Global Warming Leading to Phenological Responses in the Process of Urbanization, South Korea

Current studies are either region-limited, sole-species, or have short researching periods; so, studies about various species are necessary throughout South Korea. In this study, trends of changes in the budding and flowering dates of spring plants by climate factors served to explore the process of urbanization. Four common species, such as Forsythia koreana (forsythia), Rhododendron mucronulatum (azalea), Prunus yedoensis (Yoshino cherry) and Prunus mume (Japanese apricot), are examined during the period from 1973 to 2008 due to the limitation of recent datasets. Budding of forsythia, azalea, Yoshino cherry and the flowering of Japanese apricot are defined as Type I (inland, of reverse letter ‘L’) and flowering of forsythia, azalea and Yoshino cherry were grouped as Type II (inland and south coastline). Prunus mume budding was different from others, so it was defined as Type III (subtropical climate). The inland phonological response is relatively cold and dry and areas are affected by the Siberian high atmospheric pressure. On the other hand, the south and east coastlines are humid and warm areas even in the winter season due to the southeastern wind. There were advancements for 3.1 days of forsythia, 5.5 days of azalea, 6.5 days of Yoshino cherry and 18.6 days of Japanese apricot during the research period. The greatest changes occurred with respect to the minimum temperature in January and the maximum temperature in February, while the precipitation change was not significant. However, in Type II, the precipitation significantly impacted plant flowering events. Precipitation was the lowest in early spring in South Korea and especially the flowering of plants was impacted by the small amount of precipitation in this region. Additionally, if precipitation after budding was over 1 mm for forsythia and azalea, 2 mm for Yoshino cherry and 7 mm for apricot, flowering occurred in over 80% of the region. South Korea is characterized as having a small amount of land and a high population density in cities. As such, it encounters strong influences due to global warming, as well as urbanization. Seven metropolitan cities and Suwon have populations over 1 million and showed more remarkable phenological events and changes of climate factors than the other regions. Especially in the case of shrubs, the phenological events were delayed in urban areas during this research. In conclusion, climate change, as well as urbanization, serve as strong factors leading to phonological and regional events in the ecosystem.