15% of these are invasive. But these invasive non-native species have serious negative impacts on native wildlife, natural processes such as water management, human health and the economy.

Himalayan balsam occupies over 13% of the UK’s rivers and the Environment Agency estimates it would cost £300 million to eradicate it. This damaging, albeit beautiful, plant out-competes native flora to dominate large areas. It also dies back in winter reducing shelter for animals and leaving the ground bare, which reduces bank stability and increases the risk of soil erosion, while dead plant material can enter watercourses and contribute to flooding.

The many land managers, volunteers, NGOs, etc. working on INNS understand that not all non-native species are (currently) a problem, and would not wish to vilify every non-native found in the UK. But trade, through horticulture and exotic pets, is a major route for INNS entering the country.

Therefore, we need everyone to be aware of the INNS issue, the species involved and the vital role we can all play to stop them.

Actions for all

What can you, me and all of us do? Well, we can simply…

Buy right: find out what invasive non-native species are out there (see link below) and actively choose not to buy them for our gardens, ponds, etc. – there are many alternatives.

Be responsible: make sure we do not allow INNS to get into the wild – disposing of green waste responsibly, preventing animal escapes, removing INNS if possible, etc.

Tell others: raise awareness by speaking to others about the problem and advising them to buy right and be responsible too.

Watch out: there are a few high alert species (see link below) that we need everyone to keep their eyes out for to prevent them getting a foothold in the country, like the Asian hornet that can decimate native bee populations.

Find out more

Read our Wood Wise on INNS and discover what the Woodland Trust and others are doing
Find out what INNS are in the UK and how to identify them
Discover which species we all need to be vigilant for

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