Alien flora of the Korean Peninsula

The Korean Peninsula has been divided into the countries of North and South Korea since 1948. This adoption of different political and socio-economic regimes has significantly changed economic activity and international exchange by those nations, thus affecting the introduction of alien plants. Our study objective was to provide a comprehensive, up-to-date inventory of the alien flora on the Korean Peninsula and to analyse how the partitioning between North and South Korea has influenced the numbers and status of those alien plants. We identified pre-1876 aliens that were brought to the Korean Peninsula before 1876, when Korea opened up to foreign countries, and also determined the post-1876 aliens that were introduced after 1876. Plants in the latter group were further classified into those that arrived before the outbreak of the Korean War in 1950 (1876–1950 aliens) and those introduced since then (post-1950 aliens). We investigated the regions of origin, family compositions, and invasion status of those alien taxa. In total, 504 alien taxa were identified, with 102 taxa being pre-1876 and 117 being 1876–1950 aliens. After the Korean War, the number of alien plants in South Korea more than doubled (276 taxa), whereas the number reported for North Korea was considerably lower (33 taxa). This might be due to enhanced economic activity and a larger human population in South Korea. Climatic differences as well as variations in the recording intensity for alien flora between North and South Korea may also have contributed to the large contrast in numbers of new alien species recorded during the last decades. Coordinated measures between the two nations are necessary if the spread of invasive alien plants onto the Korean Peninsula is to be reduced.