Transcript Terrestrial Ecology Unit overview

Terrestrial Ecology
Unit overview
What is ecology?
What basic processes keep us and other organisms alive?
What are the major components of an ecosystem?
What happens to energy in an ecosystem?
What are soils and how are they formed?
What happens to matter in an ecosystem?
How do scientists study ecosystems?
What factors the earth’s climate?
How does climate determine where the earth’s major
biome’s are found?
What are the major types of desert biomes?
What are the major types of grassland biomes?
What are the major types of forest and mountain biomes?
How have human activities affected the world’s desert,
grassland, forest, and mountain biomes?
Ecology….
-is a study of
connections in
nature.
-is how organisms
interact with one
another and with
their nonliving
environment.
ORGANISM: one of the many different
forms of life on earth. They are
classified into different species based
on certain characteristics.
POPULATION: A group of individual
organisms of the same species living
w/in a particular area.
COMMUNITY: The population of all
species living & interacting in an area.
ECOSYSTEM: A community of different
species interacting together & with the
chemical & physical factors making up
its non-living environment.
• Ecosystems consist of nonliving (abiotic) and
living (biotic) components.
Habitat and Niche
Habitat:
the place in which an
organism or population
lives.
Niche:
All of the physical,
chemical, and
biological conditions
a species needs to
live & reproduce in
an ecosystem.
• Biological communities differ in the types and
numbers of species they contain and the
ecological roles those species play.
– Species diversity: the number of different species
it contains (species richness) combined with the
abundance of individuals within each of those
species (species evenness).
(No, I’m not going to make you do this!)
Keystone species
Keystone species are species that enrich ecosystem
function in a unique and significant manner through
their activities, and the effect is disproportionate to
their numerical abundance. Their removal initiates
changes in ecosystem structure and often loss of
diversity.
Indicator species
• Species that serve as early warnings of
damage to a community or an ecosystem.
– Example: Presence or absence of trout species
because they are sensitive to temperature and
oxygen levels.
Case Study:
Why are Amphibians Vanishing?
• Frogs serve as an indicator species because
different parts of their life cycles can be easily
disturbed.
Case Study:
Why are Amphibians Vanishing?
•
•
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•
•
•
•
•
Habitat loss and fragmentation.
Prolonged drought.
Pollution.
Increases in ultraviolet radiation.
Parasites.
Viral and Fungal diseases.
Overhunting.
Natural immigration or deliberate introduction of
nonnative predators and competitors.
SPECIES INTERACTIONS:
• Species can interact through
competition, predation, parasitism,
mutualism, and commensalism.
• Some species evolve adaptations that
allow them to reduce or avoid
competition for resources with other
species.
Predation
Predator:
An organisms that
captures & feeds on
parts or all of another
animal.
Prey:
An organisms that is
captured & serves as a
source of food for another
animal.
Competition
When two or more individuals rely on the
same limited resource.
Parasitism:
• Although parasites can harm their hosts, they
can promote community biodiversity.
– Some parasites live in host (micororganisms,
tapeworms).
– Some parasites live outside host (fleas, ticks,
mistletoe plants, sea lampreys)
Mutualism:
• Two species
can interact in
ways that
benefit both of
them.
Figure 7-9
Commensalism:
• Some species
interact in a
way that helps
one species but
has little or no
effect on the
other.
Figure 7-10
Producers
• Most producers (autotrophs) capture sunlight
to produce carbohydrates by photosynthesis:
 Photosynthesis:
The process in which glucose is
synthesized by plants.
Productivity
• The amount of increase in organic
matter per unit of time.
Abundance of organisms
Upper limit of
tolerance
Few
No
organisms organisms
Population size
Lower limit of
tolerance
No
Few
organisms
organisms
Zone of
intolerance
Low
Zone of
physiological
stress
Optimum range
Temperature
Zone of
physiological
stress
Zone of
intolerance
High
Fig. 3-11, p. 58
Consumers
• Consumers
(heterotrophs) get
their food by
eating or breaking
down all or parts
of other
organisms or their
remains.
