Forest Biologist Janice Cooke has studied the invasion of Mountain Pine beetles for decades.

森林生物学家Janice Cooke数十年来一直在研究山松甲虫的入侵。

Like, thanks to milder winters, the mountain pine beetle has been expanding its range and killing vast swaths of trees in western North America.

就像， 由于冬季较温和，山松甲虫一直在扩大其范围并杀死北美西部的大片树木。