SCIENCE 11

• System


  Interconnected set of elements that is coherently organized to achieve a certain function or purpose
• Community


  Assemblage of populations that occupy a given area, interacting either directly or indirectly
• Ecosystem


  • Unit including all the organisms interacting with each other (biotic community) in a given area interacting with the physical environment
  • First unit in the ecological system that is complete
• Approaches to understanding ecosystems

  • Population-Community Approach
  • Process-Function Approach
• Population-Community Approach


  • Ecosystems as networks of interacting populations
  • Structure and components
  • Fails to see the bigger picture
• Process-Function Approach


  • Ecosystems as pathways of matter and energy
  • Functions and processes
  • Misses out importance of some species
• Components of a hypothetical food web

  • Basal species (producers)
  • Intermediate species (lower-level consumers)
  • Top predators (apex predators)
• Keystone species


  • Create or modify habitats and influence interaction among species
  • Impact is disproportionally large relative to its abundance
• Keystone species


  • corals
  • African elephants
  • wolves
• Ecosystem engineers


  Any organism that modifies habitat
• Types of ecosystem engineers

  • Allogenic Engineers
  • Autogenic Engineers
• Allogenic Engineers


  Modify the environment by modifying materials from one form to another
• Allogenic Engineers


  • beavers
  • earthworms
  • elephants
• Autogenic Engineers


  Modify the environment by modifying themselves
• Autogenic Engineers


  • corals
  • trees
• Landscape


  Heterogeneous area composed of several ecosystems
• Landscape ecology


  Landscape structure and processes
• Landscape matrix


  • The "primary cover type" in the landscape
  • Greater control over the flora and fauna
  • The dominant ecosystem in the landscape
• Landscape matrix


  • grassland landscape
  • forest landscape
• Landscape patch

  Homogeneous are that differs from the surrounding matrix
• Landscape corridor


  Strip of environment connecting two or more landscape patches of similar habitat
• Ecological complexity


  Differs from other analytical approaches in that it is based upon a conceptual model in which entities exist in a hierarchy of interrelated organizational levels
• Parameters of a complex system

  • Numerosity
  • Non-linearity
  • Connectivity
  • Autonomy and Adaptation
• Numerosity


  Number of elements in different levels to the hierarchy within our system
• Non-linearity


  Interactions and feedback loops over time
• Connectivity


  Indicates the degree of how things flow in the networks
• Autonomy and Adaptation


  Enables self-organization and the process of evolution that shapes complex systems on macro scale (ecological memory)
• Dimensions of ecological complexity

  • Spatial
  • Temporal
  • Structural
• Spatial complexity


  Distribution defines the spatial extent of a population ecosystem (e.g. vegetation patterns, species distribution)
• Natural boundaries


  • Edge: marks the perimeters of each patch
  • Border: place where the edge of one patch meets the edge of another
  • Ecotone: wider border
• Edge effect


  More diversity at the borders or boundary of two or more habitats
• Temporal complexity


  The time series of different variable describing the dynamics of a system
• Examples of temporal complexity

  • Changes in the Population
  • Effects of Change in Climate and Weather
  • Extinction Rate
  • Invasion Rate
  • Succession
• Primary succession


  Takes a long time to reach the climax community
• Secondary succession


  Faster than the primary succession
• Predator-prey cycles


  As predators decrease the number of the prey eventually lacks food resources, which in turn, decreases the predators' abundance. The decrease in the prey population eventually leads to a decrease in predator abundance. Due to the lack of predation pressure or low numbers of predators, would now let the prey population rebound or increases in number. Also, as the prey's population increases in size, more food hence increasing the population size of the predator.
• Structural complexity


  Relationships within the ecosystem (food web)
• Hubs


  Most number of interactions
• From a conservation standpoint, among the four kinds of networks, the more complex and ideal habitat may resemble a scale-free network with several large hubs connected to multiple nodes
• Node 12


  Designated hub, regarded as a high-degree node or high-quality patch warranting conservation and monitoring efforts