both

• Ecosystem

  Comprises of two factors: abiotic and biotic
• Biotic


  The living components of an environment
• Abiotic


  The non-living components of an environment, e.g. temperature, water availability and light
• Habitat


  The place where an organism normally lives. In one ecosystem there might be many habitats
• Population


  All of the organisms of one species in a particular habitat/A group of interbreeding organisms living in the same place
• Community


  All of the populations of different species living in the same place at the same time
• When referring to communities in an ecosystem the place in which the community lies must be specified as to which habitat
• Communities can be all different sizes
• Ecosystem


  A combination of all of the biotic and abiotic factors in a particular area
• Abiotic factors


  • Temperature
  • Light intensity
  • pH
  • Water availability + Humidity
  • Size of an area
• Temperature


  • Each species has a specific optimum temperature at which it survives best
  • The further away a habitat is from this temperature, the lower the carrying capacity
  • Depends on whether the species can regulate its temperature internally
• Ectotherms


  Organisms that cannot control their internal temperature
• Endotherms


  Organisms that can control their internal temperature
• Light intensity


  • All energy from an ecosystem comes from a light source - the sun
  • Photosynthesis is the process in which plants convert light energy to chemical energy
  • As light intensity increases, rate of photosynthesis increases → growth and maturity rate increases → carrying capacity of plants increased
  • Too much light may also be damaging
• pH


  • A measure of how acidic the environment is
  • The closer the environment is to the optimum pH, the faster the catalysis of metabolic reactions and the greater the carrying capacity
• Water availability + Humidity


  • The carrying capacity of a species is affected by water availability and humidity
  • Humid conditions → Less evaporation → Less transpiration
  • Plants are adapted to live and transpire in a particular humidity
• Size of an area

  • The amount of biomass a population has to feed on affects its population size
  • Different populations require differently sized habitats
  • Different organisms are adapted to survive in different depths (marine ecosystems)
• Carrying capacity


  The maximum number, density, or biomass of a population that a specific area can support sustainably
• Conditions in the ecosystem make it easier or harder for a particular organism to survive and reproduce
• The harder it is to survive and reproduce the smaller the carrying capacity → the species average population size in a particular area
• Biotic factors


  The living components of an ecosystem, including actions and interactions of animals, plants, fungi and bacteria
• A combination of biotic and abiotic factors will influence the survival of a particular species
• Biotic and abiotic factors interact with each other to determine the characteristics of an ecosystem
• Food availability


  • Most organisms need to eat other organisms to survive
  • The only organisms that don't depend on other organisms to survive are producers which generate their own chemical energy via photosynthesis
  • If there is high food availability for a consumer, its population size will be large
• Predation


  • Predation helps to maintain the population sizes of species in lower trophic levels
  • The arrival of a new predator in an ecosystem can dramatically reduce the population of a species it preys upon
  • Lots of predators → less population size of a species
• Disease


  • Disease reduces the population size of affected species
• Competition


  • Organisms compete with each other for resources e.g. food, habitat
• Food chains


  A system that shows one form of energy transfer between a set of species
• Photosynthesis


  The process in which plants convert light energy to chemical energy
• Photosynthesis is the only process that produces biomass
• Plants and algae are the only organisms that can photosynthesize
• Trophic levels


  • 1st - Producer (responsible for providing accessible energy for the whole ecosystem)
  • 2nd - Consumer (can't produce food on its own)
  • Consumer that feeds on producer - primary consumer
  • Consumer that feeds on primary consumers - secondary consumers
  • Consumer that feeds on secondary consumer - tertiary consumers/apex predator
• Food webs


  A network of interconnected food chains
• All the energy ends up at the apex predator
• A complex food web = healthy food web</b>
• Sampling


  Measuring a proportion of a population in an ecosystem, where the samples are representative of the rest of the population
• Species abundance


  The number of individuals of a species in a particular area
• Species distribution


  How the number of individuals in a species changes over a specific area
• Quadrats


  Grids used for sampling non-moving organisms e.g. plants and fungi
• Using quadrats to measure abundance

  1. Create a coordinate axis encompassing the area

  2. Generate random numbers to act as coordinates for quadrat placement

  3. Count the number of individuals or percentage cover

  4. Repeat to obtain a large sample size

  5. Calculate the mean and scale up to estimate for the whole area