The costly battle against invasive species – A growing challenge for Irish councils

The Journal Investigates recently reported that local councils spent more than €8.5 million over four years combating invasive plants that threaten ecosystems, properties, and public health
16 January 2025
The fight against invasive plant species in Ireland is an expensive and seemingly endless battle.
Local councils have spent over €8.5 million between July 2020 and August 2024 attempting to control these environmental threats, The Journal Investigates revealed.
Yet, experts like Eoghan Daltun, a rewilding advocate, suggest this figure is only a fraction of what’s needed to tackle the issue effectively.
Scale of the problem
Invasive species, such as Japanese knotweed, giant hogweed, and rhododendron, wreak havoc on native ecosystems.
These species outcompete indigenous plants, damage property, and even pose risks to human health.
For example, giant hogweed sap can cause severe burns, while knotweed’s persistence makes it notorious for growing through concrete.
Local authorities have primarily focused on herbicide spraying of knotweed species, which accounts for much of the expenditure.
As part of its ongoing multi-part series, The Journal Investigates obtained detailed spending figures through Access to Information on the Environment (AIE) requests for its SOIL INVADERS investigation.
The findings revealed that Mayo, Cork, and Meath county councils were the top three spenders, allocating approximately €1.28 million, €950,000, and €814,000, respectively, over the four-year period.
Galway and Fingal County Councils followed closely, spending around €700,000 and €650,000 each.
However, this effort only scratches the surface, as some councils could not provide complete data, and funding gaps hinder progress.
Financial and environmental costs
Despite millions being spent, the spread of invasive plants continues.
The Journal Investigates highlighted that some councils have struggled to utilise available funding effectively, leaving over €1.2 million unclaimed between 2020 and 2024.
Most resources come from grants such as the Local Biodiversity Action Fund and Transport Infrastructure Ireland (TII), but local authorities often dip into their internal funds to cover shortfalls.
Spending on invasive species management is typically higher in the west of Ireland, where favorable conditions allow rapid proliferation. In areas like West Cork’s Beara Peninsula, invasive plants and animals pose “huge problems,” according to Daltun.
Steps forward
Efforts to combat invasive species are gaining traction at the national level.
The Journal Investigates reported that the new Invasive Species Unit, launched under the National Biodiversity Data Centre, aims to improve coordination and early detection.
This unit also manages initiatives like the Shared Ireland Biosecurity and Invasive Species Initiative, which spans both Ireland and Northern Ireland.
While the cost of inaction is severe, a more proactive and coordinated strategy could yield long-term benefits.
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