Predicted Effects of Climate Change on Winter Chill Accumulation by Temperate Trees in South Korea

Abstract

This study was conducted to understand the characteristics of winter chill accumulation in South Korea and to predict its fluctuations due to global climate change. Using climate data for 30 regions and previously established models, we estimated winter chill accumulation for those regions and predicted future changes. The temperature range from 0-7.2 degrees C is considered effective for breaking endodormancy, so an average of 1750 chilling hours was supplied per winter between 1999 and 2015. The 30 study regions were divided into five groups based on temperature distribution. Groups 1 and 2 had fewer and more than 830 annual hours at temperatures of 0-3.6 degrees C, respectively. Groups 3, 4, and 5 had 950-1310, 1310-1515, and more than 1515 hours, respectively, at temperatures below 0 degrees C. The number of hours the groups was exposed to the effective temperature range for breaking endodormancy under the projected elevated temperature conditions decreased from group 5 to group 1; the loss of effective hours was in the same order. As a result, winter chill accumulation abruptly decreased from group 5 to group 1 under elevated climatic temperature conditions. The delay in the start of winter chill accumulation increased from groups 4 and 5 to group 1, and the end came earlier in the same order; groups 4 and S showed very similar changes at the start and end of chill accumulation. Under elevated temperature conditions, chilling accumulation is expected to start later and end earlier in all regions. These changes will be accelerated with a greater rise in regional temperatures, and elevated temperatures will lengthen the endodormancy of woody plants, but shorten the period of chilling accumulation. The results of this study can be used as fundamental data to establish plans for responses to climate change such as the selection and renewal of cultivars.