Powered by rain, this seed carrier could help reforest the most remote areas

The world’s forests are under threat. As well as being logged for timber and cleared to make way for agriculture, rising global temperatures are causing more intense wildfires. This year is set to be the hottest on record and has been the worst on record in terms of fires in boreal forests worldwide.

Re-forestation is essential in the fight against climate change and to protect biodiversity, but planting saplings by hand can be slow and labor-intensive.

In recent years, drones have begun to be used to drop seeds onto land deforested by wildfires; a company called Mast Reforestation, formerly DroneSeed, has applied this method in the western United States and beyond, and World Wildlife Fund has used specialized drones to restore rural bushland in Australia. But for a reforest to regrow, dropped seeds have to get into the soil and germinate, and that can be a challenge.

Researchers from Morphing Matter Lab at Carnegie Mellon University, in Pennsylvania, might have an answer. Inspired by nature’s own design, the lab has created an “E-seed” carrier that is intended to be dropped by drones and drill into the soil.

But remarkably, the carrier doesn’t need an energy source to drill into the ground – it’s made from a material that “self-drills” in response to rain.

Lab director Lining Yao and her colleagues looked at erodium seeds for inspiration.
The seeds of this genus of plants have a coil-like “drill” that changes shape when wet, using a “tail” to prop itself up and push more effectively into the ground.

The team created a seed carrier based on the same principle, made from white oak wood that naturally responds to changes in humidity. They chemically treated the wood to make it more flexible when wet, as well as softer and denser so it expands more effectively. Erodium has a single tail, but the seed carrier has three, making it easier to drill into soil.

According to research Yao published in the journal Nature, the carrier has an “80% drilling success rate on flat land,” making it more effective than erodium seeds in the same conditions. After the carrier burrows, the seed is protected from animals and the natural elements, improving its chances of germination.

Tailor-made

In August, the design won the Falling Walls breakthrough of the year award — which is given annually to scientific breakthroughs in academic disciplines — in Engineering and Technology.

So far, Morphing Matter has only tested the seed carriers at sites in Pittsburgh and Changxing, China, but Yao says the lab has received interest from venture capitalists and government agencies around the world wanting to use the seed carriers in reforestation projects.

But she notes that specific types of seed carriers must be developed for different locations, to accommodate different soils and humidity levels, amongst other variants. “We have to tailor the design to local conditions and the seeds of their interest,” explains Yao.

“Desert is very different from the Amazon rainforest and coastal lines around Hawaii.
The partnership has to be very collaborative with local practitioners so we always request them to send seeds and soil for us to validate.”

Providing the technology to projects around the world would require production to be scaled up.

“Most people who reach out want thousands of seeds, they want to grow millions of trees in a year,” says Yao. “I started a small team in the lab to think about mass production strategy, but we definitely want to get more financial and personnel support to make this a larger effort.”

Shu Yang, a professor at the University of Pennsylvania, has been heavily involved in the E-seed carrier project. She says the question of large-scale distribution is an important one.

“You have to look at the efficiency. Right now it is 80% and then once you do a large area, what is the efficiency versus the costs? … Whether people are interested in doing this, I think the success rate is critical.” says Yang.

But in terms of the manufacturing process, Yang believes it will be possible to produce enough carriers to meet demand.

Seed shortage

According to Matthew Aghai, vice president of bio research and development at Mast Reforestation, the e-seed project is a “phenomenal development,” but he adds that for seed distribution to be truly effective, better drones must be made more widely available for reforestation. Typically, with conventional drones, “The technology is not in a place where you can operate with a great degree of control and precision,” he says.

Mast formerly manufactured and used drones for reforestation and still utilizes them in research and development, but doesn’t currently use them in reforestation projects. It also produces millions of seeds annually at the largest seed bank in the western United States, and although it isn’t connected with Morphing Matter Lab, it has consulted with it. Aghai adds that using drones to for reforestation in remote areas requires infrastructure, such as charging stations, which often isn’t available.

But an even bigger challenge could be a shortage of seeds to plant, he says, because storing seeds in banks takes time and seed nurseries need more funding. “There’s actually a broader seed shortage in our industry, a very serious one. That’s the bottleneck for reforesting, not technology.”

Editor’s Note: This story has been updated to clarify Mast Reforestation’s use of drones.