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Chapter 53. Ecosystems and the Biosphere. Energy flow through an ecosystem Linear Sun to producer to consumer to decomposer Trophic relationship may be expressed as food chains or as food webs. Energy flow through an ecosystem. Ecological pyramids
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Chapter 53 Ecosystems and the Biosphere
Energy flow through an ecosystem • Linear • Sun to producer to consumer to decomposer • Trophic relationship may be expressed as food chains or as food webs
Ecological pyramids • Express the progressive reduction in numbers of organisms, biomass, and energy found in successive trophic levels
Gross primary productivity (GPP) • Rate at which photosynthesis captures energy • Net primary productivity (NPP) • Energy that remains after plants and other producers carry out cellular respiration
Carbon cycle • Carbon dioxide is the most important gas • Carbon enters plants, etc., as CO2 • Cellular respiration, combustion, and erosion of limestone return CO2 to the environment
Nitrogen cycle • Five steps • Nitrogen fixation • Nitrification • Assimilation • Ammonification • Denitrification
Phosphorus cycle • Phosphorus erodes from rock as inorganic phosphate • Animals obtain it from their diet
Hydrologic cycle • Renews the supply of water • Involves an exchange of water between the land, ocean, atmosphere, and organisms • Water enters the atmosphere by evaporation and transpiration • Water leaves the atmosphere as precipitation
Bottom-up processes • Availability of resources such as nutrient minerals controls the number of producers, which controls the number of herbivores, etc. • Top-down processes • An increase in top predators cascades down the food web
Sunlight primary source of energy • Combination of Earth’s spherical shape and its axis tilt concentrate solar energy at the equator • Inclination of Earth’s axis primarily determines the seasons
Visible light and infrared radiation warm the surface and lower part of the atmosphere • Atmospheric heat produces air movement, which moderates the climate
Coriolis effect • Tendency of moving air or water to be deflected • Right in the Northern Hemisphere • Left in the Southern Hemisphere
Regional precipitation differences • Influenced by latitude, elevation, topography, vegetation, distance from large bodies of water, and location • Precipitation greatest where warm air passes over the ocean and then cools
Effect of fire on certain ecosystems • Fire frees the nutrient minerals locked in organic matter, removes plant cover, and increases erosion • Many ecosystems, such as savanna, chaparral, grasslands, and certain forests, contain fire-adapted organisms