Ecotone

An ecotone is the transition zone between two diverse ecosystems. These ecotones are very important because this is where two communities meet and integrate. This intermixing of two communities give rise to incredibly rich biodiversity where species of both the ecosystems can be found as well as certain species which are unique to the ecotone. A mangrove forest is a very common example of an ecotone which is formed at the junction of a marine ecosystem and a terrestrial one.

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The geographical spread of an ecotone may be narrow, as it is in a riverbank (aquatic and terrestrial) or wide as it is in grasslands between deserts and forests.

Due to the interaction of communities belonging to different ecosystems, the ecotone is a zone of constant tension and development. And the ecotone is generally characterised by features of both the adjoining ecosystems, albeit in a moderate way. A grassland may receive moderate rainfall, as opposed to the copious amounts received by the rainforests. The same grasslands may have a moderate temperature, unlike the adjoining desert.

Due to these moderate conditions, the population density, as well as the diversity of an ecotone, is generally higher than both its adjoining communities.

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This leads to an interesting effect called Edge Effect. The Edge Effect is observed when the number of species and the population density of some species is greater in the ecotones than it is in their original ecosystem. These species are call edge species. For example, the population of birds is greater in the ecotone between forests and deserts than it is in either of them.