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Semester Final Review
Systems
Systems
• Systems are networks of interactions among
interdependent components.
– It is an organized group of related objects or
components that form a whole.
– Systems have
•
•
•
•
boundaries,
components,
resources flow (input and output),
and feedback.
Open Systems
• Systems can be closed,
open, or isolated.
– Open systems
contain matter,
energy, or
information that is
exchanged between
parts of the system
and external
sources.
Closed System
– Closed systems
exchange energy but
not matter (does
not naturally occur).
• Eg.
–
–
–
–
Submarine
Ecosphere
Bioshpere 2
Water and nitrogen
cycles approximate
to closed systems
Isolated Systems
• Isolated systems
– Exchange neither matter nor energy.
– No such system exists (with the possible exception
of the entire cosmos).
Feedback Loops
Positive Feedback Illustrations
• Positive Feedback
graph
• Positive Feedback
Loop
Negative Feedback Illustrations
• Negative Feedback
Graph
• Negative Feedback Loop
Energy For Life
Thermodynamics
• First Law of Thermodynamics
– Energy is conserved—it is neither created nor
destroyed, rather it changes from one form to
another
• Eg. Electrical to heat energy
– Therefore the same amount of the energy that
goes into a system, leaves the system.
Thermodynamics
• Second Law of
Thermodynamics
– With each successive
energy transfer, less
energy is available to do
work.
• The energy is degraded
to lower quality forms or
• It is lost as heat-dissipates
Energy Flow Diagrams
• Show how nutrients are cycled through the ecosystem,
and how much of the energy is “lost” as heat.
Arrow width can
vary to represent
flow quantity,
although this
diagram does not
illustrate this.
Boxes = storages
Yellow arrows =
energy
Blue arrows =
nutrients
Cellular Respiration
• Cellular respiration demonstrates the 2nd Law
of Thermodynamics
Ecology
Biological Pyramids--Productivity
• 10% Rule
– Only about 10 % of the
energy in one consumer
level is represented the
next higher level.
– In other words 90% is
lost.
Productivity
• Productivity is one of the most important
properties of an ecosystem.
– There are 2 kinds of productivity:
• Primary productivity
– Basis for almost all growth in an ecosystem.
» Autotrophs (Photosynthesizers) are responsible for the
primary productivity in an ecosystem.
• Secondary productivity
– The manufacture of biomass (biological material) by
organisms that eat plants.
Primary Productivity and Ecological
Succession
What happens to biodiversity during
ecological succession?
Primary Succession
• Primary succession
begins with a total
lack of organisms
and bare mineral
surfaces (for
example a lava
field) or water.
• There is no gross
productivity.
Secondary Succession
• Secondary succession occurs when an existing
community is disturbed or destroyed (for
example by fire, flood, or human activity) but
much of the soil and some of the organisms
remain.
Terrestrial Primary Succession
• Terrestrial primary
succession
– A pioneer community is a
collection of organisms able
to colonize bare rock (e.g.,
lichens).
• Lichens help break down
rock and accumulate
debris, helping to form a
thin soil layer.
• The soil layer begins to
support small forms of life.
Terrestrial Primary Succession
• Steps to terrestrial primary succession
1.Lichen community replaced by annual plants.
2.Annuals replaced by perennial community.
3.Perennial community replaced by shrubs.
4.Shrubs replaced by shade-intolerant trees.
5.Shade-intolerant trees replaced by shade-tolerant
trees.
6.Stable, complex, climax community
eventually reached.
Terrestrial Primary Succession
Climax Community
• A climax community is a
relatively stable, longlasting community that is
the result of succession.
The kind of climax
community that develops
is primarily determined by
climate and soil type.
– Eg. Pacific Northwest old
growth forest or a desert
Aquatic Primary Succession
• Aquatic primary succession
– Except for oceans, most aquatic systems are
considered temporary.
– All aquatic systems receive inputs of soil particles
and organic matter from surrounding land.
