COVID-19 (Coronavirus)

Due to the impact of Covid-19 (Coronavirus), the Pembrokeshire Coast National Park Authority has closed its headquarters, visitor attractions (Carew Castle, Castell Henllys and Oriel y Parc), its car parks and sections of the Pembrokeshire Coast Path until further notice. All meetings and events are cancelled until further notice. If you have any queries please call 01646 624800 or email

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Home » Looking After » Conservation Land Management » Invasive non-native species

Invasive non-native species (INNS)

Invasive non-native species (INNS) can outcompete native UK species, physically change ecosystems and damage property. Some, like giant hogweed, can be extremely harmful to human health.

Piecemeal treatment of INNS rarely addresses sources of infection, which implies that treatment will need to continue indefinitely. Treatment is not cheap - the cost of managing INNS has been put at £1.7 billion per year in the UK - so prevention is better than cure.

INNS are drivers of ecosystem change and contribute to the loss of biodiversity and the cost of control if left unchecked is exponential over time, they may also affect human health, cause damage to property and structure and facilitate the spread of disease causing degradation of natural ecosystems.

Volunteers removing Himalayan balsam.
Volunteers removing Himalayan balsam.

INNS in the Pembrokeshire Coast National Park
Find out more about three of the more significant terrestrial invasive plants in the National Park - rhododendron, Japanese knotweed and Himalayan balsam – and the National Park Authority's Stitch in Time project, which aims to to tackle all the three in the Gwaun Valley.

You can also find out more about additional information on legislation, responsibility and the National Park Authority's policy on INNS.

Be Plant Wise and Check Clean Dry information