Long-term, broad-scale ecological data are critical to plant research, but often impossible to collect on foot. Traditional data-collection methods can be time consuming or dangerous, and can compromise habitats that are sensitive to human impact. Micro-unmanned aerial vehicles (UAVs), or drones, eliminate these data-collection pitfalls by flying over landscapes to gather unobtrusive aerial image data.
A new review in a recent issue of Applications in Plant Sciences explores when and how to use drones in plant research. “The potential of drone technology in research may only be limited by our ability to envision novel applications,” comments Mitch Cruzan, lead author of the review and professor in the Department of Biology at Portland State University. Drones can amass vegetation data over seasons or years for monitoring habitat restoration efforts, monitoring rare and threatened plant populations, surveying agriculture, and measuring carbon storage. “This technology,” says Cruzan, “has the potential for the acquisition of large amounts of information with minimal effort and disruption of natural habitats.”
For some research questions, drone surveys could be the holy grail of ecological data. Drone-captured images can map individual species in the landscape depending on the uniqueness of the spectral light values created from plant leaf or flower colors. Drones can also be paired with 3D technology to measure plant height and size. Scientists can use these images to study plant health, phenology, and reproduction, to track disease, and to survey human-mediated habitat disturbances.
Researchers can fly small drones along set transects over study areas of up to 40 hectares in size. An internal GPS system allows drones to hover over pinpointed locations and altitudes to collect repeatable, high-resolution images. Cruzan and colleagues warn researchers of “shadow gaps” when collecting data. Taller vegetation can obscure shorter vegetation, hiding them from view in aerial photographs. Thus, overlapping images are required to get the right angles to capture a full view of the landscape.