Ecosystems

Population: all the organisms of one species that live in the same place and the same time and that can breed together

Habitat: the place where an organism lives (e.g. pond, field, wood)

Community: all the populations of different species who live in the same place at the same time and can interact with each other

Ecosystem: any group of living organisms and non living things occurring together and their interrelationships. (i.e. the interactions between the community and habitat)

Niche: the role that each species plays in an ecosystem

Factors that affect ecosystems

  • Abiotic (non-living things)

    • Sunlight

    • Temperature

    • Soil

      • pH

      • Moisture

      • Type

    • Water

      • Humidity

    • Oxygen/carbon dioxide levels (mainly for aquatic life)

    • Wind

    • Aspect, orientation

  • Biotic (living things)

    • Disease

    • Predators

    • Food

    • Competition

      • Interspecific - different species

      • Intraspecific - same species

    • Territory/space

    • [Human activity]

    • Breeding partners

Ecosystem: Made up of all the living organisms that interact with one another in a defined area, and also the physical factors present in that region

E.g.

  • Rock pool

  • Playing field

  • Tree

  • Entire biosphere of Earth

  • Tiny colony of bacteria

Dynamic ecosystems

  • Ecosystems are dynamic (i.e. constantly changing). Populations in the community fluctuate depending on many factors, e.g. predation, seasonal changes etc.

  • All populations are linked to all other populations

Energy and matter in ecosystems

  • Energy flows through an ecosystem and will eventually be lost as heat energy

  • All matter is cycled (e.g. carbon and nitrogen cycle)

efficiency = total energy converted to biomass/total energy in x 100

Measuring biomass

  • Mass of fresh material present

    • Easiest method but unreliable as mass of water varies greatly

  • Dry mass

    • Most accurate but organisms have to be killed and put into an oven at 80oC to evaporate all the water

Net production / kJm-2year-1 = gross production - respiratory losses

  • Net production: energy available to pass on to next trophic level

  • Gross production: total solar energy that plants convert to organic matter

  • Respiratory losses: plants use 20-50% of their energy for respiration