Evaluation of the potential impacts of climate change on the chilling requirement of apple trees in Lebanon, by the mid and the end of the Twenty-First century

Abstract

Since Apple orchards rely on winter chill for the breaking of their dormancy, increases in the temperature might affect their production. The aim of this study is to evaluate the potential impacts of climate change on the chilling requirements of the apple tree in Lebanon by the mid and the end of the twenty first century. To examine this effect, I investigated the changes in the number of chilling hours ( <7.2 {grave}{aelig}{92}C) in Lebanon using simulations of hourly temperatures during the dormant period. These simulations were produced from the regional climatic model (PRECIS) during the dormant period, at the mid and end of the 21st century, for Beirut. This data was adjusted to the actual elevation of the stations, calibrated using hourly measured temperatures for 2001 at the Gulf of Beirut, and then generated for every 100 m altitude. Results were finally visualized in three maps indicating three studied periods (recent past, mid and end of the 21st century). The average for winter temperatures are expected to increase and the warm extremes are projected to be warmer while the cold extremes are projected to be colder by the mid and the end of the 21st century. The chilling periods appeared not to be vulnerable to the projected temperature increase, and are expected to stay approximately the same with the exception of altitudes ranging between 700 m and 800 m where the chilling hours might increase. As a result of this research, apple farmers can take advantage of the generated maps to plant the suitable variety of trees in its corresponding chilling zone.