- Fragmentation breaks up contiguous tracts of natural habitats into smaller patches. In a fragmented landscape where a previously large forest has become a mosaic of patches of different sizes, the following statements can be made about the fragment size and its species diversity.
A. Smaller fragments will always have lower species richness than larger fragments
B. Species richness will depend on fragment size.
C. Species richness will depend on physical connectivity between fragments
D. Species richness cannot be compared between large and small fragments
Select the option where both the statements are correct
(1) A and B (2) B and C
(3) A and C (4) B and DUnderstanding the Effects of Fragmentation
When a large habitat is fragmented, the resulting patches differ in size, isolation, and edge effects. These factors interact to shape the number and types of species that can persist in each fragment.
Fragment Size and Species Richness
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Species-Area Relationship: Larger fragments generally support more species than smaller ones. This is a well-established principle in ecology, known as the species-area relationship. Larger patches offer more resources, diverse microhabitats, and can sustain larger populations, reducing the risk of local extinction.
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Not Always Absolute: However, the relationship is not absolute. While smaller fragments tend to have lower species richness, exceptions exist, and the effect can be influenced by the total amount of habitat and the specific ecology of the species involved35.
Connectivity Between Fragments
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Physical Connectivity: The degree of connectivity between habitat patches—such as through wildlife corridors or proximity—plays a crucial role in maintaining species richness. Well-connected fragments allow for movement of individuals, gene flow, and recolonization, which can counteract the negative effects of isolation37.
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Isolation Increases Extinction: Isolated fragments are more prone to species loss, as recolonization after local extinctions becomes less likely.
Evaluating the Statements
Let’s analyze the provided statements:
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A. Smaller fragments will always have lower species richness than larger fragments
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B. Species richness will depend on fragment size
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C. Species richness will depend on physical connectivity between fragments
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D. Species richness cannot be compared between large and small fragments
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This is incorrect. Species richness is routinely compared across fragments of different sizes in ecological research.
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The Correct Option
Option (2) B and C is correct.
Species richness in fragmented landscapes depends both on the size of the fragment and on the physical connectivity between fragments.Why This Matters for Conservation
Understanding these dynamics is critical for effective conservation planning:
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Prioritize Large and Connected Patches: Conservation efforts should focus on preserving large habitat patches and enhancing connectivity between fragments.
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Design Wildlife Corridors: Creating corridors or stepping stones can help maintain or restore biodiversity in fragmented landscapes.
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Monitor Both Size and Connectivity: Both factors must be considered to predict and manage species richness after fragmentation.
Conclusion
In fragmented landscapes, species richness is influenced by both fragment size and the physical connectivity between fragments. While larger patches generally support more species, connectivity enables movement and recolonization, helping maintain biodiversity across the landscape. Conservation strategies that address both factors are essential for sustaining species diversity in an increasingly fragmented world.
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