Changes in locations suitable for satsuma mandarin and tankan cultivation due to global warming in Japan

Satsuma mandarin, a temperate citrus species, is the leading fruit tree species in Japan, and the changes in the suitable locations due to future global warming have been already predicted. To offer satsuma mandarin producers information for making a decision of replanting, we simulated future locations suitable for the cultivation of satsuma mandarin and tankan, a subtropical citrus species, considering the uncertainty created by variation in climatic predictions. Simulations were done on the basis of future annual mean and minimum temperatures evaluated by six general circulation models under the SRES-A1B GHG emission scenario. The results indicated that the locations suitable for satsuma mandarin would gradually expand northward and inland. However, the judgment of locations suitable or unsuitable depended on the GCMs in many regions during 2041-2060 and few regions were classified by all GCMs as suitable during 2061-2080. The locations suitable for tankan will expand northward, however, a few suitable locations will be the inland of Japan during 2021-2040. Therefore, if increased global warming causes declines in satsuma mandarin production, then tankan could be produced as a substitute in the coastal areas of current satsuma mandarin-producing regions. However, it will be difficult to produce tankan in the inland areas of these regions due to cold injury in fruits for the next few decades.