Part One - General Principles of Ecology
A. General Principles of Ecology
a. Ecology: how organisms interact with one another and with their environment
b. Environment: biotic (other organisms) & abiotic (physical factors)
B. Four levels of ecological organization:
a. Population: a group of individuals of the same species occupying a common
geographical area
b. Community: two or more populations of different species occupying the same
geographical area
c. Ecosystem: A community plus its abiotic factors
d. Biosphere: the portion of the earth that contains living species
C. Ecology of Individuals
a. Physiological ecology
b. Temperature & water balance
c. Light & biological cycles
d. Physiological ecology & conservation
D. Ecology of Populations
a. Population Ecology: the study of how populations interact with their environment
b. Population: a group of individuals of the same species occupying a common
geographical area
c. Habitat: where a species normally lives
d. Characteristics of populations
i.
Population size: the number of individuals making up its gene pool
ii. Population density: the number of individuals per unit of area or volume
iii. Population distribution: the general pattern in which the population
members are dispersed through its habitat
1. Clumped (most common)
2. Uniformly dispersed (rare)
3. Randomly dispersed
iv.
Age structure: relative proportions of individuals of each age
1. Pre-reproductive
2. Reproductive
3. Post-Reproductive
v.
Population size & growth
e. Zero Population Growth: near balance of births and deaths
f. Exponential growth: if birth and death rates of a population remain constant they
can be combined into one variable r = net reproduction per individual per unit of
time (rate of increase)
i.
Population growth can be represented mathematically as: G=rN
1. G=population growth per unit time, r = rate of increase, & N = the
number of individuals
2. As long as per capita birth rates remain above per capita death
rates, a population will grow exponentially - with ever-increasing
rates and short “doubling times”
g. Biotic Potential: the maximum rate of increase under ideal conditions
1. Few populations live under ideal conditions because of limiting
factors
h. Limiting Factor: Any resource that is in short supply
i. Carrying Capacity: the maximum number of individuals of a species or
population a given environment can sustain
i.
Each habitat can only support so many individuals
ii. Limiting Factor populations rarely exhibit Exponential growth curves
iii. Early on populations exhibit very rapid growth but as they near carrying
capacity they level off creating logistic growth
j. Density Dependent: the growth is affected by the density of individuals
i.
Logistic growth is density-dependent
ii. High density and overcrowding put individuals at greater risk of being
killed
iii. Population size & growth may be controlled by density-independent
factors
E. Life History Patterns
a. Different populations have very different age structures that will determine their
growth patterns
b. Age Structure: Proportions of pre-reproductive, reproductive, and postreproductive age individuals in a population
c. The age structure of a population determines its future
d. Population ecologists track cohorts and construct life tables for populations
e. Cohort: A group of individuals born at the same time
f. Life Table: An age-specific death schedule
i.
Often converted to a more palatable survivorship schedule
ii. Predicted life expectancy or survivorship for each age interval
iii. Divide populations into age classes and assign birth rates and mortality
risks to each class
iv.
Absolute population numbers mean very little unless age structure is
known
F. Life History Strategies
a. R-selected organisms: put most of their energy into rapid growth and reproduction
i.
Common of organisms that occupy unpredictable environments
b. K-selected organisms: put most of their energy into growth
i.
Common in stable environments near carrying capacity
G. Ecology of Communities
a. Community: two or more populations of different species occupying the same
geographical area
i.
Community Ecology: the study of how different species interact within
communities
ii. Habitat: the physical place where an organism lives
iii. Niche: the functional role of an organism in a community
1. Potential Niche: What they could do with no competitors or
resource limitations
2. Realized Niche: Part of the fundamental niche that a species
actually occupies in nature
b. Species Interactions
i.
Neutral: two species that don’t interact at all
ii. Commensalism: beneficial to one species but neutral to another
iii. Mutualism: An interaction that is beneficial to both species
iv.
Parasitism: An interaction that benefits one species and is detrimental to
another
v.
Predation: An interaction beneficial to one species and detrimental to
another
c. Competitive Interactions
i.
