The impact of invasive plant species on development

The discovery of invasive plant species on a development site can be great cause for concern for developers, with the potential to delay progress and result in high remediation costs.

It is believed that invasive non-native plant species cost the British economy billions per year. However, the costs to a developer can be significantly minimised by seeking expert advice at the very start of your project, before the land is acquired.

What are invasive plant species?

An invasive plant species is a plant that has overpopulated an environment, due to direct or indirect introduction. In most cases, an invasive plant has the potential to negatively alter its new environment, invading habitats and causing ecological, environmental and even economic damage.

Non-native plants are those that have been introduced outside their natural range by humans. Native species can also become invasive within certain ecosystems due to alterations of the environment.

The most commonly found invasive plant species found around development sites include New Zealand Pigmyweed, Cotoneaster Species, Himalayan Balsam, Giant Hogweed and Japanese Knotweed. They are considered ‘invasive’ due to their rapid rate of spread, suppression of other species, and impact on wider environments such as waterways.

What damage can they do?

Invasive plant species can cause significant complications for land owners and developers, and their impact is so serious, they are considered one of the greatest threats to biodiversity worldwide.

The damage caused by invasive plants includes:

  • Altering ecosystems and habitats – some invasive plants can change the chemical composition of soil or clog up waterways, leading to flooding.
  • Outcompete native plants, threatening the long-term survival of the species.
  • Be costly to eradicate and restore degraded environments.

 What legislation should developers be aware of?

There are numerous regulations to help protect the environment from invasive plant species, and developers must make sure they are aware of such legislation.

The Wildlife and Countryside Act (1981) states that developers are legally required to prevent invasive non-native plant materials on their land from spreading into the wild and causing a nuisance. They must also prevent harmful weeds on their land from spreading to neighbouring property.

Schedule 9 of the Wildlife and Countryside Act (1981) also makes it an offence to plant or cause to grow invasive wild plants.

EU Regulation on Invasive Alien Species, which still applies in the UK, lists 36 plants that should not be sold, planted or caused to grow.

The Infrastructure Act (2015) also includes new provisions to control invasive non-native species in England and Wales. This includes two levels of control, including a species control agreement and species control order. Only those species listed on Schedule 9 of the Wildlife & Countryside Act can be subject to these control measures.

Preparing a site for development

The discovery of invasive plant species on a development site can cause major problems for developers. If they are not identified at the early stages of planning, and detailed expert surveys are not conducted, it can cause costly delays to construction.

With legislation stating that landowners and developers are responsible for managing invasive species, a number of investigations are necessary, with the help of trained experts.

It is vital that detailed checks and risk assessments are carried out for non-native invasive species as part of the initial feasibility studies and surveys.

An ecological appraisal should also identify any invasive plants. This will include advice on initial findings, mitigation options to avoid impact and enhance biodiversity, and a report to submit to the planning authority, providing findings, compliance, enhancement options and supporting data.

If your surveys find invasive plants on site, work can still proceed, but a plan to remove and safely dispose of them will be required. An ecologist can draw up a method statement, including an ecological protection plan and species protection plan, where necessary.

Call in the experts

From initial site surveys and ecological appraisals, to management strategies and plans, it is important to consult with trained ecologists on invasive plants as soon as possible.

Engain has a team of experienced ecologists that can support you throughout the process and ensure you remain compliant at all times.

To discuss how Engain’s environmental consultants can ensure your project runs smoothly from the start, call 01225 459564 or email

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