- Issue: Summer 2021
Shooting laser beams at the Earth might sound like the stuff of science fiction, but in fact these focused light pulses are at the heart of a powerful conservation tool. Lidar (light detection and ranging) uses laser-based imaging to yield highly detailed three-dimensional visuals, which conservationists can use to study landforms, vegetation, seafloors, and riverbeds. By combining that 3D data with traditional satellite and aerial imagery and field data, scientists can unlock a treasure trove of ecological information about a place, from what species it holds to how much carbon it stores.
Light from above
Airborne lidar surveys typically use a laser scanner mounted on an airplane. The scanner emits pulses of light, and its receiver records the precise time it takes for the light to reflect off of objects below and return. The collected information, combined with data from the plane’s navigational systems, reveals a detailed 3D picture of the topography and vegetation below.
Lidar can scan an area with hundreds of thousands of light pulses each second, creating a 3D point cloud. A single pulse can have multiple returns, revealing details like forest density, canopy height, and even tree species.
Lidar 3D mapping can detect subtle changes in landscapes over time, such as riverbank erosion or the movement of sediment. It can also quickly map sudden changes: After severe wildfires stripped hillsides of vegetation in Southern California, the US Geological Survey used lidar to model the potential for heavy rains to cause flooding and mudslides.
WWF has been working with lidar since 2008, and the technology has been especially helpful in measuring the carbon content in natural habitats. In 2017, WWF and partners created a map of the carbon stored in every hectare of the Democratic Republic of the Congo’s forests to help the nation monitor its forest cover and assess carbon emissions from deforestation. WWF-Canada and McMaster University’s Remote Sensing Lab plan to release the first nationwide estimate of carbon storage in natural habitats across all of Canada later this year.