Chapter 3Chapter 3Ecosystems and EnergyEcosystems and Energy

Overview of Chapter 3Overview of Chapter 3

What is Ecology?What is Ecology? The Energy of LifeThe Energy of Life

Laws of ThermodynamicsLaws of Thermodynamics Photosynthesis and Cellular RespirationPhotosynthesis and Cellular Respiration

Flow of Energy Through EcosystemsFlow of Energy Through Ecosystems Producers, Consumers & DecomposersProducers, Consumers & Decomposers Ecological PyramidEcological Pyramid Ecosystem ProductivityEcosystem Productivity

EcologyEcology

EcologyEcology ““ecoeco”” house & house & ““logylogy”” study of study of The study of interactions among and The study of interactions among and

between organisms and their abiotic between organisms and their abiotic environmentenvironment

Biotic - living environmentBiotic - living environment Includes all organismsIncludes all organisms

Abiotic - non living or physical Abiotic - non living or physical environmentenvironment Includes living space, sunlight, soil, Includes living space, sunlight, soil,

precipitation, etc.precipitation, etc.

EcologyEcology

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

Ecology DefinitionsEcology Definitions SpeciesSpecies

A group of similar organisms whose members freely A group of similar organisms whose members freely interbreedinterbreed

PopulationPopulation A group of organisms of the same species that live A group of organisms of the same species that live

in the same area at the same timein the same area at the same time CommunityCommunity

All the populations of different species that live and All the populations of different species that live and interact in the same area at the same timeinteract in the same area at the same time

EcosystemEcosystem A community and its physical (abiotic) environmentA community and its physical (abiotic) environment

LandscapeLandscape Several interacting ecosystemsSeveral interacting ecosystems

EcologyEcology

Biosphere contains earthBiosphere contains earth’’s communities, s communities, ecosystems and landscapes, and includes:ecosystems and landscapes, and includes: AtmosphereAtmosphere - -

gaseous gaseous envelope envelope surrounding surrounding earthearth

HydrosphereHydrosphere - - earthearth’’s supply of s supply of waterwater

LithosphereLithosphere - soil - soil and rock of the and rock of the earthearth’’s crusts crust

EnergyEnergy

The ability or capacity to do workThe ability or capacity to do work Chemical, Thermal, Mechanical, Chemical, Thermal, Mechanical,

Nuclear, Electrical, and Radiant/Solar Nuclear, Electrical, and Radiant/Solar (below)(below)

EnergyEnergy

Energy exists as:Energy exists as: Potential energy Potential energy

(stored energy) (stored energy) Kinetic energy Kinetic energy

(energy of motion)(energy of motion) Potential energy is Potential energy is

converted to converted to kinetic energy as kinetic energy as arrow is releasedarrow is released

ThermodynamicsThermodynamics

Study of energy and its Study of energy and its transformationstransformations

System- the object being studiedSystem- the object being studied Closed System - Closed System - Does not Does not exchange energy exchange energy with surroundings with surroundings (rare in nature)(rare in nature)

Open System - Open System - exchanges energy exchanges energy with surroundingswith surroundings

Laws of ThermodynamicsLaws of Thermodynamics

First Law of ThermodynamicsFirst Law of Thermodynamics Energy cannot be created or destroyed; Energy cannot be created or destroyed;

it can change from one form to anotherit can change from one form to another

Second Law of ThermodynamicsSecond Law of Thermodynamics When energy is converted from one When energy is converted from one

form to another, some of it is degraded form to another, some of it is degraded to heatto heat

Heat is highly entropic (disorganized)Heat is highly entropic (disorganized)

PhotosynthesisPhotosynthesis

Biological process by which energy from Biological process by which energy from the sun (radiant energy) is transformed the sun (radiant energy) is transformed into chemical energy of sugar moleculesinto chemical energy of sugar molecules

6 CO6 CO2 2 + 12 H+ 12 H22O + radiant energyO + radiant energy

CC66HH1212OO66 + 6 H + 6 H22O + 6 OO + 6 O22

Cellular RespirationCellular Respiration

The process where the chemical The process where the chemical energy captured in photosynthesis is energy captured in photosynthesis is released within cells of plants and released within cells of plants and animalsanimals

This energy is then used for This energy is then used for biological workbiological work

CC66HH1212OO66 + 6 + 6 OO2 2 + 6 H+ 6 H22OO

6 CO6 CO22 + 12 H + 12 H22O + energyO + energy

Photosynthesis and Cellular Photosynthesis and Cellular RespirationRespiration

Energy FlowEnergy Flow

Passage of energy through an Passage of energy through an ecosystemecosystem ProducersProducers Primary consumersPrimary consumers Secondary consumersSecondary consumers DecomposersDecomposers

Food Chains - The Path of Energy Food Chains - The Path of Energy FlowFlow Energy from food passes from one Energy from food passes from one

organism to another based on their organism to another based on their Trophic LevelTrophic Level An organism’s position in a food chain An organism’s position in a food chain

determined by its feeding relationshipsdetermined by its feeding relationships First Trophic Level: ProducersFirst Trophic Level: Producers Second Trophic Level: Primary ConsumersSecond Trophic Level: Primary Consumers Third Trophic Level: Secondary Third Trophic Level: Secondary

ConsumersConsumers Decomposers are present at all trophic Decomposers are present at all trophic

levelslevels

Food WebFood Web

Ecological PyramidsEcological Pyramids

Graphically represent the relative Graphically represent the relative energy value of each trophic levelenergy value of each trophic level Important feature is that large amounts Important feature is that large amounts

of energy are lost between trophic levels of energy are lost between trophic levels to heatto heat

Three main typesThree main types Pyramid of numbersPyramid of numbers Pyramid of biomassPyramid of biomass Pyramid of energyPyramid of energy

Pyramid of NumbersPyramid of Numbers

Illustrates the number of organisms at Illustrates the number of organisms at each trophic leveleach trophic level Fewer organisms Fewer organisms

occupy each occupy each successive levelsuccessive level

Does not indicate:Does not indicate: biomass of biomass of

organisms at each organisms at each levellevel

amount of energy amount of energy transferred transferred between levelsbetween levels

Pyramid of BiomassPyramid of Biomass

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

measure of the measure of the total amt of total amt of living materialliving material

Progressive Progressive reduction in reduction in biomass biomass through trophic through trophic levelslevels

Pyramid of EnergyPyramid of Energy

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

dissipates dissipates between trophic between trophic levelslevels

Explains why Explains why there are so few there are so few trophic levelstrophic levels

Ecosystem ProductivityEcosystem Productivity

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

and assimilate in a given period of timeand assimilate in a given period of time Net Primary Productivity (NPP)Net Primary Productivity (NPP)

Plant growth per unit area per timePlant growth per unit area per time Represents the rate at which organic Represents the rate at which organic

material is actually incorporated into the material is actually incorporated into the plant tissue for growthplant tissue for growth

GPP – cellular respiration = NPPGPP – cellular respiration = NPP Only NPP is available as food to organismsOnly NPP is available as food to organisms

Variation in NPP by Variation in NPP by EcosystemEcosystem

Human Impact on NPPHuman Impact on NPP

Humans represent 0.5% of land-Humans represent 0.5% of land-based biomass, but use 32% of land-based biomass, but use 32% of land-based NPP!based NPP! This may contribute to loss of species This may contribute to loss of species

(extinction)(extinction) This represents a threat to planetThis represents a threat to planet’’s s

ability to support both human and ability to support both human and non-human inhabitantsnon-human inhabitants