Habitat Fragmentation

By

Kaushik Mysorekar

Objective

To enlighten the causes and consequences of habitat fragmentation followed by few recommendations to restore biodiversity and natural environment/habitat and prevent of fragmentation.

What is habitat fragmentation?

Breaking up of large continuous habitat into smaller and isolated parcels.

Or transformation of original continuous forest landscape into smaller and isolated remnant patches of plantation or non-forest habitat.

Or simply disruption of continuity.

Natural Disturbance -Fire

         Photo by Susan Hannon

Forest clearcuts contribute to habitat loss

 (Source: http://chesapeake.towson.edu/landscape/forestfrag/process.asp)

Stages of the fragmentation process

Development of small patches within a large area of continuous forest

Expansion of the developed patches

Ultimately to conversion of the dominant land cover type from forest to human land use

Consequences of Fragmentation

Major ecological consequences of habitat fragmentation are

Habitat loss

Subdivision of habitat

Patch isolation

Edge effects

Others o• Loss of native plants and animal species

• Invasion of exotic species

• Increased soil erosion

• Decreased water quality

(Lindenmayer and Franklin 2002)

(Meffe and Carroll 1997)

Species vulnerable to habitat fragmentation

(Meffe and Carroll 1997)

Rare species

Species with large home ranges

Species with limited power of dispersal

Species with low reproductive potential

Species with short life cycle

Species of habitat interior

Species dependent on resources that are unpredictable in time or space

Ground nesting birds

Species exploited or persecuted by people.

Edge Effect

Microclimatic changes; More light

More wind

Low humidity

Higher temperature

Which features of habitat fragmentation matter?

Alters native plants and animals;

Reduce the survival of the species of the original habitat;

Advantageous for invasive species;

Consequentially excluding the native species.

Fragment size/area

Influences the ecological processes occurring therein

Large fragments have

variety of soil types

greater topographic

microclimatic variation

greater number of habitat types

Smaller fragments - larger edge habitat and less interior;

larger fragments- less edge habitat and larger interior;

Species richness decreases with decrease in fragment area.

Shape can be calculated by perimeter/area ratio

Square - low P/A ratio- greater interior

than rectangle of the same area;

Surprisingly US have high P/A ratio

for the reserves for nature protection;

Fragments with a highly irregular ,convoluted boundary will have greater exchange of nutrients,materials and organisms.

Fragment shape

Fragment Connectivity

Fragments are connected by corridors (fencerows, streams, roads), which does ecological functions such as

Connectivity with riparian corridors is important to prevent soil erosion and to maintain high water quality;

Wide corridors reduce the edge effects & human disturbances;

Vegetative corridors facilitate the movement the of animals and plants and prevents species extinction.

Fragment heterogeneity

Heterogeneous fragments support greater number and variety of species;

Heterogeneous fragments show greater variation of microclimate;

Plants and animals are less susceptible to local extinction.

Recommendations

(Meffe and Carroll

1997) (Collinge 1996)

(Lindenmayer and Franklin 2002)

Conduct a landscape analysis, determine the pattern of habitats and connections;

Avoid any further fragmentation or isolation of natural areas and;

Edge effects can be minimized by establishing buffer zones;

Recommendations cont.

Maintain native vegetation along streams, fencerows, roadsides, to minimize edge effects and human disturbances;

Protect traditional wildlife migration route and human activities should be steered away;

Minimize the area dominated by weedy or exotic species (roadsides);

Activities against natural disturbances such as fire, windthrows are important for native flora and fauna.

THANK YOU