Transitional land zone between forests and grasslands, e.g

• Transitional land zone
• Transition area between plant communities
• Transition area from deciduous to evergreen, e.g.
• Biome border
• Environmental transition area
• Plant transition zone
• Ecological transition area

Wiktionary Word definitions in Wiktionary
n. a transition area between two adjacent ecological communities (ecosystems).

Wikipedia Word definitions in Wikipedia
An ecotone is a transition area between two biomes . It is where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems ...