Ecosystem Ecology

• Ecosystem


  Populations interacting with each other and their abiotic environment
• Abiotic Factors


  • Chemical factors
  • Physical factors
• Biotic Factors


  • Producers
  • Consumers
  • Decomposers
• Abiotic Factors


  • Chemical/physical environmental factors which influence distribution of organisms
• Abiotic Factors


  • Climatic factors (e.g. temperature, rainfall)
  • Edaphic factors (e.g. soil pH, soil type)
  • Other factors (e.g. oxygen concentration in water, water currents, light intensity)
• Photoautotrophs


  Organisms that require light for photosynthesis
• Light intensity


  Directly affects plants, algae, cyanobacteria
• Daylight hours


  Influence development of flowers (photoperiod)
• Light


  Can make plants adapt to maximise absorption (e.g. larger leaves, more sensitive pigments)
• Light


  Influences bird behaviour and migration
• Water availability


  Issue for all terrestrial species
• Water


  Medium for transport and metabolic reactions
• Organisms adapted to water

  • Cacti, camels
• Precipitation/rainfall


  Affects water availability
• Soil erosion


  Increases turbidity, reduces light penetration
• Temperature


  Influences enzymes and metabolic reactions
• Temperature


  Affects rate of growth and development
• Temperature


  Induces migration and hibernation
• Adaptations to temperature


  • Anti-freezing compounds in fish blood, endotherms regulating internal temperature
• Oxygen availability


  Limiting factor in soil and water
• Waterlogged soils


  Lack oxygen, affecting plant growth
• Slow, hot water


  Leads to anoxic conditions
• pH


  Optimum for enzymes, some organisms tolerate wider ranges than others
• Edaphic factors


  Abiotic factors due to physical, chemical and biological features of soil
• Soil types


  • Clay soil
  • Loam soil
  • Sandy soil
• Soil texture


  Proportions of sand, silt and clay
• Soil permeability


  Ease with which water, air and roots move through soil
• Soil air


  Air spaces between soil particles, determines firmness and provides oxygen for aerobic respiration
• Soil temperature


  Varies in upper layers, more steady in deeper parts, affects rate of decomposition by decomposers
• Soil water


  Soil particles retain a film of water which is taken up by plants
• Soil pH


  Affects biological activity in soil and availability of mineral ions
• Mineral ion content


  Needed and taken up by plant roots by active transport (e.g. nitrogen for amino acids, magnesium for chlorophyll)
• Plants in nitrogen-deficient soils


  Either become insectivores or have a mutualistic relationship with nitrogen-fixing bacteria
• Biotic Components


  • Producers
  • Consumers
  • Detrivores
  • Decomposers
• Producers


  Autotrophs that fix inorganic carbon into biomolecules and biomass, occupy the first trophic level
• Producers


  • Photoautotrophs (e.g. plants, algae, cyanobacteria)
  • Chemoautotrophs (e.g. bacteria in hydrothermal vents)
• Consumers


  Heterotrophs that obtain energy by feeding on living/organic matter, include herbivores, insectivores, omnivores, carnivores, filter feeders
• Detrivores


  Consumers that feed on fragments of dead plants/animals or animal waste, shred and process organic matter for eventual bacterial decomposition
• Decomposers


  Break down organic matter into inorganic chemicals, CO2 and H2O, involved in nutrient cycling
• Decomposers


  • Saprophytes (e.g. ammonifying bacteria Pseudomonas)