key definitions

• ecosystem 


  a natural system made up of plants, animals and the environment
• local ecosystem


  an ecosystem on a small scale, known as 'habitat', such as a pond or woodland
• regional ecosystem

  an ecosystem on a medium scale such as a moorland area
• global ecosystem


  an ecosystem on a large scale such as a tropical rainforest. also known as biomes
• biotic


  living parts of an ecosystem
• abiotic 


  non-living parts of an ecosystem
• biome


  a large scale ecosystem, covering a large area of the earths surface
• producer 


  an organism or plants able to convert energy from the sun by photosynthesis
• consumer


  an organism that east herbivores and/or plant matter
• herbivore


  plant eating insects or animals such as cows
• carnivore 


  animals which feed on herbivores such as foxes or cats
• top carnivore


  animals which hunt and will eat other carnivores in the ecosystem as well as herbivores. these include lions and wolves
• decomposer


  an organism such as bacteria or fungus that breaks down dead tissue, which is then recycled back into the environment
• food chain


  the direct links between producers and consumers in the form of a line
• food web


  the connections between producers and consumers in a complex way with several 'branches'
• biomass


  the total quantity or weight of organisms in a given area, or volume
• biodiversity


  the variety of life in the world, or particular habitat or ecosystem
• nutrient cycling


  a set of processes whereby organisms extract minerals necessary for growth from soil or water, before passing them on through the food chain and ultimately, after death, back into the soil and water
• trophic levels 


  any of the sequential changes in a food chain, occupied by producers at the bottom and in turn by primary, secondary and tertiary consumers. decomposers are sometimes considered to occupy their own level. the rate at which energy is transferred from one level to the next is called the ecological efficiency
• physical linkage 


  a link between different parts of the ecosystem that are physical e.g animals eating plants
• chemical linkage


  a link between different parts of the ecosystem that are chemical e.g. mild acids in rainwater speed up the decay of dead leaves