ecotone       
noun [ C ]  environment specialized uk/ˈiː.kəʊ.təʊn/ us/ˈiː.koʊ.toʊn/
 群落交错区,生态过渡带
a region where one type of habitat or natural environment meets another
  The ecotone between forest and pasture was overgrown with lantana plants. 森林与牧场之间的交错带长满了马缨丹。 
 the tropical/subtropical ecotone  热带/亚热带交错带