Download Natural Dist-Fire

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
Forest clearcuts contribute to habitat loss
Photo by Susan Hannon
Stages of the fragmentation process
Development of
small patches within
a large area of
continuous forest
Expansion of the
developed patches
(Source: http://chesapeake.towson.edu/landscape/forestfrag/process.asp)
Ultimately to conversion
of the dominant land
cover type from forest to
human land use
Consequences of Fragmentation
(Lindenmayer and Franklin 2002)
(Meffe and Carroll 1997)
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
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.
Which features of habitat fragmentation matter?
Edge Effect

Microclimatic changes;

More light

More wind

Low humidity

Higher temperature

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.
Fragment shape
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 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.
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