Himalayan balsam, Japanese knotweed and floating pennywort

There are approximately 180 identified non-native species established in the UK and many are causing significant impacts that are difficult and potentially costly to address.

Such species severely damage native ecosystems and, in the case of giant hogweed, are dangerous to humans. Many are difficult and costly to control and some are a particular problem on riverbanks or in aquatic environments because they can be spread by water.

Species that are typically mapped in our aerial surveys include Himalayan balsam, Japanese knotweed and floating pennywort. Species such as these are known to damage buildings and structures, costing the UK roughly £1.7 billion a year.

The Environment Agency estimates that Himalayan balsam now covers up to 13 per cent of riverbanks in England and Wales, with the cost of controlling this one species estimated at around £300 million.

In order to control invasive species, companies have to know where they are. Until recently, the traditional way to do this was through ground based surveys on foot. Although effective, this approach is slow and costly compared to aerial surveys. Also, seeds can be inadvertently spread by staff and vehicles moving between sites.

  • Invasive non-native plant species 1
  • Invasive non-native plant species 2

Aerial surveys for mapping invasive plants

Our state-of-the-art digital cameras are fixed on gyro-stabilised mountings on a specialised survey aircraft, allowing us to survey large areas quickly and cost-effectively to a resolution of up to 1.5 cm per pixel.

Using specialist software, these images are geo-referenced and turned into detailed composite images. Our experienced image analysts then examine the pictures for signs of invasive plant species, such as the pink flowers of Himalayan balsam.

At the same time, we apply algorithms that allow us to automatically create maps showing the various types of vegetation across the landscape. Ground validation can be used to confirm the classification.

We use this information to map the location, type and extent of invasive species. In addition, the very high resolution imagery makes it possible to map any cracks in concrete or tarmac, as well as collapsed river banks or flood defences.

Where invasive plant species are already well established, clients use our maps to inform their mitigation and management efforts. Where species are less well established, our surveys give an early warning.

Regular surveys offer a proactive way to prevent the spread of invasive species.

If you have any queries, please contact David Campbell, associate director.
Alternatively you can email us here. Or call 0161 442 8938.