Competition has negative effects on both competing organisms because it
limits available resources, thus driving evolution.
ii. Types of Competition:
1. Intraspecific: Competition among individuals of the same species
2. Interspecific: Competition between different species
3. Theory of Competitive Exclusion: Species that utilize the same
resources cannot coexist indefinitely
4. Resource Partitioning: Resources are divided permitting species
with similar requirements to use the same resources in different
areas, ways, and/or times
iii. Community Stability
1. Communities are not static gradually changing as the environment
changes, and also changing the environment themselves
iv.
Invasive Species
1. Invasive Species: A species that is not native to a specific location
and has a tendency to spread to a degree believed to cause damage
to the environment, human economy, or human health
a. Can impact nutrient cycling, ecosystem dynamics, energy
transfer, water clarity, and food web composition
H. Ecology of Ecosystems
a. Ecosystem: A community of organisms interacting within a particular physical
environment or a community plus its abiotic factors
i.
Virtually all energy comes from the sun via photoautotrophs, ultimately
being distributed throughout the ecosystem
ii. Autotrophs: Primary Producers
iii. Consumers: All other organisms besides autotrophs
iv.
Herbivores: Consumers which eat plants
v.
Carnivores: Consumers which eat animals
vi.
Omnivores: Organisms that eat both plants and animals
vii.
Decomposers: organisms that obtain their energy by breaking down the
remains or products of organisms
viii. Detritivores: decomposers that eat detritus
a. Detritus: Organic wastes and dead organisms
b. Structure of Ecosystems:
i.
Energy flows through ecosystems via food webs
1. Food Webs: Intricate pathways of energy flow and material
cycling
ii. Ecosystems are arranged by trophic (feeding) levels
1. First Trophic Level: contains the autotrophs which build energycontaining molecules
a. Can also absorb N, P, S, and other molecules necessary for
life
b. They provide an energy-fixation base and a nutrientconcentration base for ecosystems
c. Two Types of autotrophs:
1. Photoautotrophs: Plants and some Protista
2. Chemoautotrophs: Bacteria
2. Second Trophic Level: contains the primary consumers which eat
the primary producers
3. Third Trophic Level: Contains the secondary consumers, primary
carnivores which eat the herbivores
4. Fourth Trophic Level: Contains the tertiary consumers, secondary
carnivores who eat the primary carnivores
5. Linear food chains are rare in nature because the same food
sources may be part of several interwoven food chains, and many
organisms have more than one food source
6. Decomposers play a key role but are often not represented
iii. Food Web - Many food chains in relation to each other
c. Energy Flow through Ecosystems
i.
Gross Primary Productivity: The rate at which the primary producers
capture and store energy per unit time
1. Since the primary producers expend energy during respiration net
primary productivity is considerably lower than gross productivity
ii. Productivity is measured as biomass per unit area per a specific time
interval
1. Biomass: Dry weight of organic matter
iii. Trophic Structure of an ecosystem is represented by an ecological
pyramid, with primary producers at the base and other levels above
iv.
Only about 10% of the energy makes it to the next level because the food
is converted to biomass or used to maintain metabolic functions
1. Takes billions of primary producers to support millions of primary
consumers
v.
An energy pyramid is a more useful way to depict an ecosystem’s trophic
structure’
1. Each block is proportional to the amount of energy it contains
2. Pyramids represent biomass or # of individuals
3. Explains biological magnification
a. Biological Magnification: The tendency for toxic
substances to increase in concentration at progressively
higher levels of the food chain
I. Energy vs. Nutrients
a. Nutrients is cyclic
i.
Cyclic: Biogeochemical cycles
b. Energy flow is one way
c. Biomass and Energy Pyramids
i.
Ecological Succession: a directional, cumulative change in the species that
occupy a given area through time
1. Primary Succession: Start from barren ground
2. Secondary Succession: starts from disturbed areas
a. Pioneer Community: the first organisms to occupy an area
b. Several transitional communities may come and go
c. Climax Community: A stable, self-perpetuating array of
species in equilibrium with one another, and their habitat
will form
ii. Secondary Succession
1. Biodiversity: how much variety of life there is at all levels, from
genes to ecosystem
a. Can be measured in a variety of ways
iii.
iv.
v.
b. Species Richness (Alpha Diversity): the number of
different species within an area
c. Species evenness: the measure of the relative abundances
of species in area
d. Genetic Diversity: the amount of variety in the gene pool of
a population of individuals
e. Functional Diversity: the amount of variety in functional
traits that species possess in the ecosystem
i.
