Gim Hyeon-Ju, Ho Chang-Hoi, Kim Jinwon, Lee Eun Ju
School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea.
Climate Research Division, National Institute of Meteorological Sciences, Seogwipo-si, Korea.
PLoS One. 2018 Feb 7;13(2):e0191428. doi: 10.1371/journal.pone.0191428. eCollection 2018.
Regional warming, owing to urbanization, leads to earlier spring phenological events and may expose plants to hard freeze damage. This study examined the influence of urbanization on the risk of frost damage to spring flowers in South Korea from 1973 to 2015. For the analysis period, we categorized 25 cities into two groups: those showing rapid population growth (rPG) ≥ 200,000, including 13 cities, and those showing no or decreased population growth (nPG), including 12 cities. We then investigated the time from the last frost dates (LFDs) in spring to the first flowering dates (FFDs) for each group. The rPG group experienced significant spring warming of 0.47°C per decade, resulting in earlier LFDs and FFDs. For this group, the advancement of LFD was more rapid than that of FFD, and the days between these two dates increased from 0.42 to 0.47 days per decade, implying a reduced risk of frost damage. Spring warming and the advancement of FFDs and LFDs were relatively small for the nPG group, and the LFDs were rather delayed. Consequently, the days between LFDs and FFDs were reduced from -1.05 to -1.67 days per decade, indicating an increased risk of frost damage. The contrasting changes in the frost-damage risk between the two city groups can be attributed to distinct urban warming at night, which makes the LFDs substantially earlier in the rPG group. Therefore, this study suggests that the warming associated with urbanization may lessen the risk of spring frost damage to plants in rapidly growing urban areas.
由于城市化导致的区域变暖，会使春季物候事件提前发生，并可能使植物遭受严重冻害。本研究调查了1973年至2015年城市化对韩国春季花卉霜冻危害风险的影响。在分析期内，我们将25个城市分为两组：人口快速增长（rPG）≥20万的城市，共13个；人口无增长或减少（nPG）的城市，共12个。然后，我们调查了每组从春季最后一次霜冻日期（LFD）到首次开花日期（FFD）的时间。rPG组春季每十年显著变暖0.47°C，导致LFD和FFD提前。对于该组，LFD的提前速度比FFD更快，这两个日期之间的天数每十年从0.42天增加到0.47天，意味着霜冻危害风险降低。nPG组的春季变暖和FFD及LFD的提前幅度相对较小，且LFD相当滞后。因此，LFD和FFD之间的天数每十年从-1.05天减少到-1.67天，表明霜冻危害风险增加。两组城市霜冻危害风险的对比变化可归因于夜间明显不同的城市变暖情况，这使得rPG组的LFD大幅提前。所以，本研究表明，与城市化相关的变暖可能会降低快速发展的城市地区植物春季霜冻危害的风险。
