In 2019, drone footage went viral with the headline “Extinct flower rediscovered in Hawaii, via drones”. Scientists at the National Tropical Botanical Garden (NTBG) in Kaua’i were flying drones alongside impenetrable cliffs and spotted a plant, Hibiscadelphus woodii, that was declared extinct in 2016.
In celebration of Fascination of Plants Day, we are following up the story with Ben Nyberg, the GIS and Drone Program Coordinator at NTBG. Nyberg was using drones for creating maps in his personal business before deploying them at NTBG in 2016.
“Pretty quickly, I realised that there are all these cliff environments around and even within our gardens, could be looked at [with drones]”, Nyberg says.
At the beginning of the drone program, NTBG surveyed the 1,000-acre Limahuli preserve, and the team spotted the critically endangered Laukahi plant on extremely steep cliffs. Only 25 plants were known to grow in Hawaii before that sighting, and ten more plants were added to the list after a single drone flight.
“With a few flights, we were able to identify populations of rare plant species, literally 1,000 meters from our visitors centre that we never knew were there before.”
Everyone became excited. NTBG purchased more drones and kept the momentum going. Mapping plant populations helped them understand each species habitat preferences and come up with conservation plans.
Whilst flying around drones and spotting plants sounds somewhat straightforward, but there is more to it. First, the team scouts an area with spotting scopes and finds the best spots to fly the drone.
“I move the drone in, as close to as I can, around 2-5 m to the surface, and snap a still photo. This is done systematically around an area. Then back in the lab, I manually look through each photo. I use Adobe Lightroom and I identify each plant one-by-one. The data is then transferred to GIS software for mapping.”
The technology (both drones and software) is constantly evolving, and Nyberg has to stay on top of it. Lately, they have been trying out drones with zoom lenses, but one of the main problems is getting GPS information near cliffs and image processing.
“We are looking at artificial intelligence and machine learning to pick out these plants but we have so many rare species that they do not have good, reliable training data.”
They need to be absolutely certain about their identification when they come across a species that has been thought to be extinct.
“For now, it looks like it takes a human brain to tell them apart.”
Not everything goes to plan all the time, either. They have lost two drones since starting the program. One might have either malfunctioned or got knocked down by a bird strike. The other one was due to an incorrect automation system where the drone crashed into a tree.
But Nyberg highlights, “it’s much better to lose a drone than a person. It is a minor inconvenience.”
He has collaborators all around the world and works on a myriad of projects. NTBG took the lead in checking the conservation status of over 250 endemic plant species around Kaua’i for IUCN. There are a few more species on his to-do list this week. He is working with the DeLeaves team, trying to add a sampling arm to drones to grab samples from hard-to-reach plants.
He is also working on using drones for reseeding areas and a month ago started a PhD at the University of Copenhagen. He will be looking at the system they have developed in Hawaii, from GIS, modelling hotspots, and then checking them with drones and testing if these tools work in other parts of the world.
