Ecosystems: What Are They and How Do They Work? Chapter 3

Key Concepts PART 1: Ecology: Earth and ecosystems Energy flows PART 2: Matter cycles Studying ecosystems and human impacts

W HAT KEEPS US AND OTHER ORGANISMS ALIVE ? Section 3-1 PART 1 (Sections 1 through 3)

Ecology Ecology is the study of connections in nature. ABC’s: A= Abiotic (Non-living) B= Biotic (Living) C= Cultural (Human Interactions)

Earth’s life-support system has four major components The atmosphere is the thin membrane of air around the planet. - The troposphere is the air layer about 4–11 miles above sea level. It contains greenhouse gases that absorb and release energy which warms the inner layer of the atmosphere. - The stratosphere lies above the troposphere between 11–31 miles; it filters out the sun’s harmful radiation. The hydrosphere consists of earth’s water, found in liquid water, ice, and water vapor. The geosphere is the hot core, a thick mantle, and thin crust (lithosphere). The biosphere includes parts of the atmosphere, hydrosphere, and geosphere. All parts are interconnected!

Flow of Solar Energy to and from the Earth Greenhouse gases water vapor, CO 2, N 2 O, CH 4, O 3 Greenhouse effect- Heat trapped in the troposphere to warm planet without natural greenhouse effect life would not be possible. 3/animation_media/sun_to_earth/sun_to_earth.html

Earth’s Life-Support Systems (3 interconnected factors) One way flow of high- quality energy Cycling of matter Gravity - holds atmosphere, enables movement of chemicals thru various spheres “Energy flows, nutrients cycle, gravity holds it together.”

W HAT ARE THE MAJOR COMPONENTS OF AN ECOSYSTEM ? Section 3-2

Levels of Organization in the Biosphere Organisms Cells Species Microbes rule! Benefits Include:Decomposition, nutrient cycling, foods, water purification, digestion, antibiotics

Ecosystem structure Ecology focuses on how organisms interact with each other and with their non-living environment: Population is a group of individuals of the same species living in a particular place. Community is populations of different species living in a particular place, and potentially interacting with each other. Ecosystem is a community of different species interacting with one another and with their nonliving environment of matter and energy

Key Living and Nonliving Components of an Ecosystem

Main Structural Components of an Ecosystem gage.com/eart hscience/book _content/ _mil ler/animations/ ch03/animation _media/matter _energy/matter _energy.htmhttp:// gage.com/eart hscience/book _content/ _mil ler/animations/ ch03/animation _media/matter _energy/matter _energy.html

Sun Producers (rooted plants) Producers (phytoplankton) Primary consumers (zooplankton) Secondary consumers (fish) Dissolved chemicals Tertiary consumers (turtles) Sediment Decomposers (bacteria and fungi) Major Components of Freshwater Ecosystems

Trophic levels Every organism belongs to a particular trophic level depending on its source of nutrients. Producers, or autotrophs, use photosynthesis to make nutrients from components in the environment. Consumers, or heterotrophs, get their nutrients by feeding on other organisms or their remains. Consumers can be herbivores (feed on plants), carnivores (feed on animals) or omnivores (feed on both plants and animals).

Producers

Consumers

Trophic levels, continued Consumers can be primary, secondary or tertiary consumers, depending upon their trophic level. Decomposers (bacteria/fungi) break down organic detritus into simpler inorganic compounds. Detritivores (detritus feeders) feed on waste or dead bodies. Producers, consumers and decomposers utilize chemical energy stored in organic molecules. In most cells, this energy is released by aerobic respiration: glucose + oxygen = carbon dioxide + water + ENERGY

Detritivores

W HAT HAPPENS TO ENERGY IN AN ECOSYSTEM ? Section 3-3

Energy flows through ecosystems in food chains and food webs A food chain is a sequence of organisms, each of which serves as a source of nutrients and energy for the next organisms. Organisms are assigned to trophic levels in a food chain.

Energy flows through ecosystems in food chains and food webs A food web is a series of interconnected food chains. Food webs occur in most ecosystems. Organisms are also assigned to trophic levels in food webs. Producers are the first level. Primary consumers are the second. Secondary consumers belong to the third. Tertiary consumers are the fourth (top) level. Detritivores and decomposers process detritus from all trophic levels.

Energy Flow in an Ecosystem There is less high-quality energy available to organisms at each succeeding feeding level because about 90% the energy is lost as heat Ecological efficiency = % of usable energy transferred as biomass from one trophic level to the next (2% - 40%)10% Rule-assumes 10% ecological efficiency Ecological Pyramids- 3 Types 1. Pyramid of Numbers 2. Pyramid of Biomass 3. Pyramid of Energy Flow

Fig. 3-18, p. 49 Secondary consumers (perch) ,000 10,000 Heat Producers (phytoplankton ) Tertiary consumers (human) Primary consumers (zooplankton ) Ecological Pyramids (3 Types) Decomposers Numbers and Biomass Energy Usable energy available at each tropic level (in kilocalories)

Pyramid of Energy Flow

Biomass Productivity The rate of an ecosystem’s producers converting energy into biomass is the gross primary productivity (GPP). Some of the biomass must be used for the producers’ own respiration! Net primary productivity (NPP) = GPP – energy used NPP measures how fast producers can provide biomass and support consumers in an ecosystem. The three most productive systems: swamps & marshes (wetlands), tropical rain forests, estruaries The three least productive:tundra, desert scrub, extreme desert

Fig. 3-19, p. 49 Energy lost and unavailable to consumers Respiration Growth and reproduction Sun Photosynthesis Gross primary production Net primary production (energy available to consumers) Differences between GPP and NPP

NPP in Major Life Zones and Ecosystems

Three Big Ideas PART 1: Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity. PART 2: Some organisms produce the nutrients they need, some survive by consuming other organisms, and others recycle nutrients back to producers. Human activities are altering the flow of energy through food chains and webs, and the cycling of nutrients within ecosystems and the biosphere.