Ecosystems represent an assemblage of communities that exist at different successional stages. Along the edges of each of the patches are areas called ecotones.
Ecotone is a transitional area of convergence between two diverse ecosystems such as mangroves which represent a transitional zone or junction between terrestrial and marine ecosystems.
Examples of Ecotone: Other examples of such ecotones include estuary which is a transitional zone between freshwater rivers and marine ecosystem, marshland between river and riverbank, grassland between forests at one end and deserts at the other, lagoons etc.
Ecotone and edge effect
Characteristics of Ecotones
- Ecotones represent overlapping boundary regions or junctions where two major terrestrial or aquatic biomes meet.
- They may vary in sizes from being very narrow to quite wide. The transitional zones of ecotones are very clearly cut and marked by distinctiveness in the vegetation.
- Ecotones are found along an ecological gradient. The gradients are created as a result of spatial shifts in elevation, climate, soil, and many other environmental factors. Ecotones are very rich in biodiversity and are known for their species richness.
- They often contain species from each of the overlapping communities as well as some other species that have become adapted specifically for living in these zones and not found in any of the adjoining communities.
- In many cases, the number of species and the population density are greater within the ecotones than in the surrounding communities, a phenomenon known as the edge effect.
- Ecotones are usually very sensitive to climate change as well as humaninduced changes. Such changes in ecotones can cause changes in biodiversity, functioning, structure and species composition of an ecosystem. Ecotones are a very important source of information and insights on the process of evolution.
Formation of Ecotones
- Natural Ecotones: Naturally ecotones can be formed through abiotic factors such as changes in soil composition. Ecotones are very common on mountain ranges due to a wide variety of climatic conditions observed on the slopes of mountains.
- Human interaction: Ecotones can also be formed as a result of human interaction. For example, the transition between areas of forest and cleared land.
Importance of Ecotones
- The Ecotone has the characteristics of the two bordering ecosystem. As a result, it has a very high density of organisms and variety of species can be found in an ecotone.
- They act as a bridge for gene-flow from one community to other and provide habitat to a large number of species.
- Due to these characteristics, ecotones have a very rich and vibrant biodiversity. Therefore, ecotones are areas of a great environmental importance.
- An Ecotone can act as a “buffer-zone” protecting the neighbouring ecosystem from possible environmental damage. For example, Mangrove forests provide a natural buffer against Tsunamis and a wetland could absorb pollutants to prevent them from entering into an estuary.
- Ecotones are very ecologically sensitive areas. They are natural indicators of climate change and its consequences. Thereby, they have been a matter of greater scientific interests.
Edge Effect Definition
What is edge effect? Ecotones are the transitional zone between two diverse ecosystems. Often, these transitional zones have increased variety and population of different plants and animal species. Some of the species in these zones are much greater than either of the bordering communities.
This phenomenon or characteristic of ecotones is known as the “edge effect”. The edge effect in ecology observed mainly due to the contrasting influences of the two bordering ecosystems.