– This results in the gradual filling of shallow bodies
of water.
• Roots and stems below water accumulate more
material.
• Establishment of wet soil.
Primary Succession
Primary succession from a pond to a wet meadow.
***Note the magnitude of the arrows
Carbon
Cycle
for each diagram in this power point.
Carbon cycle
Phosphorus Cycle
Phosphorus cycle
Hydrologic Cycle
Symbiotic Relationships
• Symbiosis is a close, long-lasting, physical
relationship between two different species. At
least one species derives benefit from the
interaction.
• There are five categories of symbiotic
relationships:
–
–
–
–
–
Parasitism +/Commensalism +/0
Predation +/- (see previous slides for definitions)
Herbivory +/- (see previous slides for definitions)
Mutualism +/+
Abiotic vs. Biotic
• Abiotic factors are nonliving
things that influence an
organism.
– Organized into several broad
categories
• Energy
• Nonliving matter
– Minerals
– rocks
– Bodies of water
• Living space
–
–
–
–
Amount
Elevation
Topography
aspect
• Ecological processes
– Climate
» Temperature
» Precipitation
Biotic Factors
• Biotic factors are all forms
of life with which an
organism interacts.
– Organized into several broad
categories
• Plants that carry on
photosynthesis
• Animals that eat other
organisms
• Bacteria and fungi that
cause decay
• Bacteria, viruses, and other
parasitic organisms that
cause disease.
Species
• A species refers to all organisms of the same kind that are
genetically similar enough to breed in nature and produce
live, fertile offspring.
– A Dalmatian and a Chihuahua can produce live, fertile offspring. True
or false?
– A donkey and a horse can produce live, fertile offspring. True or false?
Population and Community
• A population consists of
all the members of a
species living in a given
area at the same time.
– (Eg.???)
• All of the populations of
organisms living and
interacting in a
particular area is a
biological community
Ecosystem
• An ecosystem is
composed of a
biological community
and its physical
environment.
– Pacific Northwest
ecosystem
– Arcata’s constructed
wetland. What are some
abiotic and biotic factors
from the article?
Habitat
• The habitat of an
organism is the
space that the
organism inhabits,
the place where it
lives (its address).
Niche
• The niche of an organism is the functional role
it has in its surroundings (its profession)
– Includes all the ways it affects the organisms with
which it interacts as well as how it modifies its
physical surroundings.
• Eg. Beaver and Dandelion
Food Webs and Trophic Levels
• Trophic level is an
organism’s feeding
status in an
ecosystem.
– Eg. grass is at the
producer level
– Eg. A mouse that
eats the plant is at
the primary
consumer
(organisms that
harness the energy
from producers)
level.
Food Webs and Trophic Levels
• Primary Consumers
– Eat producers
• Secondary Consumers
– Eat primary consumers
• Tertiary Consumers
– Eat secondary consumers
• This picture depicts the
trophic levels within a food
chain (one branch of a
food web)
Food Webs and Trophic Levels
• A food chain is a linked feeding
series—the sequence of
organisms through which energy
and materials are transferred
from one trophic level to the
next.
• Food webs are complex,
interlocking series of individual
food chains in an ecosystem.
– Depending on which chain within
the web is followed, an
organism, for example, may be
considered a primary consumer
or a secondary consumer.
Food Webs
and Trophic
Levels
• Notice that the arrows point
in the direction of the
energy flow. It is not based
on who gets eaten, rather
on who is doing the eating.
• If an ecosystem is in a
steady state equilibrium,
then the recently observed
behavior of the system will
continue into the future
Biomes: Major Types of
Terrestrial Climax Communities
• Two primary abiotic
factors have major
impacts on the kinds of
climax communities
that develop in any
part of the world.
– Temperature
– Patterns of
precipitation.
Biomes: Major Types of
Terrestrial Climax Communities
Biomes of the world
Biodiversity Loss and Extinction
• Biodiversity is a broad term used to describe the
diversity of genes, species, and ecosystems in a
region.
