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Transcript
Chapter 4 Notes Ecosystems Ecosystems • Community – a group of various species that live in the same place. • Ecosystem – includes a community of organisms and their physical environment. Physical Factors • = nonliving factors • Called abiotic factors • Example: oxygen, sunlight, rocks, sand, and water. • Habitat – the place where an organism lives. Biodiversity • The variety of organisms in a given area. • Physical factors have a big influence on biodiversity. -low water sunlight, etc. = less biodiversity. Succession • All ecosystems change. • As the ecosystem changes, the kinds of species that the ecosystems supports changes. • The replacement of one community by another at a single place over a period of time is called succession. Change in a new environment • The first organisms to appear in a newly made habitat are called pioneer species. • Pioneer species are often small, fastgrowing plants that reproduce quickly. Equilibrium • If a major disruption strikes a community, many of the organisms may be wiped out. • An ecosystem responds to change in such a way that the ecosystem is restored to equilibrium. • Sometimes the ecosystem will find and equilibrium in which different species dominate after a change. Major Biological Communities • Terrestrial Biomes – Tropical – Temperate – High-Latitude **Two key factors that determine biomes are temperature and precipitation. Definitions • Climate- the average weather conditions in an area over a long period of time. • Biome – a large region characterized by a specific kind of climate and certain kinds of plants and animal communities. Tropical Biomes • Located at low latitudes near the equator. • All tropical biomes are warm. – Tropical rain forests • Receive large amounts of rain and are warm all year – Savannas • Tropical grasslands • Get less rain than tropical rain forests • Example: eastern Africa(zebras, giraffes, lions and elephants) – Tropical deserts • Get very little rain • Have fewer plants and animals than other biomes Temperate Biomes • Have a wide range of temperatures throughout the year. – Temperate grasslands • Moderate precipitation and cooler temperatures than savannas • Highly productive for agriculture – Temperate forests • Mild climates that receive plenty of rain • Deciduous forest trees shed their leaves in the fall because of cold winter. Evergreen forests do not shed their needles. • Deer, bears, beavers, and raccoons. – Temperate deserts • Receive little precipitation • Have a wide temperature range throughout the year. High-Latitude Biomes • Have cold temperatures. – Taiga • Coniferous forests in cold, wet climates. • Winters are cold and long. Most precipitation falls in the summer. • Wolves, moose, and bears – Tundra • Gets very little rain, so plants are short. • Water is frozen for most of the year. • Foxes, lemmings, owls, and caribous. Aquatic Ecosystems • • • • Freshwater ecosystems Wetlands Estuaries Marine ecosystems Freshwater ecosystems • Bodies of freshwater • Lakes, ponds, rivers, streams • Fish, arthropods, mollusks, and other invertebrates Wetlands • Link between land and fully aquatic habitats. • Contain “water-loving” plants • Supports many species of birds, fishes and plants. Estuaries • Area where fresh water from a river mixes with water from an ocean. • Constantly receive fresh nutrients from the river and the ocean. Marine ecosystem • Found in the salty water of oceans • Kelp forests, seagrass communities, and coral reefs. • Open ocean (far from land) has plankton and large predators (dolphins, whales, and sharks) ENERGY FLOW IN ECOSYSTEMS Trophic levels • • • • Every thing organisms do requires energy. Energy flows through ecosystems. Organisms eat other organisms. The primary source for energy in an ecosystem is the sun. Producers • Photosynthetic organisms that are the basic food source for an ecosystem. Consumers • Organisms that eat other organisms instead of producing their own food. Decomposers • Bacteria and fungi • Organisms that break down the remains of animals. MEMORIZE THIS • In an ecosystem, energy flows from the sun to producers to consumers to decomposers. • Each step is called a trophic level. Assignment • Pg. 97, 2-17. • Pg. 99, 1-9 Loss of Energy • Energy is stored at each link in a food web. • Some energy dissipates(releases) as heat into the environment and is not recycled. The Ten Percent Rule • Only about 10 percent of energy consumed by an organism is kept, the other 90% is given off as heat energy. • A 100 kg lion requires 10000 kg of producer energy to survive. Energy Pyramid • A triangular diagram that shows an ecosystem’s loss of energy, which results as energy passes through an ecosystem’s food chain. • Each layer in an energy pyramid represents one trophic level. • The lowest level has the most energy. The End • We are not going to go through the cycles.