Ecosystems and Energy 3. © 2015 John Wiley & Sons, Inc. All rights reserved. Overview of Chapter 3 What is Ecology? The Energy of Life Laws of Thermodynamics.

Ecosystems and Energy3

© 2015 John Wiley & Sons, Inc. All rights reserved.

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 and Decomposers Path of Energy Flow: Who Eats Whom Ecological Pyramids Ecosystem Productivity


Chesapeake Bay salt marshes

An estuary – semi-enclosed body of water where freshwater drains into ocean Tidal – gradual changed from fresh to salt water

Cordgrass dominates – brackish Home to insects and birds,

nursery for fish Very important buffer for

coasts against storms


Ecology

Ecology “logy” study of, “eco” house – study of one’s house 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

Organisms interact with biotic components, but also effect many physical and chemical processes

Physical – walking on soil

Chemical – CO2, O2, wastes


Ecology

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


Ecology Definitions

Species - A group of similar organisms whose members freely interbreed to produce fertile offspring

Population - A group of organisms of the same species that live in 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 (ex: bear hunting for salmon in a river, living in adjacent forest)


Part of Earth that contains living organisms

Ecology

Community and physical environment

Individuals

Group of same species

All populations of species in an area


Ecology

Coral Reef communities – similar to rainforests for number of species and productivity

Threatened with changing climate How can communities be protected from warming waters?

What could loss mean?


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


Ecology

Lithosphere

Hydrosphere

Atmosphere


Energy of Life

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

Electrical, and Radiant/Solar (below)


Solar radiation is the primary source of energy on planet

Energy of Life

Plants turn solar radiation into food


Energy of Life

Energy exists as: Potential energy

(stored energy) Kinetic energy

(energy of motion)

Potential energy is converted to kinetic energy as arrow is released from bow


Thermodynamics

Study of energy and its transformations System- the object being studied

Closed System- Does not exchange energy with surroundings (rare in nature)

Open System- exchanges energy with surroundings


Laws of Thermodynamics

First Law of Thermodynamics Energy cannot be created or destroyed; it can

change from one form to another

Energy is absorbed by water and plate, but not lost


Laws of Thermodynamics

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)

Water in sunlight will get warmer

Engine converts chemical energy of gasoline into mechanical energy inefficiently


Photosynthesis

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

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

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

Chlorophyll in plants


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

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

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


Photosynthesis and Cellular Respiration


Life without Sun

1970s – discovered hydrothermal vents in deep ocean (200oC or 392oF)

Rich ecosystem supported without light Bacteria perform

chemosynthesis Similar to

photosynthesis, but use chemical (H2S) not sunlight


Energy Flow Through Ecosystems

Passage of energy through an ecosystem


Food Chains- The Path of Energy Flow

Energy from food passes from one organism to another based on their Trophic Level Definition: An organism’s position in a food chain,

which is determined by its feeding relationships First Trophic Level: Producers Second Trophic Level: Primary Consumers Third Trophic Level: Secondary Consumers Decomposers are present at all trophic levels


Food chains

Autotrophs = Producers Auto “self” and tropho “nourishment” Produce own food from inorganic material Ex: plants via photosynthesis and hydrothermal

vent bacteria via chemosynthesis


Food chains

Heterotrophs = Consumers heter “different” and tropho “nourishment” Uses bodies of other organisms as food

Omnivores – eat both plants and animals


Food chains

Consumers of detritus (detritivores) Eat dead material such as leaves, carcasses,

feces Ex: crabs, worms, millipedes, snails


Food chains

Decomposers or saprotrophs sapro “rotten” and tropho “nourishment” Breakdown dead organic material Release inorganic molecules (CO2 and nutrients)

that producers can use Ex: fungus,

bacteria Involved in

all aspects of food chains


Food Web

Food web visualizes feeding relationships within a community More complex

than food chain Still simplified

compared to nature


Humans and Antarctic food web

Base of web is algae, which is eaten by krill

Krill are eaten by many larger organisms Wastes of whales resupply

nutrients for algae and krill Ozone and climate change

are warming area


Ecological Pyramids

Graphically represent the relative energy value of each trophic level Important feature - large amount of energy is lost

as heat between trophic levels 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

~90% reduction in biomass through trophic levels 100 to 10


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 Lost as heat and energy

to maintain each level 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 Cellular respiration (R)

Plants use some energy of GPP to maintain themselves

Plants respire too Net Primary Productivity (NPP)

Productivity after respiration losses are subtracted What is available as food for other organisms


Ecosystem Productivity

GPP is similar to gross pay in paycheck R is similar to taxes NPP is similar to take home pay

Net Primary Productivity

(plant growth per area per time)

Gross Primary Productivity (total photosynthesis per

area per time)

Plant Cellular Respiration

(per area per time)= -


Variation in NPP by Ecosystem

Coral reefs are near tropical rain forests

Humans consume a large amount of global NPP ~30% but we make up

~0.5% of biomass

This represents a threat to planet’s ability to support both human and non-human inhabitants


Energy and Climate Change

Humans use a large portion of global NPP If we use more biomass as energy rather than

fossil fuels, our use of NPP may increase Corn as fuel, wood for heat

How can we balance our needs with other organisms?


ENVIRONEWS

Use of satellite imagery improves biomass estimates of forests Help protect tropic forests in developing countries Developed countries pay to keep forests intact

Need to ground truth satellite models with monitoring data from forest

Ecosystems and Energy 3. © 2015 John Wiley & Sons, Inc. All rights reserved. Overview of Chapter 3 What is Ecology? The Energy of Life Laws of Thermodynamics.

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