Functional traits: characteristics of an organism that
affect how the organism responds to and/or
influences the functioning of its ecosystem
f. Phylogenetic Diversity: the number of different
evolutionary lineages represented; considers how closely
related these lineages are
i.
A community that only contains a few closely
related species has low phylogenetic diversity
2. Biodiversity is greatest in tropical areas near the equator
a. Tropical areas have more sunlight, more rainfall, longer
growing seasons, stable environments, many vertical
layers, and can support more species
Weather and Climate
1. Biome: A large region of land characterized by the climax
vegetation of the ecosystems within its boundaries
a. Key features are the outcome of temperatures, solids, and
moisture levels
2. Weather: The condition of the atmosphere at any given time
3. Climate: the accumulation of weather events over a long period of
time
a. Climate is dependent on:
i.
Solar Radiation
ii.
Earth’s daily rotation
iii. Earth’s rotation around the sun
iv.
The distribution of continents and oceans
Elevation or Depth of Light Penetration
1. Heat energy from the sun drives weather systems, ultimately
determining the composition of ecosystems
Watershed
1. Watershed or Drainage Basin: an area of land where water from
rain and melting snow or ice drains downhill into a body of water
a. All major terrestrial and aquatic ecosystems are impacted
by what happens in a watershed
b. Watershed surface water management plants reduce
flooding, improve water quality, and enhance stream and
wetland habitation
c. Sources of water pollution include
i.
Point Source Pollution: Pollution from a clearly
identifiable location
ii.
Nonpoint Source Pollution: Pollution that comes
from many different places
d. Sources of pollution are industrial, residential, commercial,
and environmental
e. Types of Pollution may include
i.
Organic Pollution: decomposition of living
organisms and their bi-products
ii.
Inorganic Pollution: dissolved and suspended solids
such as silt, salts, and minerals
iii. Toxic Pollution: Heavy metals and other chemical
compounds that are lethal to organisms
iv.
Thermal Pollution: Typically waste heat from
industrial and power generation processes
J. Overview of Terrestrial Ecosystems:
a. Characteristics of Forests:
i.
Trees dominate biome
ii. Forests cover ⅓ of Earth’s land mass
iii. Forests are the most diverse biotic communities
iv.
Compromise ⅔ of the leaf area of plants
v.
Contain 70% of carbon present in living things
vi.
Their Canopies affect other producers, consumers, decomposers, and other
niches
vii.
Hold potential medicines and thousands of undiscovered species
viii. Human beings bring deforestation, pollution, land use change, and
industrial usage problems
ix. Forest types: depend upon the climate and seasonal rainfall
1. Tropical
2. Temperate or Deciduous
3. Boreal (taiga) or coniferous
b. Characteristics of Taiga (Coniferous or Boreal Forests):
i.
The 2nd largest forest type lies between the Artic and Deciduous Forest
line (50-60 degrees North Latitude)
ii.
The angle of incidence for solar radiation is low and twilight lasts many
hours
iii. Summers are short, moist, and warm while Winters are long, cold, and dry
iv.
Temperature can vary greatly (-60 - 70)
v.
Variable Precipitation
vi.
Thin solids because of glaciers that are acidic from the decomposition of
pine needles
vii.
The absence of earth-churning invertebrates makes soil hard and compact
viii. Fire is a major threat in maintaining the biome
c. Characteristics of Deserts:
i.
Cover ⅕ of the earth’s land surface at low latitudes, but there are some
cold deserts
ii. Have a scarcity of water (less than 10in per year) and intense solar
radiation
iii. Water loss may exceed water gain
iv.
Temperature can be hot in the day and cold at night
v.
Poor soil quality with little organic matter but high mineral content
vi.
When it rails, can cause flooding
vii.
