Key Characteristics and Significance of Ecotones
Ecotone is known to be a transitional area, which is present between two ecosystems or two different pleasant communities like forest and grassland. They are known to be of great environmental importance as they often contain those species which are not found in the overlapping communities. They are home to many flora and fauna as they have an area transition between two ecosystems and biomes. They may also exist along a broad belt or in a small pocket, such as a forest clearing, where two local communities blend together.
Some of the very known examples of ecotones are marshlands (between dry and wet ecosystems), mangrove forests (between terrestrial and marine ecosystems), grasslands (between desert and forest), and estuaries (between saltwater and freshwater). Mountain ranges can also create ecotones due to the changes in the climatic conditions on the slopes. Ecotone can also be seen in the area where one water body meets with another water body like estuaries and lagoons or at the boundary line between water and land like marshes.
Freshwater and Marine Ecotones
Both of these ecotones are differentiated on the basis of the presence of large plants that rise from the roots attached to the submerged substrate and because of this reason they are found in areas where ample light is available at the bottom of the basin to permit growth.
Characteristics of Ecotones
Some of the major characteristic features of ecotones are discussed below:
A. They can be natural or man-made. Example: agriculture field and forest (it is a man-made one).
B. They may vary in size from narrow to wide.
C. They are known to be zones of tension as they show conditions intermediate to the bordering ecosystems.
D. They may also contain those species which are totally different from those found in the bordering systems.
Importance of Ecotones
Ecotones have so many important roles in the ecosystem, some of them are listed below:
A. Ecotones show greater variation in an organism.
B. They provide a comfortable habitat for different organisms i.e. by providing space for nesting for those animals who roam here and there in search of food or a place for a nest.
C. They act as a bridge or mode of transportation of gene flow from one population to another as they show larger genetic diversity.
D. They offer protections to the bordering of an ecosystem from various damages and that's why they are known to be the buffer zone.
E. Ecotones also show sensitivity toward global climate change. Climatic changes take place because of the shifting of boundaries between ecosystems.
Ecoline
The zone in which there is a continuous change from one ecosystem to another in the absence of a sharp boundary between the two in terms of species composition is called an ecoline.
The flow of an ecoline occurs across the environmental gradient, like gradual change in abiotic factors such as altitude, temperature, salinity, depth, and many more.
Edge Effect – Edge Species
When there is a change in population size or community structure that occurs at the boundary of two habitats then it is known as the edge effect. It is seen that sometimes the population density of some species in the ecotone is higher than any other community and this effect is known to be an edge effect. And edge species are those which occur primarily or most abundantly in the edge zone.
In the case of the terrestrial ecosystem, mainly birds show edge effects. For example, the population density of birds is greater in the ecotone between the forest and the desert.
Formation of Ecotones
When there is any kind of change in the physical environment then, in that case, they may produce sharp boundaries, as an example of the interface between areas of forest and cleared land. Mainly mountain ranges are responsible for the formation of such ecotones as they show a wide variety of climatic conditions experienced on their slope ranges. A terrain acts as an obstructive boundary which provides a boundary between species. The most common example of this condition is seen in Mont Ventoux in France as it acts as a boundary between the flora and fauna of northern and southern France.
FAQs on What is an Ecotone in Biology?
1. What is an ecotone in Biology as per the NCERT syllabus?
In biology, an ecotone is defined as a transitional or boundary zone between two distinct ecosystems. It exhibits characteristics of both adjacent communities. For example, the area where a forest meets a grassland is an ecotone. It is not simply a dividing line but a functional zone of interaction, often containing species from both ecosystems as well as species unique to the ecotone itself.
2. What are the key characteristics of an ecotone?
Ecotones have several distinct characteristics that are important for students to understand:
Transitional Nature: It may have a sharp boundary or be a gradual transition over a larger area.
Species Richness: It often contains a greater number of species and a higher population density than either of the adjoining ecosystems. This phenomenon is known as the edge effect.
Unique Species: Some species, known as edge species, are specifically adapted to and may only be found in the ecotone.
Zone of Tension: It is an area where conditions are not optimal for species from the adjacent ecosystems, creating a unique environmental state.
3. What are some common examples of ecotones?
There are many real-world examples of ecotones that illustrate the concept:
Mangrove Forests: An ecotone between a marine (ocean) and a terrestrial (land) ecosystem.
Estuaries: A transition zone between freshwater (river) and saltwater (sea) ecosystems.
Grasslands: Often form an ecotone between a forest and a desert.
Riverbanks (Riparian zones): Act as an ecotone between the aquatic ecosystem of the river and the terrestrial ecosystem of the land.
4. Why are ecotones considered areas of high ecological importance?
Ecotones are ecologically important primarily because they function as biodiversity hotspots. The overlap of two different habitats means that resources from both communities are available in one area. This abundance and variety of resources can support a wider range of organisms than either single ecosystem could alone. Furthermore, they facilitate gene flow between populations, which can lead to increased genetic diversity and evolution.
5. What is the 'edge effect' in the context of an ecotone?
The edge effect is a key ecological principle observed in ecotones. It refers to the change in population or community structures that occurs at the boundary of two habitats. In most cases, the edge effect results in both a greater number of species (species richness) and a higher population density of some species in the ecotone compared to the neighbouring ecosystems. For example, many bird species thrive in the ecotone between a forest and a field because they can access food from the field and shelter from the forest.
6. How are ecotones formed, both naturally and due to human activities?
Ecotones can be formed through both natural processes and human intervention.
Natural Formation: These arise from significant changes in the physical environment. For example, a mountain range can create sharp climatic differences on its slopes, forming distinct ecotones. A riverbank naturally forms a boundary between aquatic and terrestrial ecosystems.
Human-induced Formation: Human activities often create sharp, abrupt ecotones. A classic example is the boundary created between a forest and a cleared area for agriculture or urban development.
7. How does an ecotone differ from an ecoline?
The main difference lies in the nature of the transition. An ecotone is a distinct zone where two communities meet and integrate, often resulting in a sharp transition and high biodiversity. In contrast, an ecoline (or ecological gradient) represents a gradual and continuous change in environmental conditions and species composition from one ecosystem to another, without a sharp boundary. For example, the gradual change in vegetation as you move up a mountain (altitude gradient) is an ecoline.
8. Can you provide an example of a major ecotone in India?
A prime example of a large-scale ecotone in India is the Sundarbans mangrove forest. This region acts as a critical transition zone between the freshwater ecosystems of the Ganga-Brahmaputra river delta and the saltwater marine ecosystem of the Bay of Bengal. It supports a unique and rich biodiversity, including the Royal Bengal Tiger, which has adapted to this specific brackish water environment.
9. How can studying ecotones help scientists monitor the effects of climate change?
Ecotones are highly sensitive to changes in climate. Because they exist at the boundary of environmental tolerances for many species, even slight shifts in temperature or precipitation can cause the ecotone's boundary to move. Scientists can monitor these shifts over time. For example, if a forest-grassland ecotone boundary is observed to be moving, it can serve as a powerful bio-indicator of regional or global climate change, providing valuable data on how ecosystems are responding to environmental pressures.
10. What is the difference between an ecotone, a niche, and a biome?
These are three distinct ecological concepts that students often confuse:
Ecotone: A transitional area between two biomes or ecosystems. It is a place.
Niche: The specific functional role an organism plays within its ecosystem, including its diet, behaviour, and interactions. It is a role or 'profession'.
Biome: A very large ecological area with a specific climate, soil, and a distinct community of plants and animals (e.g., tropical rainforest, desert, or tundra). An ecotone is the boundary between two such biomes.
