Biodiversity within a community

• BIODIVERSITY (the complexity of a biological community, can be measured using species richness):

  • HABITATS: (habitat= an area which an organism lives in) Biodiversity exists in habitats at a range of sizes. Biodiversity can be considered in a small local habitat (eg a lake) and biodiversity varies between habitats (eg coral reefs are typically more diverse than meadows)
• BIODIVERSITY (the complexity of a biological community, can be measured using species richness):

  • GLOBAL BIODIVERSITY: Biodiversity can be considered on the global scale & varies around the world (eg the equator is usually more biodiverse than the poles)
  • ECOSYSTEM DIVERSITY: the range of different habitats (from a small local habitat to the whole of Earth)
  • GENETIC DIVERSITY; the variety of genes of individuals in a species
  • SPECIES DIVERSITY: the number of different species & the number of individuals of each species in a community
• BIODIVERSITY (the complexity of a biological community, can be measured using species richness):

  • SPECIES RICHNESS: the number of species in a habitat/ community
  • SPECIES ABUNDANCE: The number of individuals in each species
• INDEX OF DIVERSITY (uses species richness and species abundance):

  • THE EQUATION: N= total number of organisms of all species present, n= total number of organisms of one given species present
  • BENEFITS OF THE INDEX: Instead of only species richness it takes into account the population sizes of different species in one community (the greater value for the index of diversity, the more diverse the community)
• INDEX OF DIVERSITY (uses species richness and species abundance):

  • ECOSYSTEM STABILITY: Higher index of diversity, the more stable an ecosystem is (less affected by change eg more likely to have at least 1 species able to tolerate a drought). Extreme environments= low index of diversity= unstable ecosystem, dominated by climatic factors rather than the organisms in the community
• INDEX OF DIVERSITY:

  
• IMPACT OF AGRICULTURE (main impact= diminish the variety of habitats & reduce species diversity):

  • MONOCULTURE: When crops are grown over a large scale for agriculture, one type of crop (a monoculture) species covers many fields -> decreases biodiversity. Few species can survive monoculture environments (as if most area is taken up by one species, then the other species will have to compete for little space left & the little resources available-many wont survive this competition -> many species’ populations would be reduced). The index of biodiversity is low in agricultural ecosystems
• IMPACT OF AGRICULTURE (main impact= diminish the variety of habitats & reduce species diversity):

  • HERBICIDES: Are sprayed onto crops to prevent growth of unwanted plants/ weeds. Herbicides reduce biodiversity as: They direct removal of plants. Species that feed on the unwanted plants cannot survive.
• IMPACT OF AGRICULTURE (main impact= diminish the variety of habitats & reduce species diversity):

  • DEFORESTATION:  Large regions of forests are cleared to provide space for crop or livestock farms. Forests are biodiverse environments as there are many different habitats of different species. Removal of forests reduces biodiversity as: The direct removal of species (e.g. trees). The removal of habitats -> causing species to die. There has also been the removal of hedgerows & grubbing out woodland
  • PONDS: Filling in ponds, draining marsh/ other wetland
• CONSERVATION VS FARMING:

  • PROTECTING ENDANGERED SPECIES: Endangered species can be protected to avoid extinction eg tigers have lost significant parts of their habitat due to agriculture. Protection of tigers have helped increase their population sizes
• CONSERVATION VS FARMING:

  • PROTECTING AREAS: Specific areas with high biodiversity can be protected, and therefore cannot be developed into farmland (eg sites of special scientific interest)
• CONSERVATION VS FARMING:

  • ENVIRONMENTAL STEWARDSHIP SCHEME; Farmers are encouraged to balance agriculture with conserving biodiversity (eg allowing plants to grow around fields)
• CONSERVATION VS FARMING:

  • OTHER METHODS OF CONSERVATION; Maintaining hedgerows (as an A shape rather than rectangular as its more effective), plant hedges rather tan fences as field boundaries, maining & create ponds, leave wet corners on fields rather than draining them, plant native trees in low diversity areas, reduce use of pesticides & herbicides & use organic fertilisers, use crop rotation to improve soil fertility, use intercropping rather than herbicides
• CONSERVATION VS FARMING:

  • CONSERVATION VS FARMING: Despite its negative environmental impacts, agriculture is necessary to support the growing human population. Problem with conservation= more expensive to implement