Download Ecology and Energy: Understanding Ecosystems and the Flow of Energy and more Slides Wildlife Ecology in PDF only on Docsity! Chapter 3 Ecosystems and Energy Docsity.com Overview of Chapter 3 • What is Ecology? • The Energy of Life – Laws of Thermodynamics – Photosynthesis and Cellular Respiration • Flow of Energy Through Ecosystems – Producers, Consumers & Decomposers – Ecological Pyramid – Ecosystem Productivity Docsity.com Ecology Definitions • Species – A group of similar organisms whose members freely interbreed • Population – A group of organisms of the same species that occupy that live in the same area at the same time • Community – Al the populations of different species that live and interact in the same area at the same time • Ecosystem – A community and its physical (abiotic) environment • Landscape – Several interacting ecosystems Docsity.com Ecology • Biosphere contains earth’s communities, ecosystems and landscapes, and includes: Atmosphere - gaseous envelope surrounding earth Hydrosphere - earth’s supply of water Lithosphere - soil and rock of the earth’s crust Docsity.com Energy • The ability or capacity to do work • Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below) Docsity.com Laws of Thermodynamics • First Law of Thermodynamics – Energy cannot be created or destroyed; it can change from one form to another • Second Law of Thermodynamics – When energy is converted form one form to another, some of it is degraded to heat – Heat is highly entropic (disorganized) Docsity.com Photosynthesis • Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of sugar molecules 6 CO2 + 12 H2O + radiant energy C6H12O6 + 6 H2O + 6 O2 Docsity.com Cellular Respiration • The process where the chemical energy captured in photosynthesis is released within cells of plants and animals • This energy is then used for biological work C6H12O6 + 6 O2 + 6 H2O 6 CO2 + 12 H2O + energy Docsity.com Food Chains - The Path of Energy Flow • Energy from food passes from one organisms to another based on their Trophic Level – An organisms position in a food chain determined by its feeding relationships • First Trophic Level: Producers • Second Trophic Level: Primary Consumers • Third Tophic Level: Secondary Consumers • Decomposers are present at all trophic levels Docsity.com Ecological Pyramids • Graphically represent the relative energy value of each trophic level – Important feature is that large amount of energy are lost between trophic levels to heat • Three main types – Pyramid of numbers – Pyramid of biomass – Pyramid of energy Docsity.com Pyramid of Numbers • Illustrates the number of organisms at each trophic level Fewer organisms occupy each successive level Does not indicate: biomass of organisms at each level amount of energy transferred between levels Docsity.com Ecosystem Productivity • Gross Primary Productivity (GPP) – Total amount of energy that plants capture and assimilate in a given period of time • Net Primary Productivity (NPP) – Plant growth per unit area per time – Represents the rate at which organic material is actually incorporated into the plant tissue for growth • GPP – cellular respiration = NPP – Only NPP is available as food to organisms Docsity.com Human Impact on NPP • Humans represent 0.5% of land-based biomass, but use 32% of land-based NPP! – This may contribute to loss of species (extinction) • This represents a threat to planet’s ability to support both human and non-human inhabitants Docsity.com
