Defining Biodiversity

Defining Biodiversity

1. The totality of genes, species and ecosystems in a given area

2. Different types of diversity

   • Genetic Diversity
     • The range of genes found within a particular species. Genetic diversity often determines the degree of resistance to pests and diseases
   • Species Diversity
     • The variety of plant and animal species present in an ecosystem.
   • Ecosystem diversity
     • The number of different ecosystems within a given area.

3. Factors influencing biodiversity

   • Global and continental factors
     • Size of area: overall biodiversity increases with area.
     • History and age: biodiversity is greatest in the oldest and least disturbed ecosystems
     • Isolation: geographical isolation reduces the number of species but encourages endemism. E.g. Galapagos
     • Altitudinal range: a large altitudinal range means different climates.
   • Regional factors
     • Productivity: high temperatures and humidity levels, rich supply of nutrients and light encourage high primary productivity
     • Habitat architecture: High primary productivity encourages the development of a complex trophic pyramid with many ecological niches.
     • Habitat heterogeneity: A varied physical environment will harbour greater biodiversity because it provides a wider range of habitats for a larger variety of species.
   • Local factors
     • 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.
     • Interaction between species: This can lead to competition which in turn may drive species to extinction
     • Disturbance: major environmental disasters such as fires, flooding and storms can destroy biodiversity
     • Dispersal and colonisation: Individual species' dispersal and colonisation rates have an impact on biodiversity. High rates of efficiency enhance biodiversity.
   • Human factors
     • 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.

4. Areas of high biodiversity

   • Australia
   • Brazil
   • Madagascar
   • Indonesia

5. Biodiversity hotspot is an area containing a huge number of species, a large percentage of which are endemic

6. Continental hotspots are the richest in terms of biodiversity. One example is the Cape floral region in South Africa.

7. Ecosystem services

   • Provisioning services: products derived directly from the ecosystem, such as timber, fruits, meat and fish
   • 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.
   • Cultural services: include the aesthetic and spiritual enjoyment that people draw from them and opportunities for recreation.
   • Supporting services: processes such as nutrient cycling, soil formation and primary production that are vital to the wellbeing of the ecosystem itself.