South Korea’s Forests Are Aging. What Comes Next?

On a smoky afternoon in late March, as the wind carried ash across the blackened hills of Bonghwa, a mountain town nestled deep in North Gyeongsang Province, the forest smelled like burned resin and silence. Pine trees, once the pride of national reforestation, stood blackened or collapsed, their trunks charred, their needles turned to dust. The wildfire that swept through here days earlier had spread fast — too fast — feeding on wind, dryness, and something older: a structural vulnerability rooted decades deep.

These were not wild forests, nor ancient ones. They were planted by hand, by policy, by a national effort that once defined modern South Korea. In the decades after the Korean War, when mountains were bare and erosion was constant, a massive reforestation campaign blanketed hillsides with pine saplings. It was a symbol of recovery, of green growth rising from ashes — and it worked. By the 1990s, more than 60 percent of South Korea was forested, a remarkable transformation from the ecological collapse of the 1950s.

But forests, like societies, age. And what once stood as a monument to regeneration now stands — sometimes literally — in flames. The pine trees planted in the 1970s are now aging into uniform, fire-prone stands. They are forests that look full, but lack resilience. Forests that were made to grow fast, not necessarily to last.

The Legacy of a Green Miracle

In the early 1960s, aerial photos of Korea showed something startling: mountains stripped bare, ridgelines like exposed vertebrae, and erosion so severe that even the rivers ran brown. After the war, the nation’s forests had been nearly erased — felled for firewood, cleared for farmland, bombed, burned, and neglected. Rebuilding was not just about industry and infrastructure; it was about covering the bones of the land.

Under President Park Chung-hee, the government launched an ambitious National Reforestation Project in 1973, mobilizing soldiers, schoolchildren, and village cooperatives in a mass planting effort. It was a top-down, all-hands-on-deck campaign that blurred the line between civil duty and environmental necessity. The most common species chosen? Korean red pine (Pinus densiflora) — fast-growing, hardy, and adaptable to Korea’s mountain soil. It became, for better or worse, the default tree of rebirth.

By the 1990s, international observers were calling Korea a model of reforestation success. Forest cover had expanded from less than 40% in 1950 to over 65%, with some estimates now placing it above 70%. From the sky, the country had turned green. But from the ground, something else was happening.

The pines were growing — but they were growing old. And because they had been planted at the same time, in similar conditions, with similar genetic stock, they were aging together. The result? Vast monocultures with shallow ecological foundations. Uniform forests may look lush, but they function more like fields of crops than wild ecosystems. They’re vulnerable to the same shocks — pests, drought, fire — and they lack the diversity needed to recover on their own.

It was, in many ways, an ecological miracle. But miracles rarely age well without maintenance. And forests, unlike bridges or buildings, cannot simply be patched or reinforced. They live and die by rhythms we often fail to notice until it’s too late.

How Monoculture Fuels the Flames

When the fire reached the edge of the pine stand in Bonghwa, it didn’t slow down. It accelerated — feeding on resinous bark, dry needles, and a decades-old accumulation of leaf litter. The wind, already fierce, lifted embers into the sky and carried them across valleys. Flames didn’t crawl; they leapt, igniting distant ridgelines in minutes. Local officials called it one of the fastest-moving wildfires they’d seen in years. It wasn’t just the weather. It was the forest itself.

“A pine forest is like gasoline when it’s dry,” one firefighter said. “There’s nothing to stop it. No gaps. No breaks. Everything burns the same.”

Monoculture planting — the widespread practice of reforesting with a single species — made sense in the 1970s. Pine trees grew quickly, stabilized soil, and survived harsh conditions. But ecologically, they are brittle. In a mixed forest, species respond differently to fire; moisture retention varies, leaf types break up fire paths, some trees survive. But in a pine-dominated monoculture, especially one of the same age and density, a fire moves like it’s been invited in.

Korea now faces this reality more frequently. Wildfires are increasing in size and intensity. In the last two decades, major fires in Gangwon-do, Gyeongsangbuk-do, and other mountain regions have repeatedly overwhelmed firefighting capacity. In 2022, the fire that swept through Uljin and Samcheok burned nearly 20,000 hectares — the largest wildfire in Korea’s modern history. The vast majority of affected areas were pine forests planted in the postwar decades.

And the threat doesn’t stop with fire. Pine wilt disease, caused by the invasive pinewood nematode (Bursaphelenchus xylophilus), has devastated hundreds of thousands of trees since it was first detected in Korea in the 1980s. The disease spreads more easily in uniform forests, where trees share similar genetics and vulnerabilities. The result: entire stands die off in just a few years, turning green hills into patchworks of dead trunks — dry fuel for the next fire.

What made monocultures attractive in a time of urgency now makes them dangerous in an era of instability. The climate is hotter, the seasons more erratic, and the forests more flammable than ever before. And yet, many of these forests are treated as if they remain the same resilient guardians of decades past.

From Green Walls to Living Systems

For a long time, Korea’s forests were measured by color — green meant progress, green meant recovery. From the sky, the patchwork of hills appeared lush and thriving. But from the forest floor, the story is different: many stands are uniform, overgrown, and ecologically thin. A living forest, ecologists say, is not one that simply covers space. It’s one that breathes in layers — uneven, diverse, and full of interaction.

