Biodiversity

mind map of the first section of the biodiversit topic in the Edexcel A2 geography text book (Dunn et al). including:

  • defining biodiversity
  • influencing factors
  • distribution and hotspots
  • the value of ecosystems
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  • Biodiversity
    • define
      • genetic
        • the range of genes found within a particular species
      • species
        • the variety of plants and animals species present in an ecosystem
      • ecosystem
        • the number of different ecosystems within a given area
    • Influencing factors
      • global and contnental
        • size of area- large biomes support a wider range of species than smaller ecosystems
        • history and age- biodiversity is greatest in the oldest and least disturbed ecosystems
        • isolation- geographical isolation (particularly on islands) reduce the number of species but encourages endemism
        • altitudinal range- a large altitudinal range means a cross-section of different climates, therefore can accommodate a wider range of species
      • regional
        • productivity- high temperatures and humidity levels, rich supplies and a lack of annual seasons increases primary productivity, therefore increasing energy
        • habitat architecture- high primary productivity encourages development of trophic levels and formation of niches
        • habitat heterogeneity- a varied physical environment means a range of habitats for an increased range of species
      • local
        • succession- biodiversity increases as species establish themselves and alter the environment
        • interaction between species- competition can cause extinction or population increase
        • disturbance- disasters such as fires, flooding and storms can destroy biodiversity
        • dispersal and colonisation- individual species' dispersal and colonisation rates impact biodiversity
      • human
        • biodiversity loss or gain
          • direct drivers of change: changes in local land use, species introduction or removal, technology adaption and use, external inputs (e.g. fertilisers), harvest and resource consumption, climate change, natural /physical  /biological drivers (e.g. evolution)
          • indirect drivers of change: demographic, economic (e.g. globalisation or trade), science and technology, cultural and religious (e.g. beliefs and consumption choices)
            • direct drivers of change: changes in local land use, species introduction or removal, technology adaption and use, external inputs (e.g. fertilisers), harvest and resource consumption, climate change, natural /physical  /biological drivers (e.g. evolution)
    • Distribution
      • biodiversity is strongly correlated with latitude, the highest levels generally occurring around in tropical countries. the highest levels of biodiversity are nearly all in developing countries.. there is a gradual decrease in biodiversity as latitude increases.
        • ranking countries according to biodiversity puts Brazil at the top. Brazil has 55000 species of flowering plant, 1635 species of bird and nearly 400 species of mammal. Brazil contains the Amazonia (largest rainforest in the world)
      • hotspots
        • define: an area containing a huge number of species, a large percentage of which are endemic. "the most remarkable places on earth, and the most threatened"
        • hotspots cover less than 2% of the earths surface and yet contain 44% of the worlds plant species and 35% of animal species.
        • continental hotspots- the richest in terms of biodiversity e.g. Fynbos
        • large island hotspots- harbour diverse and distinctive species, which can include relict fauna long extinct on the main continents
        • small island hotspots- often low in species numbers but contain a high proportion of endemics. species are often susceptible to extinction due to small populations, physical disturbances, human exploitation and vulnerability to the introduction of alien species
    • Valuing ecosystems
      • provisioning service
        • known as goods- products derived directly from the ecosystem e.g. timber
      • regulating services
        • vital to the functioning of the earths systems e.g. forests act as 'green lungs' for the world and as important carbon sinks.
      • cultural services
        • provided by ecosystems including aesthetic and spiritual enjoyment and opportunities for recreation
      • supporting services
        • processes such as nutrient cycling, soil formation and primary production that are vital to the well being of the ecosystem itself. these are not services that support people

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