Ecosystems:
Nature’s Answer to a
Perpetual Motion
Machine
Could this
ecosphere be
considered an
“ecosystem”?
I.
Characteristics of an Ecosystem
A. It is the basic unit of Ecology
B. Includes all the interactions of abiotic and biotic
factors
C. Must be “self-perpetuating and self- maintaining”
D. All have similar structures due to the 4
unbreakable laws of physics
II.
A.
The 2 Energy Laws
Law of Conservation of Energy
“Energy can not be created nor destroyed but can
be transformed into different forms”
Turbine
Transformation (Mechanical Energy)
Steam
(Heat Energy)
Transformation
(Chemical Energy)
Fire
Implication:
All ecosystems form
transformable energy
relationships.
Useable Energy
Useable chemical energy
(organic chemical bonds)
passed from one organism
to another
Food Chain
Main Energy Transformers
Usable Energy
Captures “unusable” energy from “inorganic”
sources and transforms energy into useable
organic form
Processing Methods
Unusable Energy
1. Photosynthesis
99%
2. Chemosynthesis 1%
B. 2nd Law of Thermodynamics
“In every energy transformation there is a loss of “usable” energy”
Energy Lost (heat)
Turbine
Implication:
1. As energy is passed
through an ecosystem,
energy is lost.
Transformation (Mechanical Energy)
2. Ecosystem must
have a constant
unlimited energy
source to perpetuate
Steam
(Heat Energy)
Transformation
(Chemical Energy)
Fire
Energy Loss (heat)
This Law Explains why:
1. Measured energy flow through an ecosystem forms an “energy pyramid”
Pyramid of Numbers
May not be the most accurate… Why?
Pyramid of Biomass
2. Food chains tend to be only 4-5 trophic levels
Pyramid of Net Production
10%
10%
10%
6CO2 + 6H2O  C6H12O6 + 6O2
Where does the energy go?
How much energy is transferred from one level to the next?
Important Concepts:
1. Gross Primary Production: The amount of energy the producers convert to food
by photosynthesis. This can be measured in terms of :
a) amount of CO2 taken from the atmosphere
b) amount of C6H12O6 made
c) amount of O2 produced
What parts of the world contribute most to primary productivity?
Slide 19
Secondary Production
Net Primary Production
Gross Primary Production
2. Net Primary Production: The total amount of carbon made available to the consumers.
Net Primary Production = Gross Primary Production
Plant Respiration
Where on the earth does most of the Net Primary Production take place?
Slide 20
3. Secondary Production: The amount of energy converted to actual biomass by a
consumer
4. Limiting Factors: Abiotic or biotic conditions that restrict productivity in an ecosystem.
(influence of)
Temperature, moisture, soil composition, nitrates and phosphates
Slide 17
III. 2 Matter Laws
A. All matter is made of atoms
Implication: All living things require the same basic atoms
NCHOPS > 98%
Ca, K, Na, Fe, Cl, < 2%
B. Matter can not be created nor destroyed
Implication: All living things must “compete” for atoms.
The limited amount of atoms must recycle through an
ecosystem if the ecosystem is self perpetuating
The Major Biogeochemical Cycles:
Water, Carbon/Oxygen, Nitrogen, Phosphorus
Biogeochemical Cycles
Consumers
Producers
Detritivores
Biological Interactions
Nutrients
available to
producers
Abiotic
reservoir
Geochemical Interactions
Geologic
processes
The Water Cycle: Required to make “clean” water available for all living things
Human Impact
1. Air Pollutants
a. Nitrates
b. Sulfates
Condensation
Condensation
Evaporation
Precipitation
Evaporation
Precipitation
Acid Rain
Transpiration
Percolation
Runoff
a. Nitric Acid
b. Sulfuric Acid
Ground Water
Evaporation
Condensation
Percolation
Ground Water
Precipitation
Runoff
Transpiration
The Carbon/Oxygen Cycle: Required for Carbon Building Blocks and Energy
O2 in Atmosphere
CO2 CO
in Atmosphere
2 in
CO2 + H2O  C6H12O6 + O2
Atmosphere
Photosynthesis
Photosynthesis
Cellular
Respiration
C6H12O6 + O2  CO2 + H2O
Combustion
Fossil Fuels
Plant Primary
Producers
Primary
Consumers
Phytoplankton
Primary
Producers
Carbon
compounds in
water
Food Chains
Waste /
Death
Detritus
Detritivores
Decomposition
Anaerobic
Decomposition
1. Global Warming (Green House Effect)
Human Impact
2. Deforestation
Secondary
Consumers
The Nitrogen Cycle: Nitrogen Required for Making Proteins
(N2)
Lightning
Nitrogen in atmosphere
(N2)
Animals
Denitrification
Plants
Food Chains
Waste
Death
Nitrogen-Fixing
bacteria in root
nodules of legumes
Bacteria soil
Nitrogen
Fixing
Assimilation
Decomposers
Nitrates
(bacteria and
(NO3)
fungi)
Nitrification
Ammonification
Nitrifying
Ammonia Ammonium
(NH3)
(NH4+)
Bacteria
Nitrites
(NO2)
Ammonifying Bacteria Nitrifying Bacteria
Human Impact:1. Fertilizers
2. Sewage
Denitrifying
Bacteria
Eutrophication: Overgrowth in lakes
Phosphorus Cycle: Phosphates Required to Make DNA, ATP, Cell
Membranes
Inorganic Phosphate
Weathering of
phosphate
from rocks
Organic
Phosphate
Plants
Geological
uplifting
Animals
Runoff
Food Chains
Decomposition
Algae
Plants
Dissolved
Phosphate
Leaching
Assimilation
Chemical
Precipitation
Phosphate
in soil
Waste
Death
Decomposers
Sedimentation = new
rocks
Human Impact:1. Fertilizers
2. Sewage
Eutrophication: Overgrowth in lakes
Summary of Ecosystems
(Red Arrows)
As Energy flows through
an Ecosystem, energy is:
Lost
_________________
(Blue arrows)
As Matter flows through an
Ecosystem, Matter is:
Recycled
_________________
What are the minimal steps required
to have a functional Ecosystem?
1. Producers: For energy transformation
2. Detritivores/Decomposers: For recycling
The 5 Laws of Ecology
(according to Dr. Barry Commoner)
1.
Everything is connected to everything else
2.
Everything has to go somewhere
3.
There is no such thing as a “free lunch”
4.
Nature know best
5.
The whole is greater then the sum of its parts
Which laws are being ignored with each of the following issues?
1.
Ozone depletion
2.
Biomagnification of DDT
3.
Cultural Eutrophication
4.
Acid rain
5.
Global warming
6.
Smog in cities
7.
Polluted Drinking water
8.
Human Malnutrition
9.
Over Use of Resources
Effect of Limiting Factors in Aquatic Ecosystems
Collection Data Points
(in vitro)
What is the Limiting Factor in this this Ecosystem?
Slide 8
Primary Production of Ecosystems
Different Ecosystems have Different Productivity Capabilities
#1
#2
#2
#1
1. Which ecosystem is the most productive (g/m 2 /yr) ?
2. Which Ecosystem provides the earth with the most primary production?
Slide 7
Regional Annual Net Primary Production For the Earth
Lower
Which Biomes are the Most Productive?
Higher
Slide 8