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Chapter 4: Ecosystems: Components, Energy Flow, and Matter Cycling “The Earth’s thin film of living matter is sustained by grand-scale cycles of energy and chemical elements.” G. Evelyn Hutchinson What Is Ecology The study of how organisms interact with one another and with their nonliving environment. Connections in nature Important Terminology (Biology Review) Organism Any form of life Cell Eukaryotic cell Prokaryotic cell Species Groups of organisms Population Group of interacting individuals of the same species that occupy a specific area at the same time Genetic Diversity Variance in genetic makeup of populations Habitat Where a population normally lives Levels Of Organization Earth’s Systems Atmosphere Troposphere/Stratosphere Hydrosphere Liquid water Ice, icebergs, frozen soil layers Water vapor Lithosphere Crust and upper mantle Biosphere Where living organisms exist Life On Earth Life depends on three interconnected factors 1. One-way flow of high-quality energy from the sun 2. Cycling of Matter 3. Gravity Interconnected Factors Ecosystem Concepts and Biomes Terrestrial portion of the biosphere has been classified into biomes. These biomes are characterized by: Distinct climate • Long-term patters of weather Specific landforms Characteristics of Ecosystems No distinct boundaries nor self-contained Abiotic Factors Range of tolerance Limiting factor Biotic Factors Producers – autotrophs Consumers - heterotrophs • Herbivores • Omnivores • decomposers Carnivores Scavengers Food Webs and Energy Flow Food Chain Food Web Pyramids of Energy Flow Biogeochemical Cycles Nutrient cycles – the nutrient atoms, ions, and molecules that organisms need to live, grow, and reproduce are continuously cycled from the nonliving environment and then back again. Water Cycle Water Cycle – Human Impacts Withdrawing large quantities of fresh water from streams, lakes, and underground sources. Clearing vegetation from land for agriculture, mining, road and building construction, and other activities. Modifying water quality Carbon Cycle Carbon Cycle – Human Impacts Clearing trees and other plants that absorb CO2 through photosynthesis Adding large amounts of CO2 by burning fossil fuels and wood Nitrogen Cycle Nitrogen Cycle – Human Impacts Adding large amounts of nitric acid into the atmosphere when we burn any fuel. Adding nitrous oxide to the atmosphere through the action of anaerobic bacteria on livestock wastes and commercial inorganic fertilizers Removing nitrogen from topsoil Phosphorous Cycle Phosphorous Cycle – Human Impacts Mining large quantities of phosphate rock for use in commercial inorganic fertilizers and detergents Reducing the available phosphate in tropical forests by removing trees. Adding excess phosphate to aquatic ecosystems: Runoff of animal wastes Runoff of commercial phosphate Discharge of municipal sewage Sulfur Cycle Sulfur Cycle – Human Impact Burning sulfur-containing coal and oil Refining sulfur-containing petroleum Using smelting to convert sulfur compounds of metallic minerals Ecosystem Services “All things come from earth, and to earth they all return. Menander (342-290 B.C.)
