Shin Joon Hwan, an ecologist, walked along a road lined with cherry trees on the verge of blooming last week, examining the fine hairs around their dark red buds.

The flowers in Gyeongju, South Korea, an ancient capital, belong to a common Japanese variety called the Yoshino, or Tokyo cherry. Shin’s advocacy group wants to replace those trees with a kind that it insists is native to South Korea, called the king cherry.

"These are Japanese trees that are growing here, in the land of our ancestors,” said Shin, 67, a former director of South Korea’s national arboretum.