Animals adapt to the desert to withstand or avoid water stress
viii. Deserts are expanding in parts of the world
ix. Types of Deserts:
1. Hot and Dry
2. Semiarid
3. Costal
4. Cold
x. Regions of low, sparse vegetation with minimal rain and humidity, high
temperature, and great daily temperature fluctuations
d. Characteristics of Grasslands or Prairies
i.
The precipitation is too low to support trees but too great for deserts to
form
ii. Grasses are the major producer, most possessing rhizomes, and are wind
pollinated
iii. 6-40in of variable precipitation
iv.
Convection Storms during the summer and general rains and snow in
winter
v.
Solids are fertile, deep, and rich with growing seasons of 120-200 days
vi.
Are generally flat to rolling (cut by streams)
vii.
Fire is a major threat to the biome
viii. The region is dominated by grazing animals
Part Two - Problems Resulting from Human Impacts
A. Environmental Issues
a. Major Environmental Issues
i.
Pollution of Air, Water, and Land
ii. Hazardous Chemicals & Wastes
iii. Land Degradation
iv.
Loss of Biodiversity
v.
Ozone depletion
vi.
Loss of natural and cultural resources
b. Major Causes of Environmental Issues
i.
Rapid population growth, effects of urbanization and industry, and
harvesting practices
ii. Rapid & wasteful use of resources
c. Environmental Impact (I) (depends on three factors)
i.
The number of people (population size, P)
ii. Average number of units of resource each person uses (per capita
consumption, A)
iii. Amount of environmental degradation & pollution produced for each unit
of resource used (destructiveness of the technologies used to provide and
consume resources, T)
iv.
I = P * A * T (environmental impact)
v.
Sustaining the Earth - Learning as much about how the Earth sustains
itself and adapts to ever-changing environmental conditions and
integrating lessons from nature into the ways we think and act
1. Basic Environmental Beliefs of the world:
a. Nature exists for all
b. There is not always more
c. Some forms of economic growth are environmentally
beneficial and should be encouraged
i.
Some are environmentally harmful and should be
discouraged
d. Success depends on learning to corporate with one another
and with the rest of nature to learn how to work with the
earth
d. Pollution: when harmful materials enter the environment
i.
Sources of pollution are one of four main categories: industrial,
residential, commercial, or environmental
ii. Pollutants can enter the environment through natural or human activities
iii. Sources of pollution:
1. Point Source Pollution: Pollution from a clearly identifiable
location
2. Non-Point Source pollution: Pollution that comes from many
different places
3. Organic Pollution: The decomposition of living organisms and
their bi-products
4. Inorganic Pollution: Dissolved and suspended solids
5. Toxic Pollution: Heavy metals and other chemical compounds that
are lethal to organisms
6. Thermal Pollution: Waste heat from industrial and power
generation processes
7. Nuclear Pollution: Radioactive materials
e. Harmful Impacts of Pollution - three factors determine the severity
i.
Chemical Nature: how active and harmful the pollutant is to living
organisms
ii. Concentration: The amount of pollutant per unit of volume
iii. Persistence (degradability): How long the pollutant stays in the air, water,
soil, or body of the organisms
iv.
