ricklefs_lecture_ppt_ch21 - Rick Relyea Robert Ricklefs The...

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The Economy of Nature7th editionLecture PowerPointChapter 21Movement of Elements in EcosystemsRick Relyea · Robert Ricklefs© 2014 by W. H. Freeman and Company
Chapter 21 conceptsThe hydrologic cycle moves many elements through ecosystems.The carbon cycle is closely tied to the movement of energy.The phosphorus cycle moves between land and water.In terrestrial ecosystems, nutrients regenerate in the soil.1245In aquatic ecosystems, nutrients regenerate in the sediments.6Nitrogen cycles through ecosystems in many different forms.3
The hydrologic cycle1Hydrologic cycle: the movement of water through ecosystems and atmosphere; includes evaporation, transpiration, and precipitation.
The hydrologic cycle1Water is involved in many chemical transformations in living and nonliving components of ecosystems.Ninety-seven percent of water is found in the oceans; the remaining water is in lakes, streams, rivers, wetlands, underground aquifers, and soil.Excess water that falls on land is transported in runoff and groundwater into aquatic systems.
Humans and the hydrologic cycle1Creation of impervious surfaces (e.g., roofing, pavement) reduces the water that enters the soil and increases runoff.Removing plant biomass (e.g., cutting down a forest) decreases evapotranspiration and also increases runoff.Increased runoff causes soil erosion and flooding.Climate change may increase temperatures and evaporation rates, leading to an intensity of rain and snowstorms.
Chapter 21 conceptsThe hydrologic cycle moves many elements through ecosystems.The carbon cycle is closely tied to the movement of energy.The phosphorus cycle moves between land and water.In terrestrial ecosystems, nutrients regenerate in the soil.1245In aquatic ecosystems, nutrients regenerate in the sediments.6Nitrogen cycles through ecosystems in many different forms.3
The carbon cycle2
The carbon cycle2In some oxygen-poor habitats (e.g., swamps), carbon is used for respiration instead of oxygen.For example, some archaea bacteria use methanol:4 CH3OH CO2+ 2 H2O + 3 CH4Methane (CH4) is 72 times more effective as a greenhouse gas than CO2.The precipitation of calcium carbonate (CaCO3) leads to development of rock known as dolomite and limestone.The rate of carbon burial (e.g., as oil) is slow and is offset by rates of carbon release from limestone weathering and volcanic eruptions.
Human impacts on the carbon cycle2Over the past two centuries, extraction and combustion of fossil fuels (e.g., coal, oil, natural gas) has increased to meet energy demands.Combustion of fossil fuels releases CO2into the atmosphere.Measurements atop Mauna Loa on the island of Hawaii indicate a 25% increase in atmospheric CO2between 1958 and 2012.Researchers use ice cores to measure CO2concentrations that were in the atmosphere hundreds of thousands of years ago.

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