01Why a club
Green plus détente
The club's name joins two words: green, meaning ecology and the protection of living things, and détente, the French word for the easing of tension once used for US–Soviet relations. The aim was twofold: record and study the DMZ's ecology so its value is preserved, and lay groundwork for inter-Korean environmental cooperation that could support peace. The DMZ, closed since the 1953 armistice, has seen almost no pollution or development, so it now shelters first-grade-water fish and many endangered plants and animals. Wonjun planned the club in January 2024 and launched it in March.
- Historical view: the armistice of July 27, 1953
- Military view: minimizing clashes between the two armies
- Political view: a reminder to the world of tension on the peninsula
- Environmental view: a unique and important ecosystem
022024 · Wetlands and dumbeong
Where the Imjin meets the Han
The first surveys focused on water. Inside the Paju civilian-control zone, where the Imjin and Han rivers meet near the west coast, the team compared plants of ordinary wetlands with those of the DMZ's mixed ecosystem and studied how habitat shapes vegetation. They then explored dumbeong, small traditional farm ponds that have returned to nature through succession. Classifying four pond types (spring-fed, still-water, flowing, and still-water spring-fed), they found plant species and individual counts fell in that order, and looked at sunlight, humidity, pH, dissolved oxygen and organic matter as causes. They also recorded IUCN Red List plants such as sweet flag, Manchurian birthwort and Asian milkweed vine.
- Wetland functions: water purification, biodiversity, disaster-risk reduction
- Dumbeong functions: farm water supply, purification, climate regulation
- Saemtong dumbeong inside the Paju civilian-control zone
032024 · Endangered life and forests
A forest that grew back by itself
The DMZ area holds 6,373 species and 42.7% of Korea's endangered species. The team photographed animals such as the fire-bellied toad, a grass lizard and toad tadpoles, and examined threats like shifting vegetation and hunting by outside animals. In the Noesang-ri forest of the Paju DMZ, forest cover had recovered on its own from 51% to 60% once people stopped entering. Grassland held plants like columbine, while forest held species such as Dioscorea and Carex. The conclusion: stabilizing habitats and removing threats protects biodiversity more effectively than breeding individual species.
- Quadrats used to count individuals and estimate cover
- Uneven humidity, sunlight and seed spread explained differences between quadrats
- Native plants such as columbine and Sedum kamtschaticum proposed for forest restoration
042024 · Tools and campaigns
Building our own instruments
Because specimens could not leave the DMZ, the team needed ways to measure on their own terms. They coded and built two water meters, one based on a TDS (total dissolved solids) sensor and one on electrical conductivity. In parallel they held four school campaigns, two community campaigns and 18 study sessions, ran a public DMZ promotion booth with posters, EM mud balls, photographs and mind maps, held a joint campaign with climate experts, and presented the 2024 Youth DMZ Ecological Value Declaration. The year closed with an idea proposal to the Gapyeong County Office, which completed its internal review.
- EM mud-ball making and throwing for residents
- Mind maps of land ecosystems and climate-crisis impacts
- Research report, operations report and Green Détente declaration
052025 · What breaks the corridor
Invaders, feral predators and fire
The DMZ works as an ecological corridor linking the Baekdudaegan mountain range with the lower Han and Imjin rivers, which is why long-tailed goral, otter and leopard cat survive there. In 2025 the club asked what is severing that continuity. Bur cucumber, common ragweed and giant ragweed are spreading along military roads, streams and the Han estuary. Feral dogs now hunt water deer and roe deer, and stray cats prey on snakes and amphibians. Satellite comparisons of a site burned on April 10–11, 2022 showed far more damage than official statistics suggested, with multilayered forest thinning into grass.
- Bur cucumber smothers native plants and blocks photosynthesis
- Feral dogs and cats should be monitored as potential disturbance species
- Fire data from NASA FIRMS; imagery from Google Earth (2018) and USGS (2025)
062025 · Out with residents
Cleanup as an experiment
From March 7 to July 17, 2025, under an official cooperation letter from Gapyeong County, the club worked two river sites in Sinchon-ri, Seorak-myeon: one near Hanyang Bridge and one near the Seorak bus terminal. They sampled soil and water, threw EM mud balls with residents, measured dissolved oxygen, pH and turbidity again and again, and collected trash, styrofoam, organic waste and sediment by plogging. The lesson they drew: environmental problems should not rely on emotional appeal alone. Pairing volunteer cleanup with repeated measurement turns it into an experiment, and data makes the solution sustainable.
- 5 campaigns and cleanups, one a month
- 10 study sessions
- Campaign posters for residents
072025 · The lab
Does EM and calcium carbonate actually work?
Security rules made sampling inside the DMZ difficult, so the team compared river water from near the DMZ in Cheorwon with water from Seorak, Gapyeong. EM is a blend of about 80 beneficial microbes, including lactic acid bacteria, photosynthetic bacteria and yeasts, that break down organic matter and suppress odor. Calcium carbonate adsorbs pollutants, precipitates heavy metals and neutralizes acidity. Over eight experiments from March to July, samples were treated for two weeks and measured for odor, turbidity, suspended solids, pH, COD, DO, total nitrogen and phosphate. A second test checked whether the mix removes copper ions from water.
- Treated sample: 250 mL river water + 2 mL EM solution + 3 g CaCO3
- Odor measured with an MQ7 gas sensor on an Arduino Uno
- Turbidity measured as absorbance at 650 nm on a UV/Vis spectrophotometer
082025 · Results
Clear water can hide dirty chemistry
The two rivers told opposite stories. Seorak water was visibly cloudy; after treatment its turbidity fell 97% while COD stayed at 6 ppm. Cheorwon water looked clear, yet its COD of 13.5 ppm ranked as very poor; treatment brought it to 8 ppm, a 41% drop. Odor readings fell 9% and 11%, pH moved from 7 to 8 in both, and DO barely changed. Nitrogen and phosphate rose instead of falling, which the team traced to their filter paper letting EM bacteria through; they concluded a membrane filter with pores of 0.2 μm or smaller is needed. In the copper test, the treated solution produced 63.3% less precipitate.
- Limits: short experiment period, restricted DMZ sampling, narrow set of indicators
- Next: seasonal, long-term and multi-site repeats
09Conclusions
Prevent, respond, restore
The club closed 2025 with proposals. For invasive plants: physical removal once they are clearly visible, cover planting to block spread, and long-term cutting of seed pathways. For invasive animals: direct capture, strengthening native predators such as otter and leopard cat, and monitoring feral dogs and cats. For wildfire: minimize military fire sources, watch high-risk zones, set up drone-based real-time fire detection and early-suppression manuals, and run tailored restoration for burned land. Locally, they plan to widen resident programs such as EM mud-ball sessions and share results at community events, so small acts of volunteering are backed by scientific evidence.
- 2024 ideas still on the list: mammal, migratory bird and overwintering-species surveys
- A DMZ ecosystem app and photo exhibition
- Policy proposals to DMZ-related agencies
