AP Environmental Science Mr. Grant Lesson 33 Ecosystems © 2011 Pearson Education, Inc. Objectives: • Define the terms gross primary production and net primary production. • Define ecosystems and evaluate how living and nonliving entities interact in ecosystem-level ecology. • Outline the fundamentals of landscape ecology, GIS, and ecological modeling. • Assess ecosystems services and how they benefit our lives. © 2011 Pearson Education, Inc. Define the terms gross primary production and net primary production. Gross Primary Production: The energy that results when autotrophs convert solar energy (sunlight) to energy of chemical bods in sugars through photosynthesis. Autotrophs use a portion of this production to power their own metabolism. Net Primary Production: The energy or biomass that remains in an ecosystem after autotrophs have metabolized enough for their own maintenance through cellular respiration. Net primary production is the energy or biomass available for consumption by heterotrophs. © 2011 Pearson Education, Inc. Define ecosystems and evaluate how living and nonliving entities interact in ecosystem-level ecology. • Ecosystems consist of all organisms and nonliving entities that occur and interact in a particular area at the same time. • Energy flows in one direction through ecosystems, whereas matter is recycled. • Energy is converted to biomass and ecosystems vary in their productivity. • Input of nutrients can boost productivity, but an excess of nutrients can alter ecosystems in ways that cause severe ecological and economic consequences. © 2011 Pearson Education, Inc. Ecosystems • Ecosystem = all organisms and nonliving entities that occur and interact in a particular area at the same time - It includes abiotic and biotic components • Biological entities are tightly intertwined with chemical and physical entities - Through interactions and feedback loops • Ecosystems receive, process and transform inputs of energy - While cycling and recycling matter - Outputs produced include heat, water, wastes © 2011 Pearson Education, Inc. Systems of interacting entities in ecosystems • Energy from the sun flows in one direction - Arriving as radiation and leaving as heat • Matter is recycled within ecosystem - Through food-web relationships and decomposition © 2011 Pearson Education, Inc. Energy is converted to biomass • Primary production = conversion of solar energy to chemical energy in sugars by autotrophs • Gross primary production (GPP) = assimilation of energy by autotrophs • Net primary production (NPP) = energy remaining after respiration which is used to generate biomass - Available for consumption by heterotrophs • Secondary production = biomass generated by heterotrophs from consuming autotrophs • Productivity = rate at which ecosystems generate biomass © 2011 Pearson Education, Inc. Net primary productivity of ecosystems High net primary productivity = ecosystems whose plants rapidly convert solar energy to biomass © 2011 Pearson Education, Inc. NPP variation causes global geographic patterns NPP increases with temperature and precipitation on land, and with light and nutrients in aquatic ecosystems © 2011 Pearson Education, Inc. Nutrients can limit productivity • Nutrients = elements and compounds required for survival that are consumed by organisms • Macronutrients = required in larger amounts - Nitrogen, carbon, phosphorus • Micronutrients = nutrients needed in smaller amounts • Nutrients stimulate plant production - Nitrogen and phosphorus are important for plant and algal growth Dramatic growth of algae in water treated with phosphate © 2011 Pearson Education, Inc. Nutrient runoff is devastating aquatic systems • Nitrogen is the more important limiting factor for primary productivity - In coastal ocean waters - Iron is an effective nutrient for open ocean waters • Satellite imagery gives scientists an improved view of productivity at regional and global scales Phytoplankton blooms off the Louisiana coast © 2011 Pearson Education, Inc. Worldwide marine dead zones • Over 400 dead zones occur globally - Most are off the coasts of Europe and the U.S. - Mostly due to farm, city and industrial pollution - Some are seasonal, others are permanent • Fisheries and ecosystems are devastated - Causing over $2 billion/year in lost harvests © 2011 Pearson Education, Inc. Ecosystems interact spatially • Ecosystems vary greatly in size - From a puddle of water to a bay, lake or forest • The term “ecosystem” is most often applied to selfcontained systems of moderate geographic extent • Adjacent ecosystems may share components and interact - I.e. prairie and forests interact where they converge • Ecotones = transitional zones between two ecosystems - Elements of each ecosystem mix © 2011 Pearson Education, Inc. Outline the fundamentals of landscape ecology. • Landscape ecology studies how landscape structure influences organisms. • Landscapes consist of patches spatially arrayed in a mosaic. Organisms dependent on certain types of patches may occur in metapopulations. • Remote sensing technology and GIS are assisting the use of landscape ecology in conservation and regional planning. © 2011 Pearson Education, Inc. Remote sensing applies landscape ecology • Remote sensing allows scientists to take a landscape perspective • Geographic information system (GIS) = computer software used in landscape ecology research - Analyzes how elements of a landscape are arranged - Helps in planning and land-use decisions © 2011 Pearson Education, Inc. Modeling helps us understand systems • A model = a simplified representation of a complex natural process - Helps us understand the process and make predictions • Ecological modeling = constructs and tests models - To explain and predict how ecological systems work • Researchers gather data and form a hypothesis about relationships - Models predict how the system will behave - New data refine and increase the model’s accuracy © 2011 Pearson Education, Inc. Ecological modeling Ecological modeling resembles the scientific method © 2011 Pearson Education, Inc. Assess Ecosystem services and how they benefit our lives. • Ecosystems provide “goods” we know as natural resources. • Ecological processes naturally provide services that we can depend on for everyday living. © 2011 Pearson Education, Inc. Ecosystems provide vital services • Human society depends on healthy, functioning ecosystems - They provide goods and services we need to survive • Ecosystem services = provided by the planet’s systems - Soil formation, water and air purification, pollination - Breakdown of some pollutants and waste - Quality of life issues (inspiration, spiritual renewal) - Nutrient cycling © 2011 Pearson Education, Inc. Ecosystem goods and services © 2011 Pearson Education, Inc.