Download
1 / 11
110 likes | 250 Views
Energy Flows in Ecosystems. Where does all the energy captured by plants go? SBI4U RHSA. About 1% of the sunlight that reaches Earth is captured by plants for photosynthesis.
E N D
Energy Flows in Ecosystems Where does all the energy captured by plants go? SBI4U RHSA
About 1% of the sunlight that reaches Earth is captured by plants for photosynthesis. • By converting light energy to the chemical energy of glucose, plants are able to produce 150-200 billion tonnes of organic material a year. • This net primary productivity or biomass is measured in grams of vegetation per square metre per year (g/m2/a).
ridge.icu.ac.jp/gen-ed/ecosystem-jpgs/world-bioproduction.jpgridge.icu.ac.jp/gen-ed/ecosystem-jpgs/world-bioproduction.jpg
Rule of 10 • From the producer level up through the consumer levels the “Rule of 10” applies. This rule states that only about 10% of the energy consumed is used to build cells or new biomass in the consumer. • The other 90% of the energy consumed is “lost” to cellular respiration, heat, feces, urine or other cell functions. • Thus less biomass is produced at every higher consumer level. • The Rule of 10 does not apply to the biomass of decomposers in an ecosystem.
Pyramids • In most aquatic and terrestial ecosystems pyramids representing numbers of organisms, biomass and energy can be drawn.
Pyramid Exceptions • There are some interesting exceptions to the standard pyramid shape. • Some aquatic ecosystems have an inverted biomass pyramid because the extremely high reproductive rate of the phytoplankton can support a much larger mass of zooplankton. • A deciduous forest, where there is a large amount of biomass in fewer large trees also gives an unusual shape for a pyramid of number of organisms.
