“If a pet day arrives in winter, shall I bask in the stillness and warmth and the sun’s enamelling with the same, almost pagan, gratitude, or shall I feel ‘well that’s fine, but it isn’t nature?’”

– Nature Undone and the End of Love, Michael Viney

The Convention on Biological Diversity described invasive alien species as “direct drivers of biodiversity loss across the globe”. Unusually for issues around ecology, and flora in particular, invasive species stand out as a topic that makes it into mainstream news with relative regularity. It’s also often misunderstood, because there are a lot of similar terms that cause confusion.

Two umbrella terms that are used interchangeably are “non-native species” and “introduced species”. This covers any animal, plant, fungus, or micro-organism that is introduced to an eco-system because of human action rather than the natural expansion of its range.

That definition is widely accepted and isn’t really debated beyond when a bunch of ecologists are in the pub after a conference and someone says “well before that last glacial maximum” just to cause trouble. For this podcast and all useful purposes, that’s the definition we’re working from.

However, where people sometimes get tripped up is that not all introduced species are particular points of concern. Some introduced species don’t cause significant harm and so aren’t a priority even if best practise is to limit them, or not to encourage more. In the Irish context, hedgehogs are an introduced species, brought to the island by the Normans who bred them to eat. They quickly naturalised to the Irish landscape, which was very similar to their native habitats, and there is no credible move to call for their removal. Most people don’t even know that hedgehogs aren’t a native species. This is different from invasive alien species.

The term naturalised is sometimes conflated with non-harmful, but all it means is any introduced species that can survive and reproduce without human intervention. There are plenty of garden plants or abandoned pets that might make their way to freedom, but are unlikely to survive long enough or reproduce and so they don’t enter the conversation. So while not all naturalised introduced species are invasive alien species, all invasive alien species must be naturalised.

IAS or invasive alien species is the official, technical term used by most ecological or scientific groups to describe the kinds of introduced species which spread and cause harm to the eco-system that they’ve been introduced to.

In biological terms, the word invasive refers to how quickly something spreads not whether or not it was introduced. Its most commonly used in botany, to describe the growing patterns of plants like bracken or gorse. These are native species that are normal parts of their eco-system but without competition both plants spread extremely fast. It’s the alien part of invasive alien species that defines them as introduced but it’s frequently dropped from speech outside of official documents.

Invasive is one example of terms that come up in ecological conversations that have very different meanings in other contexts. For example, the colonisation of plants following fire or grazing should not be conflated to its human socio-political meaning. Similarly the term native for native species can be conflated to ethno-nationalist rhetoric in a disingenuous way, not only because it ignores the different definition of words but also that ethnicities are not comparable to species in any real terms. There have been conversations around using invasive introduced species instead of alien, because of the human connotations of the word. While personally I do tend to use “introduced” species instead of non-native, I do it because I think the meaning is just clearer to whoever I’m speaking to regardless of their background knowledge. I have never once met someone who conflated botanical terminology to human migration in anything close to good faith. In fact, a safe rule of thumb for when in doubt is to just assume anyone who tries has no idea what they’re talking about.

In Ireland the most famous and commonly discussed invasive species are rhododendrons.

Rhododendron is a group of flowering shrubs with a wide range across Asia and eastern Europe. In the Irish context we are usually talking about rhododendron ponticum specifically as our problem species. Rhododendron ponticum was primarily planted in ornamental gardens, originally in the landlord estates who could afford to have them imported as a status symbol. You can refer back to some of the conversation in episode two about the effects of colonialisation on the Irish landscape for where that fits in.

Despite a whole host of laws, policies and press releases about rhododendrons in Ireland and their harm, they are still for sale in nearly every garden centre in the country as a garden plant.

