4.6- HABITAT LOSS or FRAGMENTATION

What is Habitat Fragmentation? Why is it happening? What are its consequences?

Habitat fragmentation involves alteration of habitat resulting in spatial separation of habitat units from a previous state of greater continuity. It is the process by which habitat loss results in the division of large, continuous habitats into smaller, more isolated remnants.

The major reasons for habitat fragmentation are:

Natural/Geological Factors:

1.  Glacial advances

2.  Volcanic activities

3.  Geologic faulting, tectonic movements

4.  Mass land slumping

5.  Major sea level rise and climate oscillation

Anthropogenic factors:

1.  Agricultural land conversion

2.  Urbanization

3.  Pollution, deforestation and introduction of exotic species

4.  Human caused wildfires as well as the systematic practice of fire suppression

Consequences of habitat fragmentation are:

1.  It characteristically reduces species richness and taxon diversity, and may reduce the efficacy of ecosystem functioning.

2.  Small fragments of habitat can only support small populations of plants and animals and small populations are more vulnerable to extinction.

3.  Mobile animals (especially birds and mammals) retreat into remnant patches of habitat. This can lead to crowding effects and increased competition.

4.  It leads to edge effects (i.e. the changes in population or community structures that occur at the boundary of two habitat)

5.  In some cases already dominant or keystone species grows rapidly usually at the expense of reducing populations of (if not elimination of) other species.

6.  Due to restricted gene flow species may suffer from genetic drift or inbreeding and have difficulty in re-colonizing.

Habitat fragmentation on large scale to due human activities has induced worldwide reduction in biodiversity and interruption of sustainable yields of natural resources. This issue needs to be actively resolved by taking steps like preserving or planting corridors of native vegetation and enlargement of small remnants.