Pollution can affect all areas of the environment
1. Air Pollution: The emission of any impurity into the air, such as
smoke, dust, cinders, solid particles, gasses, mists, fumes, odors,
and radioactive substances
2. Water Pollution: Pollutants being added to ground water, surface
water environments and marine water environments
3. Thermal Pollution: Changes in water temperature due to additions
of hot or cold water to a natural water system
a. Often heated water from cooling at power plants
4. Soil Pollution: Pollutants being added to soil by agricultural
runoffs, unclean technology, and waste disposal
5. Noise Pollution: Excess noise from industrial and urbanization
activities
6. Light Pollution: excess night lighting around urban areas which
can impact the life cycles of organisms
7. Radioactive Pollution: radioactive waste and nuclear accidents
B. Types of Water Pollution and their Effects
Type of
Water
Pollution
Cause of
Pollution
Symptoms of
Pollution
Effect of
Pollution
Source of
Pollution
Biodegradabl
e waste
Humans and
Animals
Decreasing
aquatic life,
increasing
bacteria
Decreasing
aquatic life,
increasing
bacteria
Run-off
Nutrients
Nitrates and
Phosphates
Green,
Algae blooms
cloudy, slimy,
stinky water
Fertilizer runoff, improper
disposal,
wastewater
treatment
Heat
Increased
Water
Temperature
Warmer
water, less
oxygen fewer
aquatic life
Decrease in
oxygen
levels, death
of aquatic life
Industrial runoff,
wastewater
treatment
Sedimentatio
n
Suspended
particles
settling out of
water
Cloudy water,
increased
amount of
bottom
Warmer
water,
decreases
water depth,
deposits
toxins
Construction,
farming,
logging,
flooding, runoff, dams
Chemicals
Toxic and
Hazardous
chemicals
Water color
changes,
odor, aquatic
life dies out
Kills aquatic
life, enters
human food
chain, birth
defects,
infertility,
cancer, etc
Humanmadeimprope
r disposal,
run-off, acid
rain
Radioactive
Pollutants
Radioactive
isotopes
Increased
birth defects
and cancer
Kills aquatic
species, leads
to cancer and
death
Contaminated
Waste water
discharge
Medical
Medicines,
antibiotics
Infertility in
aquatic life,
and other
unknown
symptoms
Unknown
Human
dumping
medicines
into water
systems
C. Aquatic Environment Issues
a. The creation of dams and water-diversion systems blocks migration routes and
disturbs habitats
i.
Dams major factor in water diversion
ii. Built along rivers to produce reservoirs
iii. Affects the ecology of the river and surrounding environments
iv.
Creates Habitat Loss, Habitat Fragmentation, and Loss of Biodiversity
b. Water withdrawal shrinks and degrades habitats
c. Runoff from agricultural and urban areas can hurt water quality
d. Overexploitation & pollution threaten groundwater
e. Exotic species can harm native organisms
f. Global warming leads to devastating floods and droughts
g. Thermal Pollution and Rising Ocean Temperatures
i.
Change in water temperatures caused by man-made industries
ii. Water as coolant is warmed and returned to a body of water
iii. Ocean warming can lead to problems such as coral bleaching
h. Nutrient Overflows
i.
Natural or unnatural disruptions of nutrient flows can lead to elevated
levels of nutrients entering a system
ii. Eutrophication: bodies of water become enriched with nutrients
1. Can cause algal blooms
2. Run-off from fertilizers causes an increase in levels
3. Causes phytoplankton to grow and reproduce more rapidly
4. Bloom disrupts the normal ecosystem and causes problems
5. Algae may use up all the oxygen
6. Bloom can block sunlight from photosynthetic marine plants
7. Algae can produce toxins harmful to higher forms of life causing
problems along the food chain
iii. Sewer Overflows
iv.
This can be due to a lack of infrastructure, old infrastructure overwhelmed
by increased water loads, combined systems, and poor maintenance
v.
Can result in raw sewage going into source
vi.
Increase in rainfall stresses systems
i. Threats to Marine Environments
i.
Ocean Dead Zones
1. Eutrophication magnified as rivers leads into larger rivers
2. Leads to ocean dead zones or regions where hypoxia is present
3. Mississippi river dumps high-nutrient runoff such as nitrogen and
phosphorus into the Gulf (the largest dead zone in the US)
ii. Oil Spills
1. Causes major environmental problems
iii.
iv.
v.
vi.
Marine dumping of wastes
Climate Change
Sea Temperature RIse
Ocean Acidification
1. Caused by excess carbon dioxide dissolving to form carbonic acid,
potentially dissolving the skeletons and shells of marine creatures
vii.
Habitat Loss
1. Loss of mangroves and estuary regions causing population
displacement
viii. Bycatch
1. Unintentionally caught marine life
ix. Whaling
x. Fishery
xi. Overfishing and Exploitation
1. Depletes stocks of fish, disrupting the ecosystem and eliminating a
valuable source of food and income
2. Fish catch has risen from 20-90 million tons per year
3. The original fishing limit was 12 miles out to sea
a. Changed to 200 in the 1960s due to a lack of fish
b. Driftnets: dragged through the water indiscriminately
catching everything
c. Bottom Trawling: Ocean floor is scraped by heavy nets for
all bottom-dwelling fish- leaving a path of destruction
xii. Invasive Species
j. Threat to Estuaries
i.
