Chapter 11-Agroecosystems PDF

10/27/2014 Chapter 11—Agroecosystems Key Concepts Ecology deals with relationships among organisms and environment Ecosystems provide unique services Agroecosystems are managed to produce food and fiber Simplification of agroecosystems has led to social and ecological disasters A sustainable agricul...

10/27/2014 Chapter 11—Agroecosystems Key Concepts Ecology deals with relationships among organisms and environment Ecosystems provide unique services Agroecosystems are managed to produce food and fiber Simplification of agroecosystems has led to social and ecological disasters A sustainable agriculture will maintain soil and environmental resources for future generations Ecosystems Ecosystems Where organisms and their environments collectively function Processes and characteristics include: – Food chains – Nutrient cycles – Plant succession – Competitive exclusion – Diversity 1 10/27/2014 Ecosystem—Food Chains Reflect the flow of energy and nutrients Plants are primary producers Primary consumers eat producers Secondary consumers eat primary consumers Ecological pyramids describe transfer of energy and biomass - - Nitrogen Nutrient Cycles—Nitrogen www.fossweb.com/resources/pictures/16327852.html Other Ecosystem Characteristics Diversity Diversity—numerous coexisting species that utilize different resources eventually, gets - Competitive exclusion—two species cannot something pushed out simultaneously occupy the same niche think of Plant succession—natural changes in community structure over long periods sharing dorm- 2 10/27/2014 Plant Succession Biomes Unique environments of large natural ecosystems containing specific communities of plants and animals Major biomes of North and South America – Tundra – Forests – Grasslands – Deserts http://www.digitalpencil.or g/projects_Allgrades/aroun dtheworld/biomes/Images/ BiomeOfWorldMap.gif Agroecosystems Systems managed to produce food, fiber, or other agricultural products Types of agroecosystems – Corn‐soybean rotation – Animal‐based agroecosystems 3 10/27/2014 How Do Natural Ecosystems and Agroecosystems Differ? O Diversity Inputs Natural Ecosystems Agroecosystems High Low None High High High High High High None Management Breeding Nutrient loss None None None None None Some Some None Risks of Simplified Agroecosystems Virus wiped all Simplified food chain used in agroecosystems is vulnerable Examples of consequences include out potatoes – Irish potato famine – The Dust Bowl – Global warming – Dead Zone - - www.ers.usda.gov/.../Findings/deadzone.htm & questgarden.com Hypoxice A Sustainable Agriculture Earth's Earth’s resources are not infinite Accountable and profitable production of food, fiber, or energy Need to maintain soil, water, and air resources for future generations Should be profitable for good land stewards 4