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Japanese knotweed survey

Invasive Plants

An invasive non-native species is any animal or plant that has been introduced artificially by people, and has the ability to spread, causing damage to the environment, the economy, our health and the way we live. It is estimated that invasive and non-native species cost the UK economy around £1.7bn per year.


Non-native invasive plants can spread rapidly and outcompete native plants for light, space and pollinating insects, leaving native plants unfertilised and unable to reproduce. Aquatic invasive plants clog our waterways and lead to an increase in flooding; they can also remove oxygen from the water, killing local wildlife. Dense stands of invasive plants growing alongside watercourses will die back in winter, leaving the banks exposed and at risk of increased erosion, whilst some invasive plants can cause structural damage.

Due to their impact on the environment, it is illegal under the Wildlife and Countryside Act 1981 (as amended) to plant, or otherwise cause to grow in the wild, certain invasive plants. Soils containing invasive plants on development sites are considered 'contaminated waste', and by law, must be disposed of appropriately. As such, it is imperative that invasive plants are identified at an early stage of the project, to avoid inadvertently causing these species to spread.

Checks for invasive plants are undertaken as standard as part of our Preliminary Ecological Appraisal, and can also be undertaken as stand-alone surveys where required.


Invasive Plants


Durham Dales Ecology undertakes checks to identify the presence of controlled invasive plant species listed under Schedule 9 (part ii) of The Wildlife and Countryside Act 1981 (as amended). It is illegal to plant, or otherwise cause to grow in the wild, any plant on this list. These include:

  • Japanese knotweed

  • Giant hogweed

  • Himalayan balsam

  • New Zealand pygmyweed (Crassula helmsii)

  • Certain species of Cotoneaster

  • Rhododendron ponticum

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