Table of Contents
- An ecotone is a zone of junction or a transition area between two biomes [diverse ecosystems]. It is where two communities meet and integrate.
- For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are grassland (between forest and desert), estuary (between fresh water and salt water) and river bank or marsh land (between dry and wet).
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Characteristics of Ecotone
- It may be narrow (between grassland and forest) or wide (between forest and desert).
- As it is a zone of transition, it has conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension.
- Usually, the number and the population density of the species of an outgoing community decreases as we move away from community or ecosystem.
- A well-developed ecotones contain some organisms which are entirely different from that of the adjoining communities.
Edge Effect – Edge Species
- In ecology, edge effects refer to the changes in population or community structures that occur at the boundary of two habitats (ecotone).
- Sometimes the number of species and the population density of some of the species in the ecotone is much greater than either community. This is called edge effect.
- The organisms which occur primarily or most abundantly in this zone are known as edge species.
- In the terrestrial ecosystems edge effect is especially applicable to birds. For example the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert.
- Niche refers to the unique functional role and position of a species in its habitat or ecosystem.
- In nature, many species occupy the same habitat but they perform different functions.
- The functional characteristics of a species in its habitat is referred to as “niche” in that common habitat.
- Habitat of a species is like its ‘address’ (i.e. where it lives) whereas niche can be thought of as its “profession” (i.e. activities and responses specific to the species).
- A niche is unique for a species while many species share the habitat. No two species in a habitat can have the same niche. This is because of the competition with one another until one is displaced.
- For example, a large number of different species of insects may be pests of the same plant but they can co-exist as they feed on different parts of the same plant.
- A species’ niche includes all of its interactions with the biotic and abiotic factors of its environment [habitat niche – where it lives, food niche – what is eats or decomposes & what species it competes with, reproductive niche – how and when it reproduces, physical & chemical niche – temperature, land shape, land slope, humidity & other requirement].
- An ecological niche describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey).
- Niche plays an important role in conservation of organisms. If we have to conserve species in its native habitat we should have knowledge about the niche requirements of the species and should ensure that all requirements of its niche are fulfilled.
Q4. Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms?
- Ecological niche
- Home range
Answer: b) Niche
- Ecotone – zone of transition between two ecosystems. E.g. grasslands, mangroves etc.
- Habitat – surroundings in which an organism lives (home).
- Home Range – Ahome range is the area in which an animal lives and moves on a daily or periodic basis (a little bigger than habitat – home → office → home).