Download Environmental Science Chapter 4a 2005-06

Chapter 4: Ecosystems:
Components, Energy Flow and
Matter Cycling
I. What is Ecology?
• The Study of how
Organisms interact with
one another…
and
• How they interact with
their non-living
environment
Organization on the Planet
• Ecosystem Organization:
1. Organism:
• Any Living thing
2. Population:
• Group of interacting
Individuals of the same
species
Biosphere
Ecosystems
Communities
Populations
Organisms
Fig. 4.2, p. 72
3. Community:
• Populations of all the different
species occupy a particular
place
4. Ecosystem:
• Community of different species
interacting with one another
5. Biosphere:
• All of the Earth’s Ecosystems
II. Biomes and Aquatic Life Systems
A. Biomes:
Land portion of the biosphere
Distinct climate and specific life-forms
adapted for life within that climate.
Climate - long-term patterns of weather is
the primary factor determining the type
of life
B. Aquatic life zones:
Marine and Freshwater
Ecosystem Concepts and Components
Coastal chaparral
and scrub
Coastal
mountain
ranges
Sierra
Nevada
Mountain
Desert
Coniferous
forest
Great
American
Desert
Coniferous
forest
Rocky
Mountains
15,000 ft
10,000 ft
5,000 ft
Prairie
grassland
Great
Plains
Deciduous
forest
Mississippi
River Valley
Appalachian
Mountains
Average annual precipitaion
100-125 cm (40-50 in.)
75-100 cm (30-40 in.)
50-75 cm (20-30 in.)
25-50 cm (10-20 in.)
Fig. 4.9, p. 76
below 25 cm (0-10 in.)
C. Ecotone
• Transitional zone between two
ecosystems
• A mixture of species found in both
ecosystems as well as organisms
that are unique to the ecotones.
Ecosystem Boundaries: Ecotones
Land zone
Transition zone
Number
of species
Species in land zone
Species in aquatic zone
Species in transition
zone only
Fig. 4.10, p. 77
Aquatic zone
III. COMPONENTS OF AN ECOSYSTEM
1. ABIOTIC –
• Non-living components
(Water, air, nutrients and solar
energy)
2. BIOTIC –
• Living components
(Plants, animals, microorganisms)
1. Abiotic Ecological Factors
-Each population within an
ecosystem has a RANGE OF
TOLERANCE to abiotic
factors
Lower limit
of tolerance
Few
organisms
Abundance of organisms
Few
organisms
No
organisms
Population size
No
organisms
Upper limit
of tolerance
Zone of
Zone of
intolerance physiological stress
Low
Optimum range
Temperature
Zone of
Zone of
physiological stress intolerance
High
A. Range of Tolerance:
Minimum and maximum Range in
which physical and chemical
variations can be tolerated
• Individuals in a population may
have different levels of tolerance
• Due to genetics, health and age
• Most susceptible during juvenile
and reproductive stages
B. Limiting Factor
The one factor that is most
important in regulating
population size
Limiting Factor Principle:
Too much or too little of any abiotic
factor can limit a population
ABIOTIC FACTORS
•
•
•
•
•
•
•
Sunlight
Temperature
Precipitation
Wind
Altitude
Fire frequency
Soil
• Water currents
• Dissolved nutrient
concentration
(O,N,P)
• Salinity
• Suspended solids
2. Main BIOTIC factors within an
ecosystem
-All the living organisms sustain their
existence by the process of
METABOLISM.
-2 Options:
A. PRODUCERS – AUTOTROPHS
B. CONSUMERS - HETEROTROPHS
A. AUTOTROPHS
-Organisms that have the
ability to make their own
food
PHOTOSYNTHESIS
CHEMOSYNTHESIS
B. HETEROTROPHS
Organisms that have to get their food
from other sources.
 Primary consumer: (herbivore)
 Secondary/Tertiary consumer:
(carnivore)
Omnivore: Plants and Animals
3
2 Consumer
1 consumer
Producer
Detritivores and scavengers: Parts
of dead organisms or their
wastes
Decomposers: Breakdown dead
material (recycle)
AEROBIC RESPIRATION
• Process of using Oxygen to
break down glucose
ANAEROBIC RESPIRATION
• Breaking down Glucose
without Oxygen
Producers / Consumers
The Biotic Components of Ecosystems
 Producers
Heat
 Consumers
 Decomposers
Abiotic chemicals
(carbon dioxide,
oxygen, nitrogen,
minerals)
Solar
energy
Heat
Decomposers
(bacteria, fungus)
Heat
Heat
Producers
(plants)
Consumers
(herbivores,
carnivores)
Heat
IV. Ecological Niches and Adaptation
-NICHE:
-The “role” that an organism plays in
an ecosystem
-HABITAT
the actual physical location where a
species lives.
