A delicate little plant with a few yellow flowers grows from the rock on Kauai’s knife-edge ridge. The only sounds that can be heard are the wind and the murmur of the waves below. As another drone suspends from the first, it covers the plant with two arms and a blade that cuts through the stem. The device then gently lifts the plant, a member of the genus Schiedea, part of the carnation family. The drone then descends to deliver the tiny specimen to researchers below.
This scene–repeated dozens of times with various plants on the Hawaiian island’s tropical cliffsides as part of a new study–shows how drones can help scientists pluck rare and endangered plants from spots that would otherwise be dangerous, if not impossible, for humans to reach. It is important to collect samples to better understand the plight of these species and to help them save their lives. Warren Wagner, a Smithsonian Institution research botanist, says that this is a great development and use technology to get more information than a person walking around. He was not involved in the study, but he is a research associate at one of the institutions. *
Credit: Outreach Robotics
The study, published recently in Nature Scientific Reports, builds on decades of botanical investigations on Kauai, which has more than 250 native plant species. Botanists have used the island’s steep rock faces to reach certain plants in the past. They often went to great lengths to obtain samples they can grow in a nursery to preserve species at risk. Ben Nyberg, a geographer and drone specialist at National Tropical Botanical Garden wanted to test remote-controlled flying robots in difficult places.
Nyberg used a commercially-available drone to lift a separate robotic unit they built from scratch, the Mamba. The researchers first tried to find a way to make plant-picking arms reach horizontally from a hovering drone when they conceptualized the device. Guillaume Charron, Outreach Robotics’ engineer co-author, said that the idea quickly became complicated. “That’s when I started brainstorming and I came up with the idea to suspend a remote-controlled robotic arms” on cables underneath a drone. The Mamba isn’t able to lift itself so an operator can use its propellers in order to hold it steady and move it sideways exactly as needed.
The Mamba’s sampling components are a foam-padded grasping arms that can move like a wrist and a hook that draws the stem of a plant towards a blade. The team is currently evaluating how to equip the Mamba, including a vacuum that could capture plant material and a sprayer that could spray seeds and medium onto cliffsides for replanting.
Similar drones could also be used to reach other remote areas, such as the Amazon jungle’s tabletop mountains or the sky islands, which are isolated mountain ranges rising abruptly out of the desert. Nyberg is a co-author of the study and is currently completing a Ph.D. at University of Copenhagen. This allows users to reach inaccessible areas .”
The carnation species plucked from Kauai’s high ridges appears to be a Schiedea never identified there before. Its seeds are now growing at the University of California, Irvine, with help from botanists Ann Sakai and Steve Weller–a married couple who have studied Schiedea for more than three decades and were impressed by the information gleaned from the drone’s sampling. Weller states that the drones were able to map the population in detail in a way we couldn’t do by rappelling. “I’m impressed and it’s a really great tool to learn more about these plants .”
*Editor’s Note (10/13/22): This sentence was edited after posting to correct the description of Warren Wagner’s position at the National Tropical Botanical Garden.