BIOSPHERE NASA © 2016 Paul Billiet ODWS

Biosphere Atmosphere © 2016 Paul Billiet ODWS

Biosphere The part of the Earth where life is found The parts where there is interaction between the living organisms and their non-living environment. © 2016 Paul Billiet ODWS

Solar radiation © 2016 Paul Billiet ODWS

Energy enters and leaves an ecosystem It is NOT recycled ENERGY FLOW Energy enters and leaves an ecosystem It is NOT recycled © 2016 Paul Billiet ODWS

Organisms and energy Autotrophs Heterotrophs © 2016 Paul Billiet ODWS

Autotrophs Photoautotrophs Chemoautotrophs © 2016 Paul Billiet ODWS

Heterotrophs Predators – carnivores Grazers – herbivores Decomposers – saprotrophs, detritivores © 2016 Paul Billiet ODWS

Trophic levels Producers = autotrophs 1er consumers = herbivores (or decomposers) 2nd consumers = carnivores 3rt consumers = carnivores 4ry consumers = (top carnivores) © 2016 Paul Billiet ODWS

Trophic levels 1st level = producers = autotrophs 2nd level = 1er consumers = herbivores 3rd level = 2nd consumers = 1st carnivores 4th level = 3rt consumers = 2nd carnivores 5th level = 4ry consumers = top carnivores © 2016 Paul Billiet ODWS

Food chains Heron Small fish Mayfly larvae Algae © 2016 Paul Billiet ODWS

SUN LIGHT ENERGY 50% 5% 15% 21% Dust 3% Clouds 6% GROUND © 2016 Paul Billiet ODWS

Energy loss © 2016 Paul Billiet ODWS

In the leaf GP = Gross production NP = Net production NP = GP - R © 2016 Paul Billiet ODWS

Productivity © 2016 Paul Billiet ODWS

Energy loss in a food chain users.rcn.com/.../BiologyPages/F/FoodChains.html. © 2016 Paul Billiet ODWS

Energy limits food chains Food chains are finite Rarely more than 5 organisms long Energy only enters via the producers For terrestrial ecosystems, energy enters as sunlight Chemical energy flows up the food chain At each link in the chain energy is lost through respiration… as heat Or it is not consumed  decomposers. © 2016 Paul Billiet ODWS

Energy and consumers The loss at each trophic level of consumers is about 90% Only 10% passes to the next level This limits the length of the food chain. © 2016 Paul Billiet ODWS

Limitation of food chains Simplified diagrams of energy flow Do not show the whole community So do not show interactions Many organisms feed at different trophic levels E.g. Omnivores Most have a varied diet at the same level. © 2016 Paul Billiet ODWS

Food webs © 2016 Paul Billiet ODWS

© 2016 Paul Billiet ODWS

Humans are part of a food web © 2016 Paul Billiet ODWS

© 2016 Paul Billiet ODWS

© 2016 Paul Billiet ODWS

Pyramids A quantitative approach to energy flow Pyramids of numbers Pyramids of biomass Pyramids of energy © 2016 Paul Billiet ODWS

Pyramid of numbers At higher trophic levels the numbers of consumers gets smaller Less energy to support another level So there are a lot of producers and progressively less and less at higher trophic levels. © 2016 Paul Billiet ODWS

Upside down pyramids of numbers © 2016 Paul Billiet ODWS

Size is a problem Organisms with a high biomass can turn a pyramid of numbers upside down Answer: build a pyramid of biomass Biomass = the total mass of organic matter in organisms in an ecosystem. © 2016 Paul Billiet ODWS

Pyramid of biomass © 2016 Paul Billiet ODWS

Measuring biomass Area delimited and sampled Standard area and sufficient sample size needed Organisms identified and sorted by trophic level Even underground structures/organisms needed It may be necessary to separate tissues from inorganic shells (e.g. molluscs) Tissues of organisms massed (weighed) = Fresh mass Tissues dried to constant mass (80-100°C) = Dry mass Removes water leaving organic matter Destructive sampling © 2016 Paul Billiet ODWS

Upside down pyramids of biomass Trophic level Old field, Georgia / g m-2 English Channel Top carnivores 0.1 Herbivores 0.6 21 Producers 470.0 4 © 2016 Paul Billiet ODWS

Rate of production is a problem As the life cycle of some organisms is faster their turn over is faster Sample at any one time and you find less of the organisms with a fast turn over (e.g. phytoplankton) Energy transfer needs to be measured over a whole growing season. © 2016 Paul Billiet ODWS

The pyramid of energy Cannot be turned upside down Measured as the energy flow per unit area per unit time J m-2 y-1 © 2016 Paul Billiet ODWS

© 2016 Paul Billiet ODWS www.globalchange.umich.edu/.../trophic2.html