Ecosystem,niche and ecological succession

• Ecological Niche


  The role or job of a species in a habitat
• The word niche comes from the French word nicher, which means "to nest."
• Ecological niche


  • Describes how a species interacts with, and lives in, its habitat
  • Has specific characteristics, such as availability of nutrients, temperature, terrain, sunlight and predators, which dictate how, and how well, a species survives and reproduces
• A species carves out a niche for itself in a habitat by being able to adapt and diverge from other species
• According to the competitive exclusion principle, two species cannot occupy the same ecological niche in a habitat if they are competing for the same resources
• Aspects of an ecological niche

  • Spatial or habitat niche
  • Trophic Niche
  • Hypervolume or multidimensional niche
• Spatial or habitat niche

  Accounts for the physical space occupied by an organism
• Trophic Niche


  Tells about the functional role or trophic position occupied by a species
• Hypervolume or multidimensional niche

  Represents the position of a species in the environmental gradient. This is the fundamental niche of the species and refers to the totality of abiotic and biotic factors to which a given species is uniquely adapted
• Habitat


  A particular place where organisms live, i.e. address
• Niche


  Defines a specific role played by organisms in an ecosystem, i.e. profession
• Differences between Habitat and Niche

  • Habitat is not species-specific, and many species can occupy the same habitat
  • Niche is species-specific, and it supports only a single species
  • Habitat consists of several niches
  • Niche is specific to a particular species, which may overlap with a similar niche but must have distinct differences
  • Habitat is a superset of niche
  • Niche is a subset of habitat
• Ecological succession


  A series of changes that occur in an ecological community over time
• Ecological succession


  • Steady and gradual change in a species of a given area with respect to the changing environment
  • Predictable change and an inevitable process of nature as all the biotic components have to keep up with the changes in the environment
  • Can be related to seasonal environmental changes, which create changes in the community of plants and animals living in the ecosystem
  • May take much longer periods of time extending to several decades
• Primary succession


  Succession that starts in lifeless areas such as the regions devoid of soil or the areas where the soil is unable to sustain life
• Primary succession


  1. Rocks broken down by microorganisms and eroded to form soil

  2. Soil becomes the foundation of plant life

  3. Plants help in the survival of different animals and progress from primary succession to the climax community

  4. Organisms must start from scratch, with lichens and small plants as "pioneer species"
• Secondary succession


  Happens when a climax community or intermediate community is impacted by a disturbance, restarting the cycle of succession but not back to the beginning as soil and nutrients are still present
• Secondary succession


  1. Small plants emerge first, followed by larger plants

  2. Tall trees block the sunlight and change the structure of the organisms below the canopy

  3. Finally, the climax community arrives
• Acadia National Park (USA)


  • Suffered a huge wildfire, with small plants growing on the burnt soil initially, followed by a diversity of tree species, though the trees were mostly deciduous rather than evergreen
• Ecological Succession of Coral Reefs


  • Small coral polyps colonize the rocks, growing and dividing to form coral colonies
  • The shape of the coral reefs attracts small fish and crustaceans that are food for the larger fish, forming a fully functional coral reef