Ecotones

Ecotones, examples ,characteristic features, edge effect, ecoclines

1. ECOTONES Presented By : Tuba Tahir

2. What is an ECOTONE? The word Ecotone was coined by  Alfred Russel Wallace , in 1859 who first observed the abrupt boundary between two biomes. This word is formed as a combination of Ecology plus tone, from the  Greek  tonos or tension, which means a place where ecologies are in Tension. We can simply say that an ecotone is an area that acts as a boundary or a transition between two ecosystems.

3. Definition : In simple words, An ecotone is a zone of junction or a transition area between two biomes. An ecotone can be defined as a transition area where ecological communities, ecosystems, or biotic regions coincide and where two communities meet and integrate . Ecotones can be defined in various ways but in essence they are dynamic boundaries and transitional areas between two very distinct ecological habitats containing different communities and physicochemical features.

4. Examples: Examples of ecotones include marshlands (between dry and wet ecosystems), mangrove forests (between terrestrial and marine ecosystems). The mangrove forest is shown below.

5. Other examples includes Grasslands (between desert and forest), and estuaries (between saltwater and freshwater)such as, Mountain ranges can also create ecotones due to the changes in the climatic conditions on the slopes.

6. Features of Ecotones: It may be narrow or wide. Ecotone may be local (the zone between a field and forest). Ecotone can also be regional (the transition between forest and grassland  ecosystem). An ecotone may appear on the ground as a gradual blending of the two communities across a broad area .

7. Ecotone may manifest itself as a sharp boundary line. This could be, for example, an area of marshland between a river and the riverbank. An ecotone is a zone of tension (as it has conditions intermediate to the bordering ecosystems). It could contain species that are entirely different from those found in the bordering systems.

8. Formation of Ecotones: Changes in the physical environment may produce a sharp  boundary , as in the example of the interface between areas of  forest  and  cleared land . An Ecotone can be formed naturally through abiotic factors such as changes in soil composition but can also be created through the result of human interaction. Mountain ranges often create ecotones, due to the wide variety of climatic conditions experienced on their  slopes . They may also provide a boundary between species due to the obstructive nature of their  terrain . 

9. Mont Ventoux  in  France  is a good example of ecotone, marking the boundary between the  flora  and  fauna  of northern and  southern France . Most  wetlands are ecotones. The spatial variation of ecotones often form due to disturbances, creating patches that separate patches of vegetation. Different intensity of disturbances can cause landslides, land shifts, or movement of sediment that can create the vegetation patches and ecotones.

10. Biodiversity in Ecotones: As the area of ecotone is inevitably influenced by the two bordering ecosystems,  therefore there is a higher density of organisms and variety of species  in an ecotone. The ecotones (junction zones) often contain species of each of the overlapping communities as well as some species that have become adapted specifically for living in these zones. Some organisms need a transitional area for activities such as  courtships , nesting, or foraging for food.

11. Edge effect: Edge effect refers to the changes in population or community structures that occur at the boundary of two habitats (ecotone). The increase in biodiversity of an ecotone is referred to as the edge effect. 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. especially high biological diversity over 2006).

12. Ecocline and Ecotones: Ecotone is generally confused with ecocline but there is difference in these two terms as, Ecocline is a gradation from one ecosystem to another, with no abrupt boundary between the two. Ecotone is a transitional ecosystem between two varying ecosystems, often well-defined. S uch as (wetlands are an ecotone between aquatic and terrestrial ecosystem).

13. Why are ecotones fragile? Ecotones are fragile, because they are unstable places sensitive to environmental changes as they are among the first places to show response to new environmental stresses, such as climate change, increased  grazing intensity , or pollutants.

14. Role of ecotones: Ecotone can act as a “buffer-zone” protecting the neighboring ecosystem from possible environmental damage i.e., a wetland area could absorb pollutants preventing them from seeping into a river. Ecotones provide an area for a large number of species, they often experience influx from animals looking to nest or searching for food. They may also be considered a habitat of greater  genetic diversity  and serve as   bridges of gene flow from one population to another.

15. E cotones provide a sensitive indicator of global change. Ecotones contains as many fauna and flora at the limits of their boundaries, thus any change to the local environment will be felt by these species first. Their activities therefore act as a  barometer for change.