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Ecosystems

Ecosystems. Chapter 44. Objectives. Define ecosystem Describe the flow of energy through the ecosystem and define Net Primary Production Define nutrient and describe the flow of nutrients through the ecosystem Be able to discuss how human activities can alter the ecosystem cycles.

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Ecosystems

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  1. Ecosystems Chapter 44

  2. Objectives • Define ecosystem • Describe the flow of energy through the ecosystem and define Net Primary Production • Define nutrient and describe the flow of nutrients through the ecosystem • Be able to discuss how human activities can alter the ecosystem cycles

  3. What Is an Ecosystem? • A community of organisms together with the physical environment in which they live constitutes an ecosystem • Energy, resources and organisms can move between ecosystems.

  4. Chesapeake Bay Ecosystem • Ecosystem defined by the watershed area ~64,000 square miles • Biotic interactions • Predator/Prey • Abiotic (physical) interactions • Light, temperature, nutrients

  5. Energy Capture • Ecosystems capture energy via their producers (trees and aquatic plants) • The amount of energy captured by producers via photosynthesis minus the amount of energy they use is termed Net Primary Productivity • NPP = Total Captured Energy – Energy Used

  6. Energy Flow • Energy captured by producers is lost at each step of the food chain • Continuous flow arriving as sunlight and leaving as heat • How is energy lost? • Not all the available biomass is eaten. • Not all the material eaten can be digested adequately • Much of the ingested material is used for energy or heat

  7. Nutrient Flow • A nutrient is an essential chemical element used by a producer • C, N, P & S • Nutrient quantities are fixed and must be recycled through living and nonliving components of the ecosystem

  8. Human Influence • The actions of humans have disrupted energy flow and nutrient cycles • Loss of producers leads to loss of productivity • Nutrient cycles often sped up as a result of human influence

  9. Ecosystem Process Generation of Soils Control of the Water Cycle Removal of Wastes Energy Flow Nutrient Recycling Human Influence Agricultural practices have exposed soil to the weather resulting in great loss of topsoil. The cutting of forests and other human activities have allowed increased uncontrolled runoff leading to increased erosion and flooding. Untreated sewage wastes and runoff from farms and feedlots have led to increased water pollution. Some industries and nuclear plants have added thermal pollution to the environment.   The release of some gases from the burning of fossil fuels may be slowly increasing the Earth's temperature. (Greenhouse Effect). The use of packaging material which does not break down, burning of refuse, and the placing of materials in landfills prevents the return of some useful materials to the environment. Human Influence on Some Ecosystem Processes

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