Native to Japan, Japanese cedar was introduced to the Korea during the Japanese occupation and were planted in warmer areas such as Jeju Island. In the Korean government’s 10-Year Forest Afforestation Plan, which began in 1973, cedar was selected as one of the 10 recommended tree species and became the representative tree of Jeju. Although cedar was chosen as a long-term and timber tree, it was welcomed by the locals because of its fast growth rate, and by the 1980s, the cedar forest had become the largest artificial forest on Jeju Island. However, around this time, research into pollen allergies began to emerge, and a decade later it was confirmed that cedar trees were responsible for severe pollinosis. When cedar’s pollen allergies became a social issue, the ecological threat to native plants was raised in earnest. Despite the controversy surrounding them, Jeju’s cedar forests have created a new landscape that has become very popular with tourists visiting the island. The dual nature of Jeju’s cedar forests—functioning as a valuable economic resource on the one hand, and posing ecological and public health hazards on the other—has prompted a fundamental re-evaluation of government policies focusing on large-scale planting of recommended species. This demonstrates that establishing healthy and resilient forest ecosystems requires the active integration of local community perspectives and scientific expertise.