Ecosystem Productivity

Principles of Ecology

Primary productivity The rate at which producers capture & store

energy in their tissues Gross = total Net = after respiration The most productive ecosystems in the world estuaries, swamps, marshes, tropical rain forest

Factors influencing primary productivity Climate & nutrients Morphology & size of organism Rainfall Temperature Season Soil (mineral & nutrient availability)

Net primary production per unit area of the world’s common ecosystems

www.globalchange.umich.edu/

Trophic Levels Feeding levels with respect to primary source

of energy Producers & consumers each occupy a

different trophic level Energy is lost at each level

Trophic Levels1st Trophic Level

Producers Plants

2nd Trophic Level Primary Consumers

Herbivores

3rd Trophic Level Secondary Consumers

Carnivores

HEAT HEAT

Decomposer

Biomass Pyramids

1st Trophic LevelProducers Plants

2nd Trophic LevelHerbivores

3rd Trophic LevelCarnivores HEAT

Decomposer

HEAT

Biomass Pyramid The total weight of all living organisms Biomass at each trophic level

biomass pyramid

Biomass pyramid(grams/m2)

809

37

11

1.5

Producers

Herbivores

Primary carnivores

Top carnivores

Detrivores/decomposers5

Biomass Pyramids

1st Trophic LevelProducers Plants

2nd Trophic LevelHerbivores

3rd Trophic LevelCarnivores HEAT

Decomposer

HEAT

Biomass Pyramids

HEAT

Decomposer

HEAT

At each levelsome biomass is not passed

to next higher level

Biomass decreases at higher trophic levels

Not all biomass is consumed from one trophic level to next Not all that is consumed Not all that is consumed is digestible Not all that is digested is turned into mass Part of mass is converted to energy or heat Lost mass is available for decomposition

VegetarianismShorter food chain/web = less loss of energy

Supports idea that vegetarianism is the best way to feed a large population

Results in a decrease of human position on food chain

Will this solve the worldfood problem?

Cellulose most abundant, naturally occuring organic molecule on earth

Humans can’t digest it Ruminants can digest it

Cattle, sheep, goats Deer, bison, antelope, moose, elk

“Hind-gut fermentors” can digest cellulose Horses, rabbits, some rodents

The “Cellulose Solution”

Drawing by Mike Hale

Cellulose