The legal and policy situation for invasive species is a lot more robust than the action that’s been taken so far. We have international, EU level and national legislation in place that identifies invasive species as a priority. Target 9 of the Convention on Biological Diversity (CBD) calls for controlling or eradicating IASs. There are similar goals set out in the EU Biodiversity Strategy in Articles 15 and 16 which led specifically to the binding EU resolution 1143/2014 Regulation on the prevention and management of the introduction and spread of invasive alien species. On top of that there are sections of other EU laws and projects, the Natura 2000 network, the LIFE programme, and species specific regulations that cover this area.

On the national level, this falls where it usually does in these conversations to the National Park and Wildlife Service and the various local councils. The last episode, number 6, covered some of the details of that. Most recently the 4^th National Biodiversity Action Plan 2023-2030 set the goal to reduce alien species spread by at least 50% by having the NPWS establish an IAS unit. Funding and statutory powers for such a unit has yet to be published.

All this comes under the category of biosecurity. Biosecurity is a blanket term used to describe measures taken to prevent the introduction or spread of harmful organisms, pests or diseases into a given region. This includes agricultural pests, invasive animal or plant species, and viruses such as Foot and Mouth Disease. While the word is most commonly used to refer to plant and animal health, human health is also included. Failures in biosecurity has led to the spread of a number of diseases effecting forestry, most famously in recent years Ash Dieback.

Ash dieback is a fungal infection that first arrived in Ireland 2012 on tree imports from continental Europe. In the past nine years it has spread across the island and is predicted to lead to the death of most Irish ash trees within the next two decades according to Teagasc, the Irish Agriculture and Food Development Authority.

Just in 2020, young oaks imported for landscaping in a housing development in south Dublin introduced a potential devasting pest, the oak processionary moth. If it had spread, it could have had a major impact on oak populations in Ireland, comparable to ash dieback. As part of the job I had at the time I was in touch with the department to get confirmation on how sure they were they’d eradicated the whole infestation. I was basically told that they had no intention of liaising with the public or outside on that subject at all or releasing any detailed information.

Two years later the incident was included in the mid-term report on the Biosecurity strategy as follows: “In June 2020, there was a finding of the harmful organism Oak Processionary Moth at a public park in Dublin by a member of the public. Ireland has a Protected Zone status for this Moth. Further investigations revealed that this tree was imported from another EU Member State and was planted in the Spring of 2020. The nest was removed within 6 hours, and formally identified by the lab. All Oak trees from the imported batch were destroyed. An intensive survey was carried out in the surrounding area and there were no other findings. New import regulations in relation to import of Oak were introduced – requirements for certain height, certain width, free from OPM.”

I don’t have any issues with this. Swift action was taken and it seems like it was handled well, but given that this action was only possible because of a report from a member of the public, why keep the reaction so quiet? Invasive species is something that requires transparency and communication with the public to monitor.

I’ll link to the Plant Health and Biosecurity Strategy in the episodes sources like always, but all in all it’s a good comprehensive document. I don’t have major criticisms of the strategy but rather the lack of public discussion its given and whether the momentum exists to implement it.

One of the main ideas in the strategy outside of better monitoring of imports, is the establishment of a Pest Risk Analysis Unit, to deal with cases like the moth infestation I just described. Again, there’s nothing wrong with this, but what is the reason for establishing this pest unit within the Department of Ag at the time as the Invasive Species unit within the NPWS?

It’s a pity there isn’t a more informed public conversation on this subject because it’s one of the issues where environmentalists and the agricultural sector are most in alignment. The Irish Famers Association have been involved in some campaigns to improve matters on animal health and biosecurity, responding to outbreaks of bird flu or African Swine Flu, on the national and EU level but they haven’t been among their better publicised campaigns.

There is so much potential is this area for collaboration that hasn’t been tapped into yet.

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Episode 7 Sources

Department of Agriculture, Food and the Marine (2020) Plant Health & Biosecurity Strategy 2020-2025

Department of Agriculture, Food and the Marine (2022) Plant Health & Biosecurity Strategy 2020-2025 Mid-Term Report December 2022

EU Overview on Invasive Alien Species

Halpin, Danny (4 September 2023) Invasive alien species ‘travelling around the world at unprecedented rates’ The Irish Examiner

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