This is thought to be caused by the blooming of Japanese cedar trees in high altitude areas, which were planted slightly later and developed more slowly, later than the blooming of trees located in flat areas.
これは、やや遅れて植林されたり、成長が遅れていた標高の高い地域のスギの開花が、平地での開花に引き続いておこるためと考えられている。