Iwanuma is a quaint and quintessentially Japanese beach town on the Sendai Coast, a two-hour train ride north of Tokyo, in Miyagi Prefecture. Rolling sand dunes line the coast, and a thin forest of black pines spreads inland to a wide band of rice paddies and modest farmhouses. Like dozens of small communities along this stretch of coast, it’s been farmed for hundreds of years, left mostly to itself as Japan developed and urbanized.

When the Great East Japan Earthquake pushed a tsunami against the coastline on March 11, 2011, Iwanuma was washed over by waves that rushed inland for miles and destroyed almost everything in their path. The parts of Iwanuma inundated by the tsunami were mostly agricultural lands, but the death toll still reached an estimated 180 people. In all, more than 15,000 people died as a result of the earthquake and tsunami. Most drowned.

It was a devastating catastrophe for a country all too familiar with disasters, natural and human-made. But it was also something of an alarm to many people in seismically hyperactive Japan who have become newly energized by efforts to prevent similar destruction from the inevitable tsunamis of the future. One approach has gained considerable attention: the accelerated planting of “forest walls” as wave barriers. Hundreds of thousands of saplings have been planted along the coastline so far, and advocates contend the forests that grow will significantly slow and dissipate the force of tidal waves to come. It’s a landscape infrastructure approach that both reforests coastlines and protects communities.

However, as mass plantings continue up and down miles of coastline, some people are concerned that these forest walls are causing more damage than good, harming coastal ecologies that are rebounding naturally and providing their own potentially more robust protection from surging waters.

A blanket of white clouds drapes the Iwanuma beach on a brisk day in late May as a windy drizzle blows clumps of grasses and morning glories along the recovering Sendai coastline. The ocean’s waves are a distant static, muffled and hidden behind a two-meter-high concrete embankment that’s been built as a primary protection from future tsunamis. On the land side of the embankment, a crowd of roughly 4,000 people has gathered, volunteers—community groups, families, and corporate teams—who have come for a forest wall planting event that will put more than 30,000 saplings in the ground in a matter of hours.

The event has been organized by the Morino Project, a foundation formed in the aftermath of the 2011 tsunami by the former Japanese Prime Minister Morihiro Hosokawa and the famed plant ecologist Akira Miyawaki. The foundation has been organizing planting events like this along the coast, using rubble from the tsunami to build berms upon which native trees are planted. It’s a form of disaster prevention infrastructure that the foundation believes will grow into life-saving forests. Their goal is to plant one million trees; so far, volunteers like those gathered today have planted 400,000. “The volunteers have a lot of passion,” Hosokawa says.

It’s a festival-like atmosphere on the sand, where large groups in matching neon vests mingle, vendors sell rice balls and brined cucumbers, and kids pose for photos with fuzzy costumed mascots. After a two-hour opening ceremony of speeches emceed by a Japanese comedian and closed out by Hosokawa, the volunteers file out toward their assigned planting plots. Just beyond, a sloping stretch of tilled earth sits ready for planting. It is roped off into 100-square-meter sections, each stocked with pallets of saplings, shovels, water buckets, and rice straw. The groups of volunteers, in the bright shirts of various sponsors or organizations, form a boisterous and colorful ribbon as they march to their plots.

The planting plots have been carefully arranged, and the saplings specially selected through what’s become known as the Miyawaki Method, developed by Akira Miyawaki, who is also a professor emeritus at Yokohama National University. His method, developed over decades, is based on carefully choosing and growing pioneer and secondary sapling species from the acorns of indigenous local trees in a tight, random planting. The proximity of the saplings encourages competition and speeds up the process of growth. Miyawaki claims this method can grow mature forests within 30 years, instead of the 150 to 200 years it would normally take. Though Miyawaki, now 89, is no longer actively involved in the volunteer planting events, his method is strictly followed. And his adherents argue that it should be used more widely.

Miyawaki began developing this approach in the late 1950s when he was in Germany studying something known as the Potential Vegetation Method, which assesses what vegetation would be expected to match a region’s environmental constraints without human intervention. Bringing this method back to Japan, he mapped all regions of Japan to determine their potential vegetation. He found that human intervention had been devastating to the country’s native forests, replacing all but 0.06 percent of them with nonnative growth. “Japan’s forests today are fake forests, not real,” says Makoto Nikkawa, the secretary general of the forest planting project. “Miyawaki feels it is his mission to revive and regenerate the true natural forests of Japan.”

Over the past half century, his method has been used to plant forests throughout Japan and around the world. But since the tsunami, Miyawaki has focused not just on regrowing native forests, but using his method as a form of disaster prevention. “These are life-saving forests,” says Eri Ishimori, a Morino Project coordinator at the Iwanuma planting event. They are also reminiscent of an ancient form of Japanese land management, or satoyama, a term referring to the mixed ecosystem surrounding traditional Japanese rural communities. It’s not virgin forest but a product of many years of careful tending and stewardship—not “man-made” or “natural” but an amalgam. The black pine forests that once lined the Sendai coast, planted gradually over the past 400 years to protect inland rice paddies, are an example, and they’re still standing just inland from the shore.

Once the parading volunteers arrive at their planting sites, a ballet of landscaping begins. Teams of a dozen or so begin soaking the saplings in buckets of water, then pushing them down into the upturned soil. After the saplings are in the dirt—a few hundred per team—a bedding of rice straw is spread out over the ground to retain moisture. Within an hour, all 30,000 saplings have been planted.

For the Morino Project, the participatory nature of these events is crucial to generating awareness of the effort to efficiently plant thousands of saplings in one afternoon and also to engage the community in a meaningful and spiritual way. “Planting a tree is one of the behaviors most internalized by human beings,” Nikkawa says. “Planting a tree in soil is akin to planting it in your heart.”

