Where does the energy in an ecosystem come from?

Transcription

1 Energy in Ecosystems 18.3 Where does the energy in an ecosystem come from? Producers provide the energy for organisms in an ecosystem. The Sun Producers or autotrophs make their own food so, where do producers get their energy from?? Producers make their own food by: Photosynthesis: process where light is converted to energy in the form of glucose Photoautotrophs Chemosynthesis: the use of chemicals to make food Chemoautotrophs Energy flows through Ecosystems from producers to s get their energy from eating living or once-living resources s are also called heterotrophs because they feed on many different things 1

2 s are not all alike. Herbivores eat only plants. Carnivores eat only animals. Omnivores eat both plants and animals. Detritivores eat dead organic matter. Decomposers are detritivores that break down organic matter into simpler compounds. Food Chains & Food Webs carnivore decomposer Food chains and food webs are two types of feeding relationships and model the flow of energy in an ecosystem. A food chain is a model that shows a sequence of feeding relationships. Simple path through an ecosystem A food chain follows the connection between one producer and a single chain of within an ecosystem. A food web contains several food chains. How Many Chains are in this web? An organism may have several feeding relationships in an ecosystem. A food web emphasizes complicated feeding relationships and energy flow in an ecosystem. More realistic model 12 2

3 Specialists are that primarily eat one specific organism or a very small number of organisms. Trophic levels are the nourishment levels in a food chain. 1 st Level - Producers 2 nd Level - Primary are herbivores that eat producers. Generalists are that have a varying diet. 3 rd Level - Secondary are carnivores that eat herbivores. 4 th Level - Tertiary are carnivores that eat secondary. Food Chain Primary Secondary Tertiary 1 st order 2 nd Order 3 rd Order consumer 4 th Order Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains. Producer (trapped sunlight & stored food) 16 Food Web Food Chains Show Available Energy

4 10% Rule Energy flows up the food chain from the lowest trophic level to the highest. Only 10% of the energy is transported from 1 trophic level to the next. Ex. producer primary consumer 10% of the energy is transferred to the consumer while the other 90% is either used by the organism or lost as heat to the atmosphere Pyramid Models Pyramids model the distribution of energy and matter in an ecosystem. 3 Types of pyramids: -energy pyramid -biomass pyramid -pyramid of numbers Energy Pyramid Shows how available energy is distributed among trophic levels in an ecosystem Outward arrows indicate energy lost as heat and waste 10% transfers to next level energy lost energy transferred Energy Pyramid 24 4

5 Biomass Pyramid Compares the biomass of different trophic levels within an ecosystem Biomass: measure of the total dry mass of organisms in a given area tertiary 75 g/m2 secondary primary 150g/m2 675g/m2 25 producers 2000g/m2 Pyramid of Numbers Shows the number of individual organisms at each trophic level in an ecosystem tertiary secondary Changing one factor in an ecosystem can affect many other factors. Biodiversity: variety of life -the more biodiversity in an ecosystem, the more complex it is Keystone species: a species that has an unusually large effect on an ecosystem primary 500,000 producers 5,000, Beavers are a keystone species because they create an ecosystem used by a wide variety of species creation of wetland ecosystem increased waterfowl Population increased fish population keystone species nesting sites for birds 29 5