Energy flow through ecosystems
Autotrophs are organisms that use energy from the sun to produce usable forms of energy. Some examples of autotrophs include plants, algae, and some forms of bacteria.
- Photosynthesis is the process by which producers (autotrophs) use solar energy to convert carbon dioxide and water into glucose.
- Solar energy+6H2O+6CO2 => C6H12O6+6O2
- Cellular Respiration is the process by which cells unlock the energy of chemical compounds
- Respiration is performed by all organisms, including producers, whether by anaerobic respiration or aerobic respiration (without or with oxygen, respectively)
- Energy+6H2O+6CO2 <= C6H12O6+6O2
Primary Consumers are consumers that eat producers. Also called herbivores. Examples include zebras, grasshoppers, tadpoles, and zooplankton.
Secondary Consumers are carnivores that eat primary consumers. Examples include lions, hawks, and rattlesnakes.
Tertiary Consumers are carnivores that eat secondary consumers. One example of a tertiary consumer is a bald eagle.
Consumers- Also known as heterotrophs, organisms which are incapable of photosynthesis and therefore incapable of producing their own energy, they must obtain their energy by consuming other organisms.
Producers- Also known as autotrophs, organisms that use solar energy in order to produce usable forms of energy. Producers are plants, algae, and bacteria
Scavengers- An organism that consumes dead animals. One example of a scavenger is a vulture.
Detritivores- An organism that specializes in breaking down dead tissues and waste products into smaller particles. One example of this is a dung beetle.
Decomposers- Fungi and bacteria that convert organic matter into small elements and molecules that can be recycled back into the ecosystem.
- Without scavengers, detritivores, and decomposers, there would be no way of recycling organic matter and the world would be full of dead animals.
There are two types of primary productivity- Gross and Net
Gross Primary Productivity (GPP)- The total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time.
Net Primary Productivity (NPP)- The energy captured by producers in an ecosystem minus the energy producers respire.
Net Primary Productivity = Gross Primary Productivity - respiration by producers
- Net primary productivity is the energy left over after the respiration from producers takes place, and gross primary productivity is the total amount of energy altogether.
Calculating GPP and NPP-
The NPP of ecosystems ranges from 25 to 50 percent of GPP. Of the one percent (on average) of the sun's energy captured by producers, about 60 percent of that is used to fuel the producer's respiration, and the remaining 40 is used to support the producers growth and reproduction.
Some ecosystems are more productive than others. The amount of energy available in an ecosystem determines how much life the ecosystem can support. For example, the amount of sunlight that reaches a lake surface determines how much algae can live in the lake. In turn, the amount of algae determines the number of zooplankton that the lake can support, and the size of the zooplankton population determines how many fish the lake can support. Therefore, the more energy and consuming is happening in an ecosystem, the more productive it will be.
Ecological efficiency- The proportion of consumed energy that can be passed from one trophic level to another.
Most ecosystems in nature operate at about 10 percent efficiency, however ranging anywhere from 5 to 20 percent.