Drone technology that can reveal what lies beneath the foliage is helping to protect native Scottish plants threatened by invasive species.
The laser-carrying drones use Lidar (light detection and ranging), which operates like radar but utilises light instead of radio waves.
Once the laser pulses are fired at the trees below, the wavelengths bounce back, and a 3D image is created to give an accurate map of the health of the forest floor. This data is combined with information from satellites to give a precise ‘fix’ of the drone’s position.
Led by Edinburgh-based software firm, Ecometrica, its funding partners are the Forestry Commission Scotland, Scottish Orienteering, Woodland Trust and Edinburgh University. Additional support has also come from the UK’s Science and Technology Facilities Council.
Once air-borne, the four-rotor drone may look like a speck in the sky, however it is packed with sensors and is easily audible. The intuitive drone has been surveying forests in the West of Scotland including: Lochgilphead, Ardfern, Auchterawe, Arisaig, Achdalieu and Mandally.
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Generally, Lidar is used by larger aircrafts with humans present on board but unmanned drones could significantly reduce the costs involved.
The aim of the project is to monitor and map how land use is evolving, and how climate change is impacting Scotland’s forests. Traditional photos taken in natural light only show the tree canopy, but Ecometrica’s executive chairman, Richard Tipper, believes the technique offers “centimetre-scale detail”. He added: “It enables you to pick out features that a satellite doesn’t allow you to do”.
The Global Ecosystem Dynamics Investigation (GEDI) Lidar system is currently monitoring large-scale global deforestation from the International Space Station. Tipper said that a Lidar drone covers a much smaller area with each sweep, but the resolution is “an order of magnitude better”.
The objective of this project is to protect native species and, in turn, fight one specific non-native threat.
In the 1700s the flowering shrub rhododendron ponticum, a native of Southern Europe and Western Asia, was introduced to the British Isles.
However, the resulting acidic soil has meant that the rhododendron bushes have spread like a smothering evergreen carpet beneath the cover of the tree canopy. The bushes carry a fungal disease that harms trees and their leaf litter is toxic to native plants. Without Lidar they will continue to spread at an alarming rate, undetected.
The drone data is analysed using a system called Ecometrica Platform, which designs the detailed maps that highlight changes to the ecosystem. Each partner in the project has a different, specific use for the information.
The Forestry Commission is concerned with rhododendrons, while The Woodland Trust wishes to map the remains of native forests.
Edinburgh University will use the information to fuel new research, and Scottish Orienteering require digital models of the terrain as Scotland prepares to host the World Orienteering Championships in 2022.
Mat Williams, professor of global change ecology at Edinburgh University, thinks that the system will play a crucial role in evaluating the effects of climate change, as it can detect the effects of human land use, deforestation, soil degradation, forest fires and drought. In addition, Professor Williams outlined that Scotland is a test bed for technology that could be implemented on a global scale.
Ecometrica is also leading Forests 2020, a UK Space Agency-funded programme to map threats to tropical forests. The data collected in Scotland will be used to see how the techniques could be used in Tropical forests.
“For a long time, we’ve only been able to look at the surface of tropical forests,” Williams added. “We’re hoping Lidar can look in more depth.”
Ecometrica staff hope to determine how many or how few Lidar pulses bouncing back from the forest can provide useful information, and they intend to begin flying Lidar drones in West Africa soon. Many of the threats to the climate there include illegal logging, charcoal burning and our apparently insatiable taste for chocolate.
Ecometrica’s space programme manager, Sarah Middlemiss, emphasised that the project is working with the forestry authorities in Ghana to map the felling of trees in national parks to make way for cocoa. Middlemiss warned that cocoa plants can encroach on the forests even if they are not completely cut down.
“It’s a shade-loving crop,” she explained. “That’s where Lidar is very useful. You can’t map everything from satellites. We need other data sources and Lidar is about the richest you can get.”