• A number of factors influence diversity:
– Ecological succession
– Habitat diversity
– Complex ecosystems
• Provide stability
– Stable ecosystems are more likely to survive change and thus provide
more biodiversity over a longer period of time.
Measurement of Biodiveristy
• Simpson Diversity Index
– D = N(N-1)
∑ n(n-1)
Where N=total number of organisms
n=number of individuals of different species
Geographic
Isolation
• Speciation
occurs as a result
of the isolation of
populations.
eg. Darwin’s
finches
Biodiversity Hotspots
(Enger pg. 237)
Is there a correlation?
• # of species to go
extinct since 1800
• Human population
since 1800
E.O. Wilson—the father of biodiversity estimates that
27,000 species are currently lost each year.
Biodiversity Loss and Extinction
• Organisms more prone to extinction:
– Organisms in small, restricted areas, such as islands.
• Environmental changes have large effect.
Biodiversity Loss and Extinction
• Organisms more prone to extinction:
– Specialized organisms
• Relying on constancy of a few key factors.
– Eg. Panda’s only eat bamboo
Biodiversity Loss and Extinction
• Organisms more prone
to extinction:
– Organisms at higher
trophic levels.
• Low population sizes and
reproductive rates.
– Eg. Northern spotted
owl baby mortality rate
is 90%!
Biodiversity Loss and Extinction
• Organisms more prone to extinction:
– Species with small, dispersed populations
• Successful breeding is difficult.
Endangered Species Act (ESA)
• In the U.S., the primary action related to the
preservation of biodiversity involved the
passage of the Endangered Species Act (1973).
What Is Being Done to Preserve
Biodiversity?
• The IUCN (International Union for Conservation
of Nature) uses the Red List to determine a
species’ status
– Scientists look at several factors:
•
•
•
•
•
•
•
Population size
Population reduction
Numbers of mature individuals
Geographic range and degree of fragmentation
Quality of habitat
Area of occupancy
Probability of extinction
Politics
• Non-governmental agencies (NGOs)
To Save or Not to Save
Things to consider when deciding on priority
Keystone species—have a major effect on ecological
functions
To Save or Not to Save
• Things to consider
when deciding on
priority
– Indicator species—tied
to specific biotic
communities
To Save or Not to Save
• Things to consider
when deciding on
priority
– Umbrella species—
require large blocks of
undisturbed habitat
Species-Based Approach to Conservation
• A species-based approach
– Species may be chosen based on the concept of
an umbrella species whose requirements are
believed to incorporate the needs of other species
That is, decisions concerning land management,
for example habitat size, distance from other
communities and risk from threatening processes
are based primarily on one species
– Advantage:
• in preserving one species the needs of other species
present are automatically met.
Protected Areas
The IUCN (International Union for the Conservation of Nature) specifies six
categories of protected areas:
• I. Strict nature reserve/wilderness area: protected area managed mainly
for science or wilderness protection
• II. National park: protected area managed mainly for ecosystem protection
and recreation
• III. Natural monument: protected area managed mainly for conservation
of specific natural features
• IV. Habitat/Species Management Area: protected area managed mainly for
conservation through management intervention
• V. Protected Landscape/Seascape: protected area managed mainly for
landscape/seascape protection and recreation.
• VI. Managed Resource Protected Area: protected area managed mainly for
the sustainable use of natural ecosystems.
Threats to Biodiversity
Causes of extinction
Primary Succession
• Primary succession
begins with a total
lack of organisms
and bare mineral
surfaces (for
example a lava
field) or water.
• There is no gross
productivity.
Secondary Succession
• Secondary succession occurs when an existing
community is disturbed or destroyed (for
example by fire, flood, or human activity) but
much of the soil and some of the organisms
remain.
Terrestrial Primary Succession
• Terrestrial primary
succession
– A pioneer community is a
collection of organisms able
to colonize bare rock (e.g.,
lichens).
