Ecosystems

• An ecosystem is the living (biotic) and non-living (abiotic) components of an ecosystem
• Ecosystems


  • Vary in size and scale
  • A small ecosystem could be a garden pond
  • A large-scale ecosystem could be all tropical rainforests - this is known as a biome
• Biodiversity


  The variety of plant and animal species within an ecosystem
• Interdependence


  Within an ecosystem, the different biotic components depend on each other, and the abiotic components for survival (food, water and shelter)
• Components of a food chain/web

  • Producers
  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
  • Decomposers
• Role of decomposers


  1. Help to return energy/nutrients back to the soil

  2. Break down dead organic matter plant/animal waste

  3. Release energy from organic matter so it can be recycled
• UK Ecosystem


  • Deciduous woodland
• Producers in a deciduous woodland

  • Tree species: Elm, beech, oak and ash
  • Other plants: Holly, fern, bluebells, wild garlic
  • Lichens, mosses
• Primary consumers in a deciduous woodland

  • Insects
  • Rabbits
  • Deer
  • Squirrel (though they may eat larvae/caterpillars if conditions are harsh)
• Secondary consumers in a deciduous woodland

  • Frogs
  • Voles
  • Fox
  • Badgers
• Tertiary consumers in a deciduous woodland

  • Foxes
  • Birds of prey such as kestrels
• Animals can be in more than one trophic level

  For example, a fox will eat both primary consumers such as rabbits and secondary consumers such as voles
• There are also many decomposers (fungi) which are vital to the nutrient cycle
• Trees such as the rowan rely on birds eating the berries to disperse their seeds


  • Some berries are dropped during the flight in a new location
  • The seeds have an indigestible coating which means that seeds which are eaten are deposited in droppings
• Oak trees rely on squirrels burying the acorns to store for winter


  Acorns which are forgotten then germinate
• The trees in the woodland are mostly deciduous

  They lose their leaves covering the ground with a thick layer which then decomposes adding nutrients to the soil
• In spring before the trees come into leaf

  More light reaches the woodland floor allowing bluebells and daffodils to flower
• Deciduous woodlands in the UK have been affected by ash dieback
• Over 1000 species are dependent on ash including wood mice, wrens, bats, lichen and beetles
• The removal and death of ash trees impact all of these species which then has a knock-on effect on the species which feed on them
• Woodpeckers, other birds and small mammals which feed on the insects living on and in ash trees may experience a population decrease
• This would then impact owls and other birds of prey which feed on the smaller birds and mammals
• Ecosystem Balance


  A stable ecosystem is one where all the biotic and abiotic components are in balance so that the populations remain constant
• Natural events that can disrupt ecosystem balance

  • Wildfires caused by lightning
  • Climate change (though it can be argued this is human-induced)
  • Spread of invasive species
  • Disease
  • Extreme weather events: Flood or drought
• Human activities that can disrupt ecosystem balance

  • Deforestation
  • Hunting of animals/birds
  • Introduction of invasive species such as grey squirrels which outcompete red squirrels for food and space. They also carry a disease called squirrel pox which kills red squirrels but not grey squirrels
  • Hedgerow removal
  • Changes to water supply/drainage patterns or temperature
  • Addition of chemicals: Fertilisers/herbicides/pesticides
  • Fires used to clear land
• Factors affecting biome distribution

  • Latitude
  • Precipitation
  • Altitude
  • Continentality
  • Ocean currents
• World biomes


  • Tropical Rainforests
  • Tropical Monsoon Forest
  • Mediterranean
  • Deciduous Forest
  • Coniferous Forest
  • Savanna (tropical) Grassland
  • Temperate Grassland
  • Desert
  • Polar/tundra
• Area X receives very high rainfall which allows many plants to grow
• Area X experiences high temperatures and high rainfall which means that plants grow rapidly
• Area X receives some rain every month which means that plants grow throughout the year
• There is a hot wet climate which leads to the growth of many plants in a tropical rainforest