Assessing the expansion of suitable locations for avocado cultivation due to climate change in Japan and its suitability as a substitute for satsuma mandarins

Abstract

　It is predicted that climate change will make the cultivation of satsuma mandarins more challenging unless adaptation measures can be implemented in current production areas, although changing conditions may favor the cultivation of subtropical fruit trees such as avocado. Therefore, we assessed suitable locations for the future cultivation of both tree species in Japan and the potential of avocado as a substitute for satsuma mandarin. Suitable locations were determined using the annual mean (satsuma mandarin) and minimum (both species) temperatures calculated from the projected temperatures based on two global climate models (MRI-ESM2-0 and MIROC6) under three shared socioeconomic pathways (SSP). Suitable locations for satsuma mandarins were predicted to move northward until the mid-21st century under SSP1-RCP2.6 or until the end of the 21st century under SSP2-RCP4.5 and SSP5-RCP8.5. Among the suitable locations for satsuma mandarins for 1990-2009, the percentage that remained suitable for 2080-2099 varied depending on the SSP, ranging from 0% (SSP5-RCP8.5) to approximately 80% (SSP1-RCP2.6). This highlights the substantial impact of climate change mitigation measures on current satsuma mandarin production areas. Suitable locations for avocados were projected to certainly expand definitely in the future, regardless of the SSP, and many of the suitable locations for satsuma mandarins for 1990-2009 will become suitable for avocados for 2040-2059. Because temperature conditions are suitable for avocado cultivation in most locations that will become too warm for satsuma mandarin production in the future among the suitable locations for satsuma mandarin for 1990-2009, replanting from satsuma mandarins to avocados is an adaptation option in current production areas. Although adaptation measures using cultivation techniques and high-temperature-tolerant cultivars are likely to become less effective as climate change progresses, replanting to avocados was shown to be an effective alternative, at least until the end of the 21st century.