-Two main types of Niches…
A. Generalist
B. Specialist
A. Generalist Species:
• Broad niches
Ex: Flies, cockroaches, mice, rats,
white-tailed deer, raccoons, channel
catfish and humans
B. Specialists:
•Narrow niches
Ex: Spotted Owls,
Giant Panda Bear
Is it better to be a generalist or
a specialist?
Benefits to specialists:
• If conditions are constant there is
fewer competitors
Benefits to generalists:
• Can adapt easier if the conditions
are rapidly changing
Generalist Species vs. Specialist Species
Number of individuals
Niche
separation
Generalist species
with a narrow niche
Niche
breadth
Region of
niche overlap
Resource use
Generalist species
with a broad niche
Fundamental vs. Realized Niche
Fundamental Niche:
• Full potential range of
conditions
Realized Niche:
• Occupies part of the
fundamental niche to avoid
competition
V. ENERGY TRANSFER:
A. Food Chains, Webs, and Trophic
Levels
1. Food Chain –
Sequence of organisms, each of
which is a food source for the next.
*Shows how energy and nutrients
move from one organism to
another through the ecosystem.
2. Food Web-
-A complex network of
interconnecting food chains
showing the relationship of many
organisms within an ecosystem.
3. Energy Pyramid/Trophic Levels-
A step in the transfer of energy
through an ecosystem
The level of a food chain that an
organism occupies.
ENVIRO ENERGY
B. Biomass and Energy Flow
Each level contains a certain amount
of biomass:
The dry weight of all organic matter in
an organism.
1.) Only a small % of what is eaten is
converted into biomass
2.) The amount of usable energy
decreases at each trophic level
First Trophic
Level
Producers
(plants)
Heat
Second Trophic
Level
Primary
consumers
(herbivores)
Heat
Heat
Third Trophic
Level
Secondary
consumers
(carnivores)
Fourth Trophic
Level
Tertiary
consumers
(top carnivores)
Heat
Solar
energy
Heat
Heat
Detritvores
(decomposers and detritus feeders)
Heat
FOOD CHAINS AND WEBS
Ecological Efficiency:
• % of usable energy transferred from
level to level
• Typically 5-20%
Pyramid of Energy Flow Explains why:
1.) So few top carnivores
2.) Why these species are the first to
suffer when there is disruption
3.) Why they are vulnerable to
extinction
Ecological Pyramids
Heat
Heat
Tertiary
consumers
(human)
Decomposers
Heat
10
Secondary
consumers
(perch)
100
1,000
10,000
Usable energy
Available at
Each tropic level
(in kilocalories)
Heat
Primary
consumers
(zooplankton)
Producers
(phytoplankton)
Heat
Pyramids of Biomass
and Numbers
• Storage of biomass at each
level
• Organisms are sorted, dried
and weighed
• Most land ecosystems have a
reduction in biomass at each
level
• There may be more primary
consumers in an open ocean
• Photoplankon is small and is
eaten as soon as it is produced
VI. Primary Productivity of
Ecosystems
Gross primary productivity (GPP)
Net primary productivity (NPP)
Estuaries
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest (taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Lakes and streams
Continental shelf
Open ocean
Tundra (arctic and alpine)
Desert scrub
Extreme desert
Fig. 4.25, p. 88
800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600
Average net primary productivity (kcal/m2/yr)
Gross Primary Productivity (GPP):
Rate that producers convert solar energy into
biomass
Usually greatest in:
• Shallow Waters
• Coral Reefs (abundant light, heat and
nutrients)
• Upwellings (Currents bring up nutrients
from the ocean bottoms)
Least in:
• Deserts
• Open ocean
Net Primary Productivity:
Producers must use some of the total
biomass they produce for respiration
NPP is what is left as available food.
Net Primary Productivity =
Energy stored - Energy used
(Photosynthesis) - (Respiration)
Why Not Use the Most Productive
Regions to Feed the Human Population?
• Most swamp/marsh foods are not fit for
human consumption
• Most of the nutrient of a tropical forest are
stored in the vegetation
• Energy requirements of harvesting food
from the oceans are too high
• It would deplete vital sources of food for
other forms of life and alter the food webs
How much of the Worlds Net
Biomass Do we Use?
• Humans have taken over a degraded
73% of the Earth’s land surface
• Humans use, waste or destroy 40%
of the net primary productivity
• What may happen if the human
population doubles over the next 4050 years?