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Planet Earth. Ecosystems of the world (Biomes)

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Presentation on theme: "Planet Earth. Ecosystems of the world (Biomes)"— Presentation transcript:

1 Planet Earth

2 Ecosystems of the world (Biomes)

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9 Energy in EcosystemsProductivity Energy available to next level in food chain is: GPP - R = NPP (Net primary productivity) Plants also use energy in respiration (R) Total primary productivity is known as Gross Primary Productivity (GPP) Primary productivity is the amount of light energy fixed into chemical energy in a certain length of time. Energy is fixed primarily by auto-trophs during photosynthesis.

10 Measuring productivity Net primary productivity is the biomass after respiration energy is taken into account. Gross primary productivity is the total yield of organic matter from photosynthesis. Primary productivity = the biomass of vegetation added to an ecosystem per unit area in a certain time (e.g. g/m 2 /year)

11 Factors affecting primary productivity Aquatic ecosystems light, inorganic nutrients Terrestrial ecosystems precipitation, temperature, light, inorganic nutrients Examples: Seasonal changes Type of ecosystem Soil nutrients/water Temperature, light intensity, supply of CO 2

12 Energy Flow primary, secondary and tertiary consumers Herbivores, carnivores, omnivores, decomposers Niche is an organisms role in an ecosystem. Ecological niches Food chains and food webs.

13 Feeding relationships Range of efficiencies 5 - 20% depends on ecosystem 90% used by previous organism (heat energy, respiration, undigested waste, movement each link in chain 10% energy available for next level plants use 1% of light energy Energy transfer - not efficient Trophic levels - represent feeding levels in a food chain

14 Representations of productivity Pyramids of  productivity  biomass  numbers

15 Pyramid of numbers numbers of organisms counted and grouped into trophic levels exceptions include when a tree is supporting many insects and birds

16 Pyramid of Biomass total mass of organisms at each trophic level exceptions occur when primary consumers outweigh primary producers e.g. aquatic ecosystems Wet mass v dry mass

17 Pyramid of Productivity Energy available at each level to be passed on to next level. Energy is always less at each trophic level.

18 Measuring productivity Net primary productivity is the biomass after respiration energy is taken into account. Gross primary productivity is the total yield of organic matter from photosynthesis. Primary productivity = the biomass of vegetation added to an ecosystem per unit area in a certain time (e.g. g/m 2 /year)

19 Ultimate loss of energy is as heat from respiration, as organic materials are broken down by decomposers into inorganic materials to be reused Decomposers


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