What Are Ecotones?

An ecotone is a transition area between two different ecosystems or plant communities. This could be a boundary between a forest and a grassland, a marshland between a river and its bank, or an estuary where freshwater mixes with saltwater. Ecotones can be wide or narrow, and they are often rich in species due to the influence of both adjoining ecosystems123456.

Key Characteristics of Ecotones

• Transitional Nature: Ecotones are zones where two communities integrate, leading to a mixture of species from both sides.

• High Biodiversity: Due to the “edge effect,” ecotones typically support a greater variety of species than either neighboring ecosystem.

• Species Interactions: The overlap of habitats fosters increased competition, predation, and symbiosis.

• Environmental Gradients: Ecotones often feature gradients in light, moisture, soil type, and other environmental factors, creating diverse microhabitats.

Examples of Ecotones

• Intertidal zones (between land and sea)

• Estuaries (between freshwater and saltwater)

• Marshlands (between dry land and wetlands)

• Mountain foothills (between plains and mountains)

• Grassland-forest boundaries

Evaluating the Statements

Let’s analyze each statement about ecotones:

(1) Intertidal zones and estuaries are two examples of ecotones

Correct.
Both intertidal zones and estuaries are classic examples of ecotones, as they represent transitional areas between distinct ecosystems and support high biodiversity1245.

(2) They are transitional areas of vegetation between two different plant communities

Correct.
By definition, ecotones are transitional zones between two different plant (or ecological) communities, where characteristics of both are present1345.

(3) Populations in ecotones are potentially pre-adapted to changing environment.

Correct.
Because ecotones experience variable and sometimes fluctuating environmental conditions, species living in these areas often exhibit adaptations that allow them to cope with change5.

(4) They harbour only K-selected species that can survive in changing habitats

NOT CORRECT.
This statement is incorrect. Ecotones do not exclusively harbor K-selected species. In fact, ecotones support a mix of species from both adjoining ecosystems, including both r-selected (opportunistic, fast-reproducing) and K-selected (stable, competitive) species. The diversity and dynamic nature of ecotones mean that a wide variety of life strategies can be successful, not just those of K-selected species125. The edge effect in ecotones often leads to the presence of both generalist and specialist species, as well as unique species adapted specifically to the transitional environment.

Conclusion

Among the given statements, the one that is NOT correct with respect to ecotones is:

(4) They harbour only K-selected species that can survive in changing habitats

Ecotones are rich in biodiversity and support a wide range of species with different ecological strategies, not just K-selected species. This diversity is one of the defining features of ecotones and is central to their ecological importance.