Ecosystems and Energy - Napa Valley College 11… · · 2015-08-22Biosphere contains earth’s...

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



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



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 CO2 + 12 H2O + radiant energy

C6H12O6 + 6 H2O + 6 O2

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

C6H12O6 + 6 O2 + 6 H2O

6 CO2 + 12 H2O + 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



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



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

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Ecosystems and Energy - Napa Valley College 11… · · 2015-08-22Biosphere contains earth’s...

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