A few miles up the coast, a different type of forest is taking shape. A patchwork of untouched ecological zones runs from the sea inland, with sandy beaches, dunes, coastal forests, and wetlands. These ecosystems have naturally recovered since the tsunami, and a group of local ecologists led by Yoshihiko Hirabuki, a plant ecologist and professor at Tohoku Gakuin University in Sendai, has adopted them as an ecotone monitoring site.

On a bright but windy spring day, Hirabuki stands high on the concrete embankment overlooking wild mounds of sand dunes that lead to the sea. They are dappled with the light pink flowers of morning glories, a native pioneer species that has been steadily recovering since the tsunami. The concrete embankment, effectively a seawall, is an impenetrable barrier to the morning glories and many other species, plant and animal. “Many foreign visitors say that Japanese people are getting along with nature very well, in a Buddhist way, and that Western people only want to conquer nature,” Hirabuki says. “But in reality, we are not so different.”

Stepping down from the embankment into the marshland zone of the monitoring site, Hirabuki wades through shrubby understory plants that spring out from under fallen trees, pointing out new pioneer tree species that mingle with tall trunks of black pines, some dead, some recovering. The ground is littered with pine cones, acorns, branches, and a plethora of forest oddities. The soil is textured and rich, and plant life is recovering wildly, and quicker than expected, as insects, birds, and even small fish are returning at a rate that suggests this is a healthy, recovering forest ecosystem.

After the tsunami, the government granted Hirabuki permission to study the coastal damage. He found this area, with damaged and unexpectedly undamaged areas sandwiched together in a zigzag pattern. He was mesmerized, and contacted various ecologists with specializations in both flora and fauna to better understand the ecological significance of this phenomenon. Because some areas seemed almost completely unscathed by the tsunami, he thought it might offer some clues about how areas could withstand the next disaster. The group quickly organized, and it successfully petitioned the government to allow for the area to become a protected monitoring site.

After large disturbances, Hirabuki says, residual organic matter and organically derived structures and spatial patterns called “biological legacies” can propel ecosystem recovery. Essentially, he says, the landscape has an ecological memory that the tsunami helped uncover, and if left alone, it will rebound naturally, allowing for the full development of biodiversity. The disturbance also created heterogeneous environments for plant establishment, such as pits, mounds, and remnant canopy trees. The group believes that monitoring the biological legacies’ effect on the ecological process can provide insight into the best practices for restoring ecosystems in the wake of disaster. “The regeneration strategy has an effect on biodiversity,” Hirabuki says. “Planting new trees is important, but we have to preserve existing trees, too. Maybe we don’t need to grow trees artificially. Maybe we can do it naturally.”

The group comes out twice a month and records the regenerative changes in flora and fauna. Because the tsunami was considered by some scientists a once-in-a-thousand-year event, there is no record of an ecological recovery of this kind, which makes for valuable academic research, Hirabuki says. And because the tidal wave washed away all traces of the centuries’ worth of satoyama, or human-influenced landscapes, what is currently emerging can be seen as historical ecological data. “The natural boundary between seaside and inland used to be the entire coastline. Now we only have a few hundred meters,” Hirabuki says. “Maybe when we come here we can recall our ancient memories, or can imagine what these areas looked like as virgin forests.”

Hirabuki’s main concern as a landscape ecologist is how not to obstruct nature in the face of rehabilitation. He and his colleagues have concerns about the way the forest wall project is being implemented.

The Morino Project’s newly planted forest embankments were originally the historic black pine forests planted to protect rice paddies from coastal elements. “The important thing is, the people gradually planted the black pine trees over 400 years,” Hirabuki says. They managed the forest along the way, planting and thinning, so the forest developed in layers that allowed for biodiversity to take shape. “One of the worst problems in these coastal areas is that this man-made embankment is getting made all at once. A lot of ecologists are complaining this is more disastrous than the tsunami/tidal wave itself,” Hirabuki says.

He and his colleagues also worry that the species used in the planting project are evergreen, whereas broadleaf deciduous trees would better match the conditions of the region. The Morino Project says it uses native species, but Hirabuki argues that there is no evidence of what truly native species existed in this region, as humans have been manipulating the landscape for hundreds of years.

Walking out among the fence-like wooden embankment structures that have been built to separate planting zones, Hirabuki is concerned about how they may obstruct important pathways necessary for the mating of many rare species of insects native to the sand dune climate, including an important native bee in the region. “Making artificial inland environments is possible due to modern day technology,” Hirabuki says, “but ecologically speaking it doesn’t make sense.”

Despite their differences both groups are moving forward with their projects. The Morino Project has faced some setbacks owing to difficulties with land acquisition and bureaucratic processes, but the principals continue to work toward their goal of planting one million trees and are regularly holding planting events along the coast. “Forests have a healing effect on people’s spirits, and this is good for the local people,” says Hosokawa, the Morino Project cofounder and former prime minister.

Hirabuki and his team of ecologists continue to visit and take measurements at their ecotone monitoring site. The group has received a small amount of funding through the Ministry of Education, and local volunteers have animated the site with ecozone maps and a blog of biological discoveries. “The effect of reviving nature is incredible and is enhancing tsunami victims’ ability to regain confidence,” Hirabuki says.

Each approach is limited in certain ways, but they are both creatively taking action in the face of potential disaster. How well each approach works may not be known for years or decades. In the meantime, they’re both trying to appreciate the benefits that nature can provide right now, while also looking to the potential and likely tsunamis of the future. It’s what people in this region have done for hundreds of years.

Kathleen Gmyrek is a landscape designer based in Berlin.