• Lichens help break down
rock and accumulate
debris, helping to form a
thin soil layer.
• The soil layer begins to
support small forms of life.
Terrestrial Primary Succession
Secondary Terrestrial Succession
Each step in the process is known as a
seral stage, and the sequence of stages is
called a sere.
Secondary succession on land
Climax Communities
• Climax communities show certain characteristics
when compared with successional communities.
– Climax communities maintain species diversity for an
extended period.
– They contain multiple specialized ecological niches.
– They maintain high levels of organism interactions.
– Climax communities recycle nutrients while
maintaining a relatively constant biomass.
Aquatic Primary Succession
• Aquatic primary succession
– Except for oceans, most aquatic systems are
considered temporary.
– All aquatic systems receive inputs of soil particles
and organic matter from surrounding land.
– This results in the gradual filling of shallow bodies
of water.
• Roots and stems below water accumulate more
material.
• Establishment of wet soil.
Primary Succession
Primary succession from a pond to a wet meadow.
• This graph shows how GPP and respiration
differ as ecological succession progress.
Biological Pyramids
• There are 3 kinds of biological pyramids.
– Productivity
– Biomass
– Number
Biological Pyramids--Productivity
• Productivity can be
expressed in terms of a
pyramid because of the 2nd
law of thermodynamics.
– There is less energy available
as you go up the food chain.
• In other words it takes many
oak tree leaves to support
one caterpillar, many
catepillars to support one
bluetit, and many bluetits to
support one sparrowhawk.
Biological Pyramids--Productivity
• 10% Rule
– Only about 10 % of the
energy in one consumer
level is represented the
next higher level.
– In other words 90% is
lost.
Productivity
• Productivity is one of the most important
properties of an ecosystem.
– There are 2 kinds of productivity:
• Primary productivity
– Basis for almost all growth in an ecosystem.
» Autotrophs (Photosynthesizers) are responsible for the
primary productivity in an ecosystem.
• Secondary productivity
– The manufacture of biomass (biological material) by
organisms that eat plants.
Productivity
• Gross productivity is the amount of energy trapped in organic
matter during a specified interval at a given trophic level.
– (Gross means before deduction, for example, gross income which is a
person’s income before taxes are deducted).
• Think TOTAL energy
Productivity
• Net productivity is the amount of energy trapped in
organic matter during a specified interval at a given
trophic level less that lost by the respiration of the
organisms at that level
Productivity Calculations
• Net Primary Productivity can be calculated
from the following equation:
– NPP = GPP – R
• Where NPP = net primary productivity
• GPP = Gross primary productivity
• R = respiratory loss
Productivity Calculations
• Net Secondary Productivity can be calculated
from the following equation:
– NSP = GSP – R
• Where NSP = net secondary productivity
• GSP = food eaten – fecal loss
• R = respiratory loss
Biomagnification
Numbers shown are in
ppm. The amount of DDT
in the bodies of the
organisms increases as we
go from producers to
herbivores to carnivores.
Because DDT is persistent
it builds up in the trophic
levels of the food chain
The biomagnification of DDT.
Soil
Parts of the Earth
Structure of the Earth
Plate Tectonics
• Plate tectonics is the concept that the outer surface of
the Earth is made of large plates of crust and outer
mantle that are slowly moving over the surface of the
liquid outer mantle.
– Heat from the Earth causes the slow movement.
– Plates are pulling apart in some areas, and colliding in
others due to convection cells.
– These building processes are counteracted by
processes tending to make elevated surfaces lower—
i.e.erosion.
Plate Tectonics
• Heat from Earth’s inner
and outer cores is
transferred through
the mantle by a
process called mantle
convection.
– The mantle moves the
plates along with it as it
convects.
Diversity
• Diverse geographic formations lead to ecological
diversity.
• Ecological diversity leads to biological diversity
(biodiversity).
– organisms have adapted (evolved) to live in a certain
geographic region.
• Examples:
–
–
–
–
Artic hare
Deep water fish
Mountain goats
Bison
Soil Composition
The components of soil.
