Chapter 3 Ecosystems and Energy

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

Ecology

Ecology “eco” house & “logy” study of The study of interactions among and between

organisms in their abiotic environment

Biotic - living environment Includes all organisms

Abiotic - non living or physical environment Includes living space, sunlight, soil, precipitation,

etc.

Ecology

Ecologists are interested in the levels of life above that of the organism

Ecology Definitions Species

A group of similar organisms whose members freely interbreed

Population A group of organisms of the same species that occupy the

same area at the same time Community

All 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

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

Energy The ability or capacity to do work Chemical, Thermal, Mechanical, Nuclear,

Electrical, and Radiant/Solar

Energy

Energy exists as: Potential energy

(stored energy) Kinetic energy (energy

of motion)

Potential energy is converted to kinetic energy as arrow is released

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)

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

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

Energy Flow

Passage of energy through an ecosystem Producers Primary consumers Secondary consumers Decomposers

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

Food Web

Ecological Pyramids

Graphically represent the relative energy value of each trophic level Large amounts of energy are lost between trophic

levels to heat

Three main types Pyramid of numbers Pyramid of biomass Pyramid of energy

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

Pyramid of Biomass

Illustrates the total biomass at each successive trophic level Biomass: measure

of the total amount of living material

Progressive

reduction in biomass through trophic levels

Pyramid of Energy

Illustrates how much energy is present at each trophic level and how much is transferred to the next level Most energy

dissipates between trophic levels

Explains why there are so few trophic levels

Ecosystem Productivity

Gross Primary Productivity (GPP) Total amount of energy that plants capture and

assimilate in a given period of time

Productivity by Different Ecosystems