Chapter 3: Ecosystems and Energy

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27 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

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Chapter 3: Ecosystems and Energy

Brant Wells

Ecology:

Greek word for house “study of one’s house”



The study of the interactions among organisms and between
organisms and their abiotic environments.

o

The environment consists of two parts…



1. Biotic (living) things



2. Abiotic

(nonliving, or physical) things




There are many levels of biological organizations

o

Biosphere:

The layer of Earth containing all living organisms



Earth’s four realms:



Biosphere
: all other three realms combined



Atmosphere
:

the gaseous envelope surrounding
E
arth



Hydrosphere
: Earth’s supply of water, frozen or
liquid



Lithosphere
: soil and rock of Earth’s crust


o

Landscape:
a spatially heterogeneous region that includes
several interacting ecosystems



Landscape ecology:
a subdiscipline of ecology that
studies e
cological processes that operate over large
areas.

o

Ecosystem:

A community and its physical environment

o

Community:
A natural association that consists of all
populations of species that live and interact together within
an area at the same time

o

Population:

A group of organisms of the same species that
live together in the same area at the same time

o

Species:

A group of similar organisms whose members freely
interbreed with one another in the wild in order to produce
fertile offspring



Example: Elephant=speci
es


Many elephants=population


Elephants, zebras, giraffes=community


African wilderness=ecosystem


Chapter 3: Ecosystems and Energy

Brant Wells

Energy:
The ability to do work




Forms of Energy

o

Chemical:
energy stored in the bonds of molecules

o

Radiant:

energy, such as radio waves, visible light, and X
rays, which is transmitted as electromagnetic waves

o

Solar:

radiant energy from the sun

o

Thermal:

heat energy that flows from an object with a higher
temperature to an object with a lower temperature

o

Mechanical:

energy in the movement of matter

o

Nuclear:

energy found within atomic nuclei

o

Electrical:

energy that flows as charged particles

o

Potential:

en
ergy that is stored

o

Kinetic:

energy that is in motion





The study of energy and its transformations is called
thermodynamics

o

System:
consists of multiple interacting parts enclosed in a
definite boundary that forms a unified whole



The rest of the universe would be considered
surroundings

o

Closed System:
self
-
contained and isolated

does not
exchange energy with its surroundings

o

Open System:

exchanges energy with its surroundings




The First Law of Thermodynamics

o

Defined: energy canno
t be created nor destroyed, although it
can change form one form to another



The
amount of energy on Earth today and Earth 20
billion years ago is exactly the same!!



Photosynthesis is a good example of how this works




The Second Law of Thermodynamics

o

Defin
ed: When energy is converted from one form to another,
some of it is degraded into heat, a less usable form that
disperses into the environment



When energy enters the atmosphere as heat, there is
no way to recapture that energy



Entropy:

a measure of this
disorder or randomness




Photosynthesis and Cellular Respiration

o

Photosynthesis

is the biological process in which light
energy from the sun is captured and transformed into the
chemical energy of carbohydrate (sugar) molecules.



This energy is used to manuf
acture the carbohydrate
glucose (C6 H12 O6) from Carbon Dioxide (CO2) and
Water (H2O)
, with the liberation of oxygen (O2)


6CO
2

+ 12H
2
O + radiant energy


C
6
H
12
O
6

+ 6CO
2


o

The chemical energy that plants store in carbohydrates and
other molecules is released within cells of plants, animals, or
other orgasms through
cellular respiration.


C
6
H
12
O
6

+ 6O
2

+ 6H
2
O


6CO
2

+ 12H
2
O + energy


Chapter 3: Ec
osystems and Energy

Brant Wells

Energy Flow:
The passage of energy in a one
-
way direction through an
ecosystem




Producers, Consumers, and Decomposers

o

Producers,

also called
autotrophs
, manufacture organic
molecules from simple inorganic substances, generally carbo
n
dioxide and water, usually using the energy of sunlight.

o

Consumers
, use the bodies of other organisms as a source
of food energy and bodybuilding materials. Consumers are
also called
heterotrophs
.



Consumers that eat producers are
primary consumers
or
her
bivores.



Secondary Consumers
eat primary consumers,
whereas

tertiary consumers
eat secondary
consumers. Both secondary and tertiary consumers are
carnivores.



Omnivores

eat both plants and animals



Detritus feeders
or
detritivores
consume
detritus
,
organic
matter that includes animal carcass, leaf litter,
and feces.

o

Decomposers
, also called
saprotophs
, are microbial
heterotrophs that break down dead organic material and use
the decomposition products to supply themselves with
energy.





In an ecosystem, energy flow occurs in food chains, in which energy
from food passes from on organism to the next in a sequence.

o

Trophic Level:
An organism’s position in a food chain, which
is determined by its feeding relationships

o

Food Web:

A representa
tion of the interlocking food chains
that connect all organisms in an ecosystem.




Ecological Pyramids

o

Ecological Pyramids
often graphically represent the relative
energy values of each trophic level.



Three types of Pyramids



Pyramid of numbers
: shows the n
umber of
organisms at each trophic level in a given
ecosystem



Pyramid of biomass
: illustrates the total biomass
at each successive trophic level.



Biomass
is a quantitative estimate of the
total mass, or amount, of living material; it
indicates the amount
of fixed energy at a
particular time.



Pyramid of energy
:
illustrates the energy content,
often expressed as kilocalories per square meter
per year, of the biomass of each trophic level




Ecosystem Productivity

o

Gross Primary Productivity (GPP)
: the total amo
unt of
photosynthetic energy that plants capture and assimilate in a
given period

o

Net Primary Productivity (NPP)
: Productivity after
respiration losses are subtracted. That is, NPP is the amount
of biomass found in excess of that broken down by a plant’s
cellular respiration. NPP represents the rate at which this
organic matter is actually incorporated into plant
tissues for
growth.