• Carbon cycle
• Nitrogen cycle
Soil System
• Inputs
–
–
–
–
Air
Precipitation
Organic matter (nutrients)
Energy
• Outputs include
– Air
– Uptake by plant and movement
of matter
– Transformations
• Changing of one gas to another
• Weathering
• Transfers
 material is moved around.
Soil Formation—Abiotic Factors
• Chemical weathering
– Chemical alteration of rock
• Causes fragmentation or dissolving
– Examples: Oxidation, slightly acidic rain water
• Mechanical weathering
– Forces that reduce the size of rock particles without
changing the chemical nature of the rock.
– Causes fragmentation
• Examples: include freezing and melting of ice and plants and
animals
Soil Properties
• Soil structure refers to
the way various soil
particles clump together.
– An ideal soil for agricultural
use is loam, which
combines the good
aeration and drainage
properties of large
particles with the nutrient
retention and waterholding ability of clay
particles.
Soil Properties
Soil texture
Soil Properties
Soil Organisms
– Nematodes and earthworms process plant roots and litter.
– Bacteria and fungi typically decompose organic detritus and recycle
nutrients used by plants.
– Bacteria found in soil (called actinomycetes) gives us the antibiotics
streptomycin and tetracycline.
– Insects and algae
– A single gram of soil can contain hundreds of millions of unicellular
organisms.
Soil Profile
Soil Profile
Major soil types–
Make sure you
label the horizon
pictures on your
notes with the
correct ecosystem
Abuses of Soil
• There are 3 main ways that soil is degraded.
– Erosion
– Toxification
– Salinization
Water Erosion
• Water erosion
– caused by exposed soil when native plants are
removed from the site.
• Examples: deforestation, building sites, clearing for
crops.
Wind Erosion
• Wind erosion may not be as evident as water
erosion, but is still serious.
– It is most common in dry, treeless areas.
– Great Plains of North America have had four
serious bouts of wind erosion since European
settlement in the 1800s.
Abuse--Toxification
• Toxification is caused when modern agriculture
sprays toxic chemicals to kill or drive away pests
(insects or weeds).
– Examples are pesticides and herbicides
• have doubled the crop yield.
– Results in:
•
•
•
•
Killing nontarget species
Creating new pests or organisms
Pesticide resistance
Pollution of waterways
Abuse--Salinization
• Salinization is caused by too much irrigation
which leads to waterlogged soil.
– Salinization results in mineral salts accumulating in
the soil (due to the fact that irrigation water
contains some salt).
• This results in leaving behind a crusty layer of salt
– Consequence: Lethal to plants (think osmosis)
Soil Conservation Practices
• Soil Quality Management Components:
– Manage pests and nutrients efficiently.
• Prevents toxification
– Prevent soil compaction.
• Plants don’t grow in compacted soil.
– Diversify cropping systems.
• Keeps nutrients from being drawn out of the soil.
Soil Conservation Practices
• Ways to prevent salinization:
– Don’t over water.
• Use technology like drip irrigation or downward-facing
sprinklers.
Soil Conservation Practices—
Alternative Cultivation
• Contour farming is tilling at right angles to the
slope of the land. Each ridge acts as a small
dam.
– Useful on gentle slopes.
– One of the simplest methods for preventing soil
erosion.
• Strip farming is the practice of alternating
strips of closely sown crops to slow water flow,
and increase water absorption.
Soil Conservation Practices
• Terracing is the practice of constructing level
areas at right angles to the slope to retain
water.
– Good for very steep land.
Undernourishment
Due to poverty
Undernourishment
• In 1960 nearly 60% of the people living in developing
countries were considered chronically
undernourished.
• Today, despite the fact that their population has
doubled over the past 40 years this number has
fallen to less than 15 %.
• How is this possible? Advantage of
fertilizers/pesticides
• What does that say about a change in carrying
capacity?
Malnourishment
anemia
Overnourishment