Chapter 5 How Ecosystems Work

 Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules Energy Flow

 This process in which sunlight, carbon dioxide, and water are used by plants, algae and bacteria to make carbohydrates, oxygen, and water  6CO H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O Photosynthesis

 Organisms use carbohydrates to carry out daily activities such as movement, growth, and reproduction Energy Flow

 Organisms that makes its own food  Also known as:  Autotrophs- are at the base of the food chain  Ex. Plants, algae, and some bacteria Producer

 Organisms that get their energy from eating other organisms  Also known as: Heterotrophs Consumers

 Also known as herbivores; these organisms eat autotrophs  Ex. Insects, fish, rabbits, cows Primary Consumers

 Known as carnivores; these organisms eat herbivores  Ex. Chameleon, fish, rats Secondary Consumers

 a carnivore which eats a carnivore which eats a herbivore  Ex. Snake, fish, seal Tertiary Consumer

 eat tertiary consumers; have no natural enemies  Hawks and a shark Quaternary Consumer

 eat both plant and animal (primary consumers and secondary consumers)  Ex. Bears, pigs, and humans Omnivore

 Decomposers eat dead plants and animals to help break down complex compounds into simpler ones.  fungi, bacteria, Decomposers

 By a process called cellular respiration  C 6 H 12 O 6 + 6O 2 = 6CO 2 + 6H 2 O + energy (ATP)  -during cellular respiration cells absorb oxygen and use it to release energy from food occurs within the mitochondria of the cell *So how do organisms use the energy they get?

 A way to visualize this loss of energy from one trophic level is through an:  energy pyramid- with the lowest trophic level on the bottom (pg. 131) Energy Transfer

 Also visualize the transfer of energy through food chains and food webs  also helps us determine which organisms in an ecosystem depend on other organisms to survive Energy Transfer

 a sequence in which energy is transferred from one organism to the next as each organism eats another Food Chain

 shows many feeding relationships that are possible in an ecosystem Food Web

 Decreased amount of energy at each trophic level results in fewer organisms at the higher trophic levels and also limits the number of trophic levels  Only 10% of the energy is available at each level Energy loss

 3 Main Cycles  Carbon Cycle  Nitrogen Cycle  Phosphorus Cycle Cycling of Materials

 Essential for proteins fats and carbohydrates  Carbon enters ecosystem by way of plants; convert carbon dioxide into carbohydrates  Consumers eat the producers and get carbon from the carbohydrates  Some of the carbon is then released back into the air as carbon dioxide  Cycle (pg. 132) Carbon Cycle

 Needed to build proteins  78% of gases in atmosphere  Must be altered or fixed from the atmosphere  Nitrogen-fixing bacteria accomplish this task  Excess nitrogen is released into the soil  Animals get nitrogen by eating plants  Cycle (pg. 134) Nitrogen Cycle

 Needed for bones and teeth  Plants get it from soil and water; absorb through roots  Animals get it by eating plants or from herbivores  Added to soil and water by decomposition  Some washes off the land into the ocean  Some comes from the erosion of rocks  Some from fertilizers  Cycle (pg. 135) Phosphorus Cycle

 A gradual process of change and replacement of the types of species in a community  can take hundreds or thousands of years  each new community that arises often makes it harder for the previous community to survive or the new community will not survive at all Ecological Succession

 Succession that occurs on a surface where no ecosystem has existed before; such as on rocks, cliffs, newly formed islands, sand dunes,  occurs in areas where there is no soil Primary Succession

 Occurs on a surface where an ecosystem has previously existed  occurs in ecosystems that have been disturbed by humans, animals, or by natural processes (fires, volcano’s, etc.)  occurs faster than primary succession Secondary Succession

 Plants that will colonize the area and begin the process of ecological succession  make the new area habitable for other species Pioneer Species

 Over time, pioneer species and other species will continue to grow and inhabit the disturbed ecosystem  Eventually it will form a final and stable community:  Climax community Succession

 Occurs when farmland is abandoned  First pioneer species take over (grasses and weeds)  taller grasses and perennial plants grow in the area (eventually killing the pioneer plants)  over time the taller plants are taken over by taller growing trees  Finally, the land returns to the community that existed before the farmers cleared it for farmland Old Field Succession