ecotone
n.β Β«An ecotone is a term from the field of ecology. It is a place where landscapes meetβlike field with forest, or grassland with desert. The ecotone is an area of increased richness and diversity where the two communities commingle. Here too are creatures unique to the ecotone…the so-called βedge effect.βΒ» βEcotone: Writing About Place , 2003. (source: Double-Tongued Dictionary)