South Korea packs a striking range of ecosystems into a landmass roughly the size of Indiana. From subalpine conifer forests on volcanic peaks to vast tidal mudflats teeming with migratory shorebirds, the Korean Peninsula’s southern half sits at a biogeographic crossroads where temperate, subtropical, and even boreal influences overlap. That overlap, combined with dramatic topography and a complicated modern history, has shaped a landscape where globally significant biodiversity coexists with one of the world’s most densely urbanized societies. The tension between those two realities runs through nearly every aspect of South Korea’s natural heritage.
The Mountain Spine
The defining physical feature of South Korea’s landscape is the Baekdudaegan, a continuous mountain range that runs roughly north to south along the eastern side of the peninsula before branching into lower ridges across the interior and south. This range connects most of the country’s forests from lowland valleys up through montane and subalpine zones, and ecologists recognize it as one of South Korea’s most important biodiversity hotspots.1Journal of Ecology and Environment. Elevational distribution ranges of vascular plant species in the Baekdudaegan mountain range, South Korea The tallest peaks in this system, including Seoraksan in the northeast and Jirisan in the south, reach above 1,500 meters and host plant communities found nowhere else in the country.
Because the Baekdudaegan acts as an unbroken corridor of forested habitat, it serves as a migration route and gene-flow pathway for wildlife that would otherwise be fragmented by the cities and farmland that dominate the western coastal plains. Simulations of South Korea’s ecological connectivity confirm that biodiversity is already deteriorating where urbanization has carved up habitats and reduced connectivity, but also that sustained forest conservation along mountain corridors can buffer those losses.2Ecological Connectivity of Forest Ecosystems. Republic of Korea: Predicting Shifts in Forest Biodiversity In practical terms, the Baekdudaegan is the country’s ecological backbone, and its health determines the viability of much of the inland wildlife.
A Forest Reborn
South Korea’s forests were devastated in the early and mid-twentieth century. Decades of Japanese colonial timber extraction, the Korean War, and desperate fuel-wood harvesting by a poor postwar population left the mountains largely stripped. By the 1950s, hillsides across the country were barren or severely degraded. The reforestation campaign that followed, beginning in earnest in the 1960s and continuing for decades, is now considered one of the most successful large-scale forest restorations in modern history. By 2020, the national growing stock volume had reached about 165 cubic meters per hectare, a more than 29-fold increase from the postwar low.3PubMed Central. Reexamining Korea’s successful forest restoration through the revised PDCA framework
The recovery was not just cosmetic. Research examining plant biodiversity across restored landscapes found that continuous forest management had a measurable positive impact on biodiversity, offsetting the negative effects of past urbanization. Improvements in forest habitat quality also reduced the projected damage from climate change, a finding that researchers highlighted as evidence that economic development and urbanization can run in parallel with biodiversity gains when forest policy is sustained.4Journal of Environmental Management. Forest management can mitigate negative impacts of climate and land-use change on plant biodiversity: Insights from the Republic of Korea
That said, a plantation forest and a natural forest are not the same thing ecologically. Comparisons between Korean white pine plantations and oak-dominated natural deciduous forests reveal stark differences in structural complexity and species turnover. Natural deciduous forests showed much higher rates of new tree recruitment, with diverse species continuously entering the stand, while pine plantations showed almost no new tree recruitment at all during monitoring periods. Over time, some of these natural deciduous forests appear to be transitioning into mixed forests as Korean white pine saplings establish themselves underneath the oaks, adding yet another layer of complexity.5Journal of Ecology and Environment. Comparison of stand structure and growth characteristics between Korean white pine plantation and oak-dominated natural deciduous forest by thinning treatment South Korea’s forests are green again, but the ecological maturity of those forests is still a work in progress.
