Like many young adults, I once took on a summer position as a tree planter to earn money for school. I planted thousands of tiny seedlings in former harvest areas throughout northern Alberta and British Columbia. I sometimes wondered: what becomes of all those little trees?
I now know at least part of the answer. In Canada, professional foresters visit cut blocks about three years after the tree planters have left, in order to assess their work. Are the seedlings alive and healthy? Is the density and spacing correct? Do the species that were planted make sense for the environment? These establishment surveys are required for every forest-harvest area re-planted in Canada. If the cut block fails the assessment, it gets re-planted.
Establishment surveys take a lot of time. In our research lab, we wondered: can drones help out with this job? Wouldn’t it be great if a forestry technician could show up to a harvest area, deploy a drone, and have it perform the establishment survey automatically? Cut blocks can be difficult to walk around, with lots of stumps, brush piles, and leftover downed trees. Drones could potentially help forest managers complete these surveys faster and more effectively.
In a study published July 18, Corey Feduck and his co-authors showed that yes: drones can help out with at least some of these tasks. Corey compared manual counts of conifer seedlings on the ground to those generated automatically using drone photography. He showed that the two methods largely agreed, with drones finding more than ¾ of the seedlings counted on foot across two experimental sites in western Alberta.
The interesting thing about Corey’s work is that he didn’t use anything special. His drone was a standard off-the-shelf multi-rotor, and his camera was a typical point-and-shoot consumer model. No need for fancy sensors in this job. His one modification was an inexpensive laser range finder, which he strapped to the drone to control altitude during automated flights.
Corey found that he had to be working under the correct conditions, though. He performed flights in the spring, when the only green things in the cut blocks were the tiny “evergreen” seedlings. Come back in the summer, and it probably wouldn’t be so easy!
If you want more information on this study, you can read Corey’s paper here.
This research is part of the Boreal Ecosystem Recovery and Assessment project.
Feduck, C.; McDermid, G.J.; Castilla, G. Detection of Coniferous Seedlings in UAV Imagery. Forests 2018, 9, 432. https://doi.org/10.3390/f9070432