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). An ecotone may appear on the ground as a gradual blending of the two communities across a broad area, or it may manifest itself as a sharp boundary line.
The word ecotone was coined from a combination of eco(logy) plus -tone, from the Greek tonos or tension – in other words, a place where ecologies are in tension.
From Wikipedia 9/29/16
One of my favorite observations while a Teacher in Residence at the University of New Hampshire was…