The Korean Fir in Decline
Among the most visible casualties of climate stress in South Korea’s mountains is the Korean fir, Abies koreana, a conifer found only on a handful of high-elevation peaks in the country. The species is the only fir tree endemic to the Korean Peninsula, and its populations are isolated on mountaintops where conditions are cold enough to sustain them. In recent years, those populations have been in steady decline. Under moderate-to-severe climate projections, more than half of the Korean fir’s suitable habitat and over 90 percent of its population could be lost by the end of the century, with the sharpest losses occurring in areas that currently support the densest stands.6Trees, Forests and People. Identifying climate and topographic factors for Korean Fir (Abies koreana) of Mt. Hallasan using machine learning under projected climate change scenarios
The causes are not limited to gradually rising temperatures. Researchers studying Korean fir dieback on Mount Jirisan found that an abnormal winter drought in 1999, when precipitation during the cold season dropped to under 5 percent of what falls during the growing season (compared to a normal average of about 18.5 percent), likely caused widespread root damage through soil frost and heaving. That single drought event appears to have increased Korean fir mortality across every size class.7Journal of Plant Biology. Abnormal Winter Drought-Induced Transient Dieback of Korean Fir in the Montane Forests of Mt. Jirisan, South Korea The Korean fir’s predicament illustrates a broader pattern: species locked into high-elevation habitats have nowhere to go when their mountaintop environments shift.
Tidal Flats and the Shorebird Highway
South Korea’s west coast faces the Yellow Sea, and along that coastline lie some of the largest tidal flats in the world. These mudflats form a critical link in the East Asian-Australasian Flyway, a migration route used by tens of millions of waterbirds traveling between breeding grounds in the Arctic and Siberia and wintering sites as far south as Australia and New Zealand. The Korean tidal flat system is extensive, and its biological importance has been studied in terms of spatial scale, geographic distribution, and biodiversity.8ScienceDirect. The Korean tidal flat of the Yellow Sea: Physical setting, ecosystem and management
Surveys of shorebird use across Korean tidal flat sites found that every surveyed area qualified as internationally important for at least one shorebird species. Yubu Island stood out as the single most significant stopover site, supporting 13 species at internationally important population levels and hosting roughly 90,000 individual shorebirds during a 2014-2015 survey period.9Avian Conservation and Ecology. International importance of tidal flats in the Republic of Korea as shorebird stopover sites in the East Asian–Australasian flyway The concentration of birds at these sites makes them both ecologically vital and ecologically fragile; land reclamation projects along the west coast have already eliminated large areas of tidal flat, and the remaining sites bear a disproportionate burden for sustaining flyway populations.
One of the most charismatic species dependent on this coastal zone is the black-faced spoonbill, an endangered wading bird with a global population of only a few thousand. The majority of the world’s black-faced spoonbills breed on uninhabited islets off the western coast of the Korean Peninsula, making South Korea central to the species’ survival.10Journal of Asia-Pacific Biodiversity. Breeding and wintering home ranges of the black-faced spoonbill Platalea minor GPS tracking of individual birds has revealed that they use relatively small home ranges during the post-fledging stage before undertaking long migrations to wintering sites scattered across East and Southeast Asia.
The Demilitarized Zone as Accidental Refuge
The strip of land separating North and South Korea has been uninhabited and largely untouched by human activity since the Korean War armistice in 1953. Over the decades, the Demilitarized Zone has become an unintentional nature reserve, allowing damaged forests to regenerate and ancient farmland to revert to a wild state. Researchers have described it as containing the last vestiges of Korea’s original natural heritage.11Science. Preserving Biodiversity in Korea’s Demilitarized Zone
The DMZ’s ecological value is most visible in winter, when endangered cranes arrive to feed in the agricultural buffer zones along its edges. Red-crowned cranes and white-naped cranes, both globally threatened, winter in the Cheolwon plain within the DMZ corridor. Field studies have documented how these two species interact on shared foraging grounds: the larger red-crowned crane dominates the white-naped crane in aggressive encounters and actually increases its own foraging activity when the smaller species is nearby, apparently benefiting from scrounging opportunities.12Ecological Research. Effect of heterospecifics on foraging of endangered red‐crowned and white‐naped cranes in the Korean Demilitarized Zone Both species strongly prefer unplowed rice fields for feeding over plowed ones, a detail that matters for conservation planning in the agricultural areas surrounding the DMZ.13Biological Conservation. Winter foraging of threatened cranes in the Demilitarized Zone of Korea: Behavioral evidence for the conservation importance of unplowed rice fields
The irony of a militarized border becoming one of the peninsula’s richest wildlife corridors is not lost on ecologists. Any future political changes to the DMZ, whether reunification or partial development, would immediately put this habitat at risk. Conservation groups have long argued for a formal transboundary peace park, but geopolitical realities have kept the idea in limbo.
