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Chapter 17 Notes Section 17-1 “What is an Ecosystem?” Ecosystem: all of the living and nonliving things that interact in a particular area. The organisms in an ecosystem are Biotic Factors (birds, mouse, grass) Non-living things are called abiotic factors. (sunshine, water, oxygen, air temperature) Habitat and Niche Every organism requires food, water, and living space. Habitat: place in the environment where the organism lives. Ecosystems can have a variety of habitats Species: group of similar organisms that can mate to produce fertile offspring. Niche: role in the environment 1. Type of food it eats (prey upon) 2. How it obtains food 3. General behaviors 4. Physical conditions needed for survival and reproduction Energy Roles An organism’s energy role in an ecosystem may be that of a producer, consumer, or decomposer. Producers: (autotrophs) Energy enters an ecosystem as sunlight. Plant, algae, microorganisms capture sunlight through photosynthesis to make food. Consumers: Heterotrophs: organisms that cannot make their own food. Depend on producers for food and energy. 3 types of consumers Herbivores Carnivores Omnivores Eat only plants Eat only meat Eat both plants and animals Ex: deer, rabbits, cattle, Ex. Lions, snakes, spiders Ex. Crows, goats, humans caterpillars Scavenger: carnivore that feeds on dead organisms. Ex. Vultures Decomposers Organisms that bread down wastes and dead organisms and return the raw materials to the environment. 2 Major groups: (1) bacteria (2) fungi return nutrients to the environment Food Chains/ Food Webs Energy from sunlight converts into sugar (glucose) and starch molecules by producers. Energy is transferred to organisms that eat producers. Energy is later transferred to another organism that eats the 1st organism Food webs and food chains represent movement of Energy in the environment. Food Chain (represents path of energy transferred from one organism to another.) Ex. Grass ------- Mouse ----- Hawk (producer) (1st consumer) (2nd consumer) ---- (is eaten by) Food Web Represents overlapping food chains in an ecosystem (refer to page 563 in textbook) Energy Pyramids When an organism eats food, it obtains energy Energy is used to move, grow, reproduce Part of the energy is available to the next level consumer ***Only 10% of the energy contained in one level of the food pyramid is transferred to the next level. 90% of energy is used by the organism in life processes -limits # of consumers of the next level of the pyramid. Section 17-2 Biogeography Different species live in different parts of the world Continental Drift Theory ( approx 225 million years ago) Older theory that suggests all of the continents were once one large land mass “Pangea”. Later, the landmass began to break apart and pieces began to “drift” away from each other. Organisms migrated over the huge landmass. Fossil evidence suggests that landmasses touched. Continental pieces fit together like a jigsaw puzzle Existing mountain ranges align when continents are fit together. Means of Dispersal 1. Wind and Water ; move seeds from one place to another. 2. Organisms: carried seeds and dropped them (birds) Section 17-3 Biomes ( see attached chart) Section 17-4: Succession: Equilibrium in the Ecosystem Community: all of the different organisms that live together in an area Community in an ecosystem is in Equilibrium ( a state of balance, no sudden changes in species populations) Succession - A series of predictable changes that occur in a community over time. Occur after a sudden change in Equilibrium from fires, volcanic eruptions, floods, hurricanes, or human impact ) Primary Succession o May take centuries o Series of changes that occur in an area where no ecosystem previously existed. o Ex. Volcanic eruption where new land is created. Refer to Fig. 23 p 587 1. no soil at first, only barren rock 2. Pioneer species: first species to populate an area a. Lichen b. Mosses 3. Pioneer species weather rocks and add nutrients to the new soil when they die. 4. Plant seeds carried by wind, birds, etc land in soil and begin to grow. Plants will depend on type of biome 5. Trees and shrubs enter the area, small animals start to populate the ecosystem. 6. Changes will continue to occur until equilibrium is established. Secondary Succession o Series of changes that occur after a disturbance in an existing ecosystem. o Ex. Fires o Hurricanes o Tornadoes o Human activities (logging, farming, mining) o Restores the ecosystem if left to do so o May not be exactly the same as before o More rapid recovery than primary succession Refer to text, page 588, Fig 24 Ex. Abandoned Farmland 1. (after 2 years) weeds and wild flowers fill the plowed field 2. (after 5 years) small pine trees populate the field 3. (after 30 years) grown pine forest, new trees develop 4. (after 100 years) full mixed forest