Ecology

• Ecology


  The study of how organisms interact with each other
• Factors that influence species interactions in an ecosystem

  • Abiotic
  • Biotic
• Individual species


  A single organism of a particular species
• Population


  A group of the same species living in the same area
• Community


  All the populations of different species living in the same area and interacting with each other
• Ecosystem


  A community of living organisms (biotic) interacting with each other and their physical environment (abiotic)
• Ecotones


  • Transition zones between ecosystems
  • Have greater biodiversity
  • Tend to be less fragile
• Ecological niche


  The organism's place in the food web, its habitat, breeding area, and the time of day that it is most active
• The difference between a habitat and niche is that a habitat is the physical environment where an organism lives, while a niche is the organism's role and position in that environment
• When a new species enters an ecosystem

  It causes a disturbance because there is competition between one or more species already in the ecosystem
• Invasive species


  • Often there are no predators so the introduced species population can increase rapidly
  • Native species might not be able to compete successfully for space, food, reproductive sites
  • Prey species might not have defences against the new species
• Abiotic limiting factors for plants

  • Soil type
  • Moisture and humidity levels
  • Temperature range
  • Fertilizer use
• Biotic limiting factors


  • Competition for resources
  • Predators
  • Parasites
• Intraspecific competition


  Members of the same type of population compete with each other for a limited resource
• Interspecific competition


  Members of different species populations compete with each other for a limited resource
• Interspecific competition may result in


  One species outcompeting the other and not being able to survive in that habitat, or them being able to coexist in the habitat but the population being lowered due to the presence of the other species
• Predation


  A biotic interaction that involves the consumption of one organism by another
• Parasitism


  An interaction in which one organism (the parasite) derives its nourishment from another organism (the host) which is harmed in some way
• Increase in the density of the host population


  Makes it possible for the parasite to increase in number
• Factors that limit populations


  • Factors that cause a population to increase
  • Factors that cause a population to decrease
• Abiotic factors that limit populations

  • Favorable light
  • Favorable temperature
  • Favorable chemical environment
  • Too much or too little light
  • Too cold or too warm
  • Unfavorable chemical environment
• Biotic factors that limit populations


  • Sufficient food
  • Low number or low effectiveness of predators
  • Few or weak diseases or parasites
  • Ability to compete for resources
  • Insufficient food
  • High number or high effectiveness of predators
  • Many or strong diseases or parasites
  • Inability to compete successfully for resources
• Biome


  A specific area with a distinct environmental conditions, climate, vegetation and species that live there
• Taiga biome


  • Coniferous forests
  • Warm moist summers/dry cold winters
  • Weather changes quickly
  • Soil contains some water and is acidic
  • Precipitation is 50-250cm/year
• Muskeg biome


  • Cold
  • Permafrost
  • Forms muskeg (water soaks decomposing plants and peat moss)
  • Short growing season
  • Low precipitation (50-150 cm/a)
• Grassland biome


  • Increased temperature and sunlight than taiga and muskeg
  • Rich soil
  • Precipitation 25-100 cm/a
• Deciduous forest biome


  • Mostly trees
  • Increased sunlight and temperature than taiga and muskeg
  • Rich soil
  • Precipitation 75-250 cm/a
• Abiotic factors


  Non-living components of an ecosystem that affect living organisms
• Terrestrial ecosystems


  • Affected by soil conditions (pH, soil type)
  • Available water
  • Temperature
  • Sunlight
• Soil


  1. Upper layer (litter) - partially decomposed leaves/grasses, acts as a blanket limiting temperature variations

  2. Topsoil - small rock particles mixed with decaying matter (humus), often dark, rich in nutrients, air and water spaces

  3. Subsoil - more rock particles, small amounts of organic matter, lighter in colour, contains minerals

  4. Bedrock - layer of rock marking end of soil

  5. Groundwater - water found within the soil
• Aquatic ecosystems


  • Affected by chemical environment (fresh/saltwater, dissolved oxygen, other dissolved substances)
  • Temperature
  • Sunlight
  • Water pressure (increases with depth)
• As temperature increases


  Dissolved oxygen decreases
• As dissolved oxygen begins to drop


  Fewer organisms can be supported
• Biological Oxygen Demand (BOD)


  • Measure of dissolved oxygen needed by decomposers to break down organic matter in water over 5 days at 20°C
  • Indicates amount of available organic matter in water sample
• As number of organisms increases

  Biological oxygen demand increases
• As biological oxygen demand increases


  Dissolved oxygen levels decrease
• Lake ecosystems


  • Abiotic factors influence biotic factors
  • Sunlight varies at different lake zones, impacting plant growth
  • Water density and temperature vary seasonally
• Seasonal variation in Canadian lakes

  1. Winter - lake covered in ice/snow, water density layers, low sunlight, low dissolved oxygen

  2. Spring - ice melts, oxygen enters, water mixes, temperature increases

  3. Summer - upper layer warms, lower layer stays cold, layers don't mix, oxygen issues

  4. Fall - temperature drops, water mixes, oxygen levels renewed
• Changes In Terrestrial Ecosystems

  • Forestry Practices
• Forestry Method


  • Slash and burn
  • Clear - cutting
  • Selective cutting