Mammals and the Return of the Bear
South Korea’s mammal fauna has been severely altered by centuries of hunting, habitat conversion, and war. The most culturally resonant loss is the Siberian tiger. Tigers were once widespread across the Korean Peninsula and loomed large in Korean folklore, art, and national identity. During the period of Japanese colonial rule from 1910 to 1945, Korean nationalists reimagined the tiger as a symbol of resistance to imperial domination, but the actual animals continued to decline through ongoing hunting and habitat destruction, disappearing from the peninsula entirely by the mid-twentieth century.14Environmental History. Tigers—Real and Imagined—in Korea’s Physical and Cultural Landscape South Korea still uses tiger imagery as a national symbol, including as a mascot for international sporting events, but has no wild tigers.
The Asiatic black bear, however, is being actively brought back. A reintroduction program centered on Jiri Mountain National Park has been running for years, and population modeling suggests the park and its immediate surroundings could support a stable population of roughly 55 to 77 bears depending on resource availability. If bears are allowed to disperse along the broader Sobaek Mountain Range, that number rises to a mean equilibrium of about 230 individuals. Adding a second reintroduction site at Seorak Mountain National Park could push the total across all suitable habitat in the country to well over a thousand bears.15Oryx. Use of a spatially explicit individual-based model to predict population trajectories and habitat connectivity for a reintroduced ursid Whether the country’s fragmented mountain corridors can actually sustain that kind of dispersal remains an open question.
Another mammal quietly persisting in the mountains is the long-tailed goral, a goat-like ungulate classified as Vulnerable. Recent surveys found gorals predominantly in forested mountain habitats between 400 and 800 meters elevation, with nearly all detections occurring in forest cover, split among coniferous, deciduous, and mixed types.16Oryx. Mapping the distribution and predicting the presence of the Vulnerable long-tailed goral Naemorhedus caudatus in South Korea The goral’s reliance on steep, forested terrain has kept it out of direct conflict with urbanization, but it also means its populations are naturally patchy and vulnerable to habitat fragmentation.
Endemic Freshwater Fish and Warming Rivers
South Korea’s rivers are home to a surprisingly rich assemblage of freshwater fish, including dozens of species found nowhere else on Earth. Many of these endemic species occupy narrow ranges within specific river basins, making them acutely sensitive to changes in water temperature and hydrology. Distribution modeling for seven range-restricted endemic species, including bitterlings, loaches, and gudgeons, has shown that projections at broad geographic scales can be misleading. Some species appear to gain suitable habitat at a watershed scale under future climate scenarios, but when analysts zoom in to the specific river basins these fish actually occupy, many face habitat contraction, particularly those adapted to lowland or thermally stable environments.17Global Ecology and Conservation. Projecting habitat changes in range-restricted endemic freshwater fishes: Species- and scale-dependent outcomes
Broader modeling efforts have projected that climate change could push 2 to 20 endemic fish species toward removal from their thermal habitats, with estimated losses of up to about 35 percent of suitable habitat during the 2060s through 2080s depending on the species and river basin in question.18Annales de Limnologie – International Journal of Limnology. Basin-specific effect of global warming on endemic riverine fish in Korea Some species projections are even grimmer: five particular endemic species have been identified as having a high probability of extinction in their respective sub-watersheds by the 2080s under climate-change scenarios.19Ecological Informatics. Predicting potential impacts of climate change on freshwater fish in Korea The general pattern across studies is one of poleward and upward range shifts, but for species already confined to small streams in specific basins, there may simply be no cooler water left to shift into.
Amphibians and the Chytrid Puzzle
The chytrid fungus Batrachochytrium dendrobatidis, or Bd, has devastated amphibian populations on multiple continents, driving dozens of species to extinction. South Korea, however, tells a different story. Surveys across the country have found the fungus widely present, with infection rates ranging from about 12 to 48 percent across 11 of 17 native species tested.20PubMed. Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians Yet Korean amphibians show no signs of the mass die-offs seen elsewhere. The fungal strains in Korea are highly diversified and appear to be long-established endemics rather than recent arrivals.