In recent years, a quiet revolution has begun in Korean forestry circles: the move from monoculture reforestation to ecosystem-based forest design. In Gyeonggi Province, new planting guidelines prioritize mixed stands of pine, oak, birch, and zelkova. These species vary in root depth, moisture retention, and fire resistance — forming what scientists call “functional diversity.” Not only does this buffer against fire and pests, but it increases carbon sequestration, supports pollinators, and restores soil.

A healthy forest is also structurally diverse. It has layers: ground cover that holds moisture, shrubs that shade the soil, saplings in the understory, and towering elders that filter sunlight. This complexity breaks the momentum of fire, absorbs heavy rain, and shelters everything from fungi to birds. But these layers don't form overnight — and they don’t survive long without care.

Forest managers are exploring selective thinning and rotation systems that gradually phase out vulnerable stands and introduce new growth. This avoids clear-cutting while creating a mosaic of ages and species, making the landscape more resilient. The Korea Forest Service is also experimenting with firebreak zones, biochar production, and controlled burns — techniques long used in other fire-prone regions like California and Australia.

Equally important is local involvement. In places like Jeongseon and Hadong, community forestry initiatives are showing early promise. Villagers manage small forest parcels for edible herbs, mushrooms, and even low-impact timber. Forest therapy trails — designated healing walks through carefully maintained woodlands — are being linked with rural tourism. These programs not only create income but foster the sense that forests are not just national assets, but communal responsibilities.

But systemic change remains slow. Much of Korea’s forestland is still governed through centralized, top-down planning. Local governments often lack the flexibility to implement region-specific strategies. Stewardship — real, adaptive, place-based care — requires more than ecological knowledge. It requires cultural change, institutional trust, and the willingness to see forests not as fixed achievements, but as evolving relationships.

Rethinking Arbor Day — From Symbol to Stewardship

For many Koreans, Sikmogil — Arbor Day — conjures memories of childhood. There were saplings lined up in schoolyards, miniature shovels, and plastic name tags carefully tied to a slender branch. The act of planting a tree was simple, ceremonial, and deeply symbolic. It said: we are helping the land recover. We are building something that will last.

But that symbolism, once vital in a post-war nation rebuilding from ruin, now feels incomplete. In a climate of intensifying wildfires, invasive pests, and aging forests, the question is no longer just “Can we plant a tree?” but “Can we care for a forest — for decades, together?”

Arbor Day could be reimagined for this era — not as a one-day ritual, but as a week of ecological awareness and intergenerational learning. Imagine students walking through nearby forests with sensors and notebooks, learning to identify soil health, canopy gaps, and fungal growth. Imagine communities mapping their local forest’s age structure or biodiversity, asking what species belong and what interventions are needed. Imagine a festival not of planting, but of planning — a national check-in on the health and future of our forests.

In some schools, this future is already arriving. A few have partnered with forest educators to create “living classrooms,” where students observe seasonal changes, track the growth of native species, and monitor carbon uptake using simple tools. Others engage with digital forest mapping or simulate climate scenarios through game-based learning. These aren’t simply environmental activities — they are training in stewardship, in the idea that forests are not static backdrops, but living systems we are part of.

Rethinking Sikmogil does not mean discarding tradition. It means deepening it. The act of planting a tree will always be powerful. But in an era of ecological precarity, the more radical gesture may be to teach a child how to care for a tree — not just today, but next year, and ten years from now. A tree is not just planted; it is accompanied.

The Forest That Grew With Us — And What Comes Next

When the smoke finally cleared in Bonghwa, what remained wasn’t silence, but a kind of stunned stillness. The trees that had once framed the town’s ridgelines now lay collapsed, blackened into bone-like shapes, or left standing like ghosts. From a distance, the hills looked skeletal. Up close, you could see the blistered bark, the ash that clung to the air, and the charred pine cones cracked open by fire. The forest was not gone — but it was changed.

“We used to think of the trees like guardians,” a local forestry worker told me, gesturing to a burnt slope. “They were planted to protect us. But maybe we’ve asked them to stand still for too long.” There was no anger in his voice, only recognition — that the forests, like the people who planted them, had aged in place. And that now, a different kind of relationship was needed.

South Korea’s reforestation story is still one of the great environmental achievements of the 20th century. But achievements can age. What was once radical — planting a nation’s worth of trees — is no longer enough. The trees have grown tall, and now they must grow wise. Or rather, we must.

A sustainable forest isn’t just biodiverse or fire-resilient. It’s a forest that’s lived with — visited, observed, cared for, adapted over time. It’s a forest that changes shape as the world changes around it. That offers shade without asking to be forgotten. That’s not just remembered, but remembered with.

The trees planted in the 1970s helped heal a wounded country. The question now is not how many more we can plant, but whether we know how to live with the ones already here. The next chapter of this forest will not be written by shovels, but by choices. Long-term ones. Quiet ones. And if we’re lucky, shared ones.