Defining Biodiversity

The totality of genes, species and ecosystems in a given area
Different types of diversity
1. Genetic Diversity
  1. The range of genes found within a particular species. Genetic diversity often determines the degree of resistance to pests and diseases
2. Species Diversity
  1. The variety of plant and animal species present in an ecosystem.
3. Ecosystem diversity
  1. The number of different ecosystems within a given area.
Factors influencing biodiversity
1. Global and continental factors
  1. Size of area: overall biodiversity increases with area.
  2. History and age: biodiversity is greatest in the oldest and least disturbed ecosystems
  3. Isolation: geographical isolation reduces the number of species but encourages endemism. E.g. Galapagos
  4. Altitudinal range: a large altitudinal range means different climates.
2. Regional factors
  1. Productivity: high temperatures and humidity levels, rich supply of nutrients and light encourage high primary productivity
  2. Habitat architecture: High primary productivity encourages the development of a complex trophic pyramid with many ecological niches.
  3. Habitat heterogeneity: A varied physical environment will harbour greater biodiversity because it provides a wider range of habitats for a larger variety of species.
3. Local factors
  1. Succession: Biodiversity increases as species establish themselves, interact and subtly alter the environment. Well illustrated by successions that occur in sand dunes or a pond.
  2. Interaction between species: This can lead to competition which in turn may drive species to extinction
  3. Disturbance: major environmental disasters such as fires, flooding and storms can destroy biodiversity
  4. Dispersal and colonisation: Individual species' dispersal and colonisation rates have an impact on biodiversity. High rates of efficiency enhance biodiversity.
4. Human factors
  1. Undisturbed ecosystems provide a greater range of ecological niches and therefore higher levels of biodiversity. Well-managed habitats combined with effective conservation strategies can have a positive impact on biodiversity.
Areas of high biodiversity
1. Australia
2. Brazil
3. Madagascar
4. Indonesia
Biodiversity hotspot is an area containing a huge number of species, a large percentage of which are endemic
Continental hotspots are the richest in terms of biodiversity. One example is the Cape floral region in South Africa.
Ecosystem services
1. Provisioning services: products derived directly from the ecosystem, such as timber, fruits, meat and fish
2. Regulating services: those which are vital to the functioning of the Earth's systems. For example, forests as the 'green' lungs of the world and as carbon sinks.
3. Cultural services: include the aesthetic and spiritual enjoyment that people draw from them and opportunities for recreation.
4. Supporting services: processes such as nutrient cycling, soil formation and primary production that are vital to the wellbeing of the ecosystem itself.

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Defining Biodiversity

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