Experimental infection studies have demonstrated why Korean frogs survive. When three Korean species, including the oriental fire-bellied toad and a native tree frog, were inoculated with both the Korean-endemic Bd lineage and the globally devastating lineage responsible for mass die-offs elsewhere, the Korean frogs rapidly cleared themselves of infection regardless of which strain they were exposed to, surviving with no apparent ill effects. By contrast, an Australian tree frog species known to lack resistance suffered progressive disease and widespread mortality from both lineages. The Korean-endemic Bd strain actually caused faster disease progression in the susceptible Australian species than the globally pandemic strain did, suggesting the ancestral Asian lineage has not mellowed with age; rather, Korean amphibians have evolved robust immune defenses through long coexistence with a hypervirulent pathogen.21PubMed Central. Ancestral chytrid pathogen remains hypervirulent following its long coevolution with amphibian hosts This makes the Korean Peninsula a valuable natural laboratory for understanding how amphibian populations can coexist with a pathogen that has proven catastrophic elsewhere.
Jeju Island at the Subtropical Edge
Jeju Island, off South Korea’s southern coast, sits in a temperate-to-subtropical transition zone that gives it ecological characteristics unlike anywhere else in the country. The volcanic island rises to the 1,950-meter summit of Hallasan, creating an unusually steep elevational gradient from coastal subtropical vegetation to the same Korean fir forests found on the mainland’s highest peaks. Around the island’s coastline, marine habitats have been visibly shifting: communities that were once dominated by macroalgae are gradually transitioning to hard coral dominance, a change associated with warming sea temperatures.22Frontiers in Marine Science. Environmental impact on marginal coastal benthic communities within the Jeju Island, South Korea temperate transition zone
On land, Jeju hosts the Gotjawal lava forests, a distinctive habitat formed on rough volcanic terrain where tree roots weave through porous basalt. Climate change is shifting the canopy composition of these forests from deciduous to evergreen broadleaved species, with cascading consequences for the understory. Two rare plants found in Gotjawal, Maesa japonica and Daphne jejudoensis, both depend on the light conditions created by a deciduous canopy that lets winter and spring sunlight through. Experiments showed both species grew significantly faster under brighter conditions than under the heavy shade of their current forest floor. As the canopy shifts toward denser, year-round evergreen cover, the reduced light threatens the photosynthetic rates these species need to persist.23Journal for Nature Conservation. Sustainability of the endangered species Maesa japonica and Daphne jejudoensis in Gotjawal forest, Jeju Island
Traditional Village Groves
Not all of South Korea’s ecologically valuable habitats are in national parks or remote mountains. Throughout rural Korea, traditional village groves known as Maeulsoop have persisted for centuries as communal forest commons. These small patches of old forest, maintained by villages for cultural, spiritual, and practical reasons, once served as windbreaks, flood barriers, and gathering places. Research examining two dozen of these groves in Namwon City found that larger groves still function as windbreaks or flood banks and are more ecologically resilient than smaller ones.24Forest Policy and Economics. Factors influencing sustainability of traditional village groves (Maeulsoop) in Korea As rural populations decline and villages empty out, many of these groves face neglect or conversion. They represent a form of traditional ecological management that predates modern conservation by centuries, and their loss would erase both cultural heritage and locally significant habitat.
Invasive Freshwater Fish
While endemic species face climate-driven contraction, non-native freshwater fish have been expanding their foothold in South Korean rivers since the 1950s. A risk screening of 43 non-native fish species found that roughly 61 percent posed a high to very high risk of invasiveness. Seven species, including black bullhead, North African catfish, green sunfish, and Chinese sleeper, ranked as very high risk under both current and projected future climate conditions.25Fisheries Management and Ecology. Quantifying Invasiveness Risk of Non‐Native Freshwater Fishes in South Korea Under a Changing Climate As water temperatures rise and thermal barriers shift, the overlap between invasive-friendly conditions and the ranges of temperature-sensitive endemics is likely to grow. This double pressure, warming water from above and competitive or predatory invasives from below in the food web, makes the outlook for South Korea’s unique freshwater fish fauna especially precarious.
Island Ecosystems and Insect Diversity
South Korea’s offshore islands add another layer of biodiversity to the national inventory. Ulleungdo, a volcanic island in the East Sea, hosts roughly 40 plant species endemic to the island alone, along with colonies of rare trees that are scarce on the mainland. The primeval forest atop Seonginbong peak, designated a natural monument, was surveyed using multiple collection methods and yielded insects spanning 11 orders and 113 families, an indication of the habitat’s richness even within a relatively small area.26ScienceDirect. Insect fauna of Seonginbong in Ulleungdo, Korea Islands like Ulleungdo serve as evolutionary laboratories where isolation has produced unique lineages, but their small populations and restricted areas make them inherently vulnerable to disturbance, invasive species, and climate shifts that mainland populations might absorb more easily.