بوم‌مرز

thumb|Reed beds are a common form of lakeside ecotone. The beds tend to accumulate organic matter which is then colonised by trees, forcing the reeds further into the lake. An ecotone is a transitional area between two plant communities, where these meet and integrate. Examples include areas between grassland and forest, estuary and lagoon, and freshwater and sea water. An ecotone 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