Drone seed planting sees some success; Improvements can be made
TRUCKEE, Calif. — Groups are seeing positive results from a pilot program that used drones to plant seeds in forests impacted by wildfire.
In April 2021, the Sugar Pine Foundation, along with the Forest Service, Desert Research Institute and Flying Forests used drones to drop seed balls in hard to reach areas within the Loyalton Fire burn scar northwest of Reno.
SPF, a nonprofit which aims to restore the local sugar pine population by cultivating and planting blister rust resistant trees, used their supporters to gather nearly 90,000 Jeffrey Pine seeds for the project.
The seeds were mixed into balls with nutrients, ingredients to help the balls stick together and cayenne pepper and rotten eggs that act as animal deterrents for critters that might be interested in eating the seed balls.
Flying Forests, a partnership between WeRobotics and Beta Earth Venture Studio, developed the technology to use the drone to distribute the seeds and DRI provided the drones and drone pilots.
The groups dropped 25,000 seed balls from a height of 65-100 feets. The seed balls were placed about 7-10 feet apart. In total, about 75,000 seeds were distributed over 25 acres.
SPF Executive Director Maria Mircheva said that after accounting for seeds not taking and tree mortality over the years, they are expecting about 50 trees per acre to grow.
A study done by University of Nevada Reno’s Great Basin Fire Science Exchange program has shown some positive initial results.
According to the UNR report, the project site was monitored four times following the seeding. The scientists were collecting data on seed ball distribution and final resting place condition, germination and seedling growth.
“Even with the harsh post-seeding conditions, the team located 10 seedlings in November 2021, suggesting establishment of maybe 100 seedlings,” the report stated. “Although a low rate of establishment, it was better than expected and ultimately not the goal of this trial.”
Part of the goal of the trial is to tweak and perfect the technology and methods to use in other burn scars and ultimately help forests recover faster from wildfires.
“I was very excited to see the seedlings that grew from the drone planting last year in the Loyalton fire scar,” Mircheva said. “It did not happen right away; it seemed that some seeds survived until the fall rains and then sprouted. Unfortunately, only about 1% of the seed grew into seedlings but this experiment will contribute to gaining more knowledge on how to best use this new technology. Our partners will be doing some more drone plantings and hopefully hone in on how to increase the success rate.”
SPF currently enlists volunteers to hand-plant seedlings and while that has been successful, it limits the amount of trees and where they can be planted. On the other hand, because they are planting already established seedlings, the likelihood of success is greater than just planting seeds.
“From our initial project, the traditional method of hand planting seedlings yields better survival and is more cost effective than drone planting. That said, if the right blend of conditions arise to support another drone planting with improved technology, we are open to it,” added Tressa Gibbard, program manager for SPF. “For instance, using drones makes sense if we secure specific funding and permission by a landowner with a need to replant an otherwise inaccessible site — like a steep slope in a burn scar without good road or foot access.
“The beauty of drones is that they can reach places that are typically hard to reseed,” Gibbard continued. “The main difficulty in our region is that it is hard to get seeds to germinate in such arid conditions. Plus, hungry animals quickly gobble up the ‘free food’ we scatter on the ground before the seeds can sprout.”
The UNR report included several lessons and improvements including studying the success of fall plantings versus spring plantings.
Suggested improvements to the seed balls themselves included, fine tuning the clay to compost ratio; seed balls delivered in this project were likely clay heavy, anticipating fluctuating seed availability, developing balls that can accommodate small seeds or a mix species without compromising emergence and testing predation deterrents to prevent animals from eating the balls.
“In difficult to access or sensitive places, using drones for post-fire seeding has the potential to be a game changer, but drones are not for every situation. In many cases, drone seeding cannot replace hand-planting or traditional seeding, but it offers another option and will be valuable in certain places,” the report concluded.
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