Receive the pollutants dumped into streams
ii. Development only adds to pollution and eliminates some estuaries due to
landfilling
iii. One of the most threatened ecosystems on Earth
k. Threats to Coral Reefs
i.
CHemical Pollutants
ii. Excess nutrients
iii. Sedimentation
iv.
Coral Bleaching
v.
Coral Diseases
vi.
Climate change & Ocean acidification
vii.
Overfishing
D. Air Pollution Issues
a. Climate Change
i.
Sea level rise
b.
c.
d.
e.
f.
g.
h.
ii. Temperature
iii. Precipitation
Health Impacts
i.
Weather-related illness and mortality
ii. Infectious Diseases
iii. Air Quality- Respiratory and Cardiac Illnesses
Agriculture Impacts
i.
Crop yields
ii. Irrigation demands
iii. Increased GHG
Water Resource Impacts
i.
Changes in water supply
ii. Water quality
iii. Increased competition for water
Impacts on Coastal Areas
i.
Erosion of beaches
ii. Inundate coastal lands
Species and Natural Areas
i.
Shift in ecological zones
ii. Loss of Habitat and species
Atmospheric Deposition: Process, whereby precipitation, particles, aerosols, and
gasses move from the atmosphere to the earth’s surface
i.
Originate from a variety of air pollution sources and can be harmful to the
environment and public health
1. Acid deposition
2. Mercury
3. Microplastics
4. PFAS
5. Greenhouse gasses
Acid Deposition (Acid Rain): a mixture of wet and dry deposition from the
atmosphere containing higher than normal amounts of nitric and sulfuric acids
i.
Wet Deposition refers to pacific rain, fog, and snow
ii. Dry Deposition occurs when the environment is dry, arid chemicals are
incorporated into the dust or smoke sticking to surfaces of buildings,
ground, cars, and trees
1. Leads to acidic runoff
iii. Half of the acidity in the atmosphere falls back to earth through dry
deposition
iv.
the pH of acid rain is typically 5.6
v.
Effects
1. Surface water becomes more acidic
2. Damages forests at high elevations
3. Damages building materials
4. Affects human health
i. Nuclear Pollution: radioactive pollution
i.
Lead to radiation sickness and death
ii. Fallout can destroy environmental features and animal life
E. Climate Change Issues
a. Greenhouse Effect: warming that results when the atmosphere traps heat radiating
from Earth toward space
i.
Earth gets energy from the sun in the form of sunlight
ii. Earth’s surface absorbs some of this energy and heats up
iii. Earth cools down by giving off infrared radiation
iv.
Before radiation can escape, greenhouse gasses absorb some of it, making
the atmosphere warmer
v.
As the atmosphere gets warmer, Earth’s surface gets warmer
b. Earth’s temperature is dependent upon the greenhouse-like action of the
atmosphere, but the amount of heating and cooling is strongly influenced by
several factors
i.
Type of surface that sunlight first encounters
ii. Forests, grasslands, ocean surfaces, ice caps, deserts, and cities absorb,
reflect, and radiate radiation differently
iii. Sunlight falling on a white glacier surface strongly reflects it back into
space, resulting in minimal heating
iv.
Sunlight falling on dark desert soil is strongly absorbed, contributing to
significant heating of the surface and lower atmosphere
v.
Cloud cover can affect warming by reducing the amount of solar radiation
reaching the earth’s surface
vi.
Atmospheric gasses water vapor carbon dioxide, methane, and nitrous
oxide act as effective global insulators
vii.
Negative concerns related to possible impacts of an enhanced greenhouse
effect caused by excess pollutants going into the air
c. Ozone Depletion: ozone layer is deteriorating due to the release of pollution
containing the chemicals chlorine and bromine (chlorofluorocarbons or CFCs)
Part Three - Solutions for Reducing Harmful Effects