Ecotone
An ecotone is defined as a zone of junction between two or more diverse ecosystems. It represents a transition area where the characteristics of adjacent ecosystems mix.
For example:
- Mangrove forests represent an ecotone between the marine and terrestrial ecosystems.
- Other examples include grasslands, estuaries, and river banks, which form transitional areas between two distinct ecological communities.
Characteristics of Ecotone
The ecotone exhibits some unique features:
- It may be narrow or wide, depending on the extent of transition between ecosystems.
- It contains intermediate conditions, combining features of the adjoining ecosystems, making it a zone of tension.
- The species composition shows a progressive increase of incoming community species and a simultaneous decrease of outgoing community species, forming a linear transition.
- A well-developed ecotone may even host some unique organisms, not found in the adjacent ecosystems.
- Often, the number of species and the population density of some species is greater in the ecotone than in either adjoining community — a phenomenon known as the edge effect.
Edge Effect and Edge Species
- The edge effect refers to the tendency of certain species to occur more abundantly in ecotones compared to the core areas of either ecosystem. The species that are most abundant or primarily found in the ecotone are called edge species.
For example:
- In terrestrial ecosystems, the density of birds is often higher in the mixed habitats of the ecotone between a forest and a desert than in the forest or desert alone.