Passage 5
The United States has had its most devastating wildfire season on record, with more than eight million acres of land burned across the country this year. Regenerating the forests that sat on much of that land would ordinarily take years and involve hundreds of people manually replanting young trees grown in dedicated nurseries.
Seattle-based DroneSeed has a much faster and more effective solution. The company uses fleets of drones (无人机) to reforest areas that have burned down, dropping what it calls "seed vessels" into areas where they have the best chance of growing back.
The eight-foot drones, up to five at a time flying together on pre-programmed routes, can cover up to 50 acres a day and each carry as much as 57 pounds of seed vessels."We are six times faster than a tree planter out there with a shovel who's doing about two acres a day," DroneSeed CEO Grant Canary said.
Replanting forests from the air is not a new approach, with planes or helicopters often used to scatter seeds. Experts say that method is cheaper and easier than traditional hand planting but may not be as effective."Just throwing forest tree seeds out of airplanes can be successful, and it's a lot cheaper than manual planting," said Ralph Schmidt, a geology professor. "Growing seedlings (幼苗) in nurseries and manually planting them will always have a much higher success rate than aerial sowing, but it is much more expensive."
Selecting the right species of seed and the right place to drop them is key, Schmidt added.
DroneSeed is trying to find a middle ground with its unique seed vessels. The specially designed packets consist of a combination of fertilizers, nutrients and pest deterrents (杀虫剂) that help the seeds take root more effectively- without having to be physically buried in the ground."The vessel absorbs moisture so that it can avoid drying out. It's also pest-proof so that the seed can avoid getting eaten," Canary said.
Drones aren't the only technology the company uses to make replanting more effective. It also deploys Lidar, the sensing technology used by self-driving cars to map the world around them, to create a 3D model of the land. That's coupled with sensors that measure different wavelengths of light to tell the difference between areas of gravel and places where healthy soil may be better suited for trees to grow.

In what aspect is manual planting superior to aerial sowing?