– Herbivores
• Primary consumers
that eat producers
– Carnivores
• Secondary consumers
eat primary consumers
• Tertiary & Quaternary
consumers: carnivores
that eat carnivores.
– Omnivores
• Feed on both plant and
animals.
Decomposers and Detritivores
– Decomposers: Recycle nutrients in ecosystems.
– Detritivores: Insects or other scavengers that feed on
wastes or dead bodies.
Figure 3-13
First Trophic
Level
Second Trophic
Level
Third Trophic
Level
Producers
(plants)
Primary
consumers
(herbivores)
Secondary
consumers
(carnivores)
Heat
Heat
Fourth Trophic
Level
Tertiary
consumers
(top carnivores)
Heat
Solar
energy
Heat Heat
Heat
Heat
Heat
Detritivores
(decomposers and detritus feeders)
Fig. 3-17, p. 64
Food Webs/Chains
• Determines how energy & nutrients move from one
organism to another through an ecosystem.
• Below: the decrease in energy available at each
succeeding trophic level in a food chain or web.
Energy Flow in an Ecosystem:
Losing Energy in Food Chains and Webs
• In accordance with the 2nd law of
thermodynamics, there is a decrease in the
amount of energy available to each succeeding
organism in a food chain or web. (Entropy)
Note:
The 1st Law of Thermodynamics states that “energy can be changed from one form
to another, but it cannot be created or destroyed”.
The 2nd Law of thermodynamics states that "in all energy exchanges, if no energy
enters or leaves the system, the potential energy of the state will always be less
than that of the initial state."
First Trophic
Level
Second Trophic
Level
Third Trophic
Level
Producers
(plants)
Primary
consumers
(herbivores)
Secondary
consumers
(carnivores)
Heat
Heat
Fourth Trophic
Level
Tertiary
consumers
(top carnivores)
Heat
Solar
energy
Heat Heat
Heat
Heat
Heat
Detritivores
(decomposers and detritus feeders)
Fig. 3-17, p. 64
The 10% Rule
• We assume that 90% of the energy at each
energy level is lost because the organism
uses the energy.
• It is more efficient to eat lower on the
energy pyramid.
• This is why top predators are fewer in
number & vulnerable to extinction.
Biomass
• The organic matter
produced by plants; dry
weight. Energy from
wood, garbage &
agricultural waste. Can
be used for electrical
energy production
(burning).
Tragedy of the Commons
• A common-property resource, which are
owned by no one but are available to all users
free of charge.
• Most are potentially renewable.
• Ex. Clean air, open ocean
and its fish, migratory
birds, Antarctica, the
ozone, and space.
Habitat Needs
• Cover, Water, & Nutrients
• Macronutrients:
Chemicals organisms need
in large numbers to live,
grow, and reproduce.
(C, H, O, N, Ca, Fe)
• Micronutrients:
These are needed in small
or even trace amounts.
(Na, Zi, Cu, Cl)
Nutrient Cycles
Biosphere
Carbon
cycle
Phosphorus
cycle
Nitrogen
cycle
Water
cycle
Oxygen
cycle
Heat in the environment
Heat
Heat
Heat
Fig. 3-7, p. 55
Effects of Human Activities
on Carbon Cycle
• We alter the carbon
cycle by adding
excess CO2 to the
atmosphere
through:
– Burning fossil fuels.
– Clearing vegetation
faster than it is
replaced.
Figure 3-28
Phosphorous
Cycle
Effects of Human Activities
on the Phosphorous Cycle
• We remove large amounts of phosphate
from the earth to make fertilizer.
• We reduce phosphorous in tropical soils by
clearing forests.
• We add excess phosphates to aquatic
systems from runoff of animal wastes and
fertilizers.
Phosphorus
• Bacteria are not as important in the phosphorus cycle
as in the nitrogen cycle.
• Phosphorus is not usually found in the atmosphere or
in a gas state only as dust.
• The phosphorus cycle is slow and phosphorus is
usually found in rock formations and ocean sediments.
• Phosphorus is found in fertilizers because most soil is
deficient in it and plants need it.
• Phosphorus is usually insoluble in water and is not
found in most aquatic environments.
Nitrogen
Cycle
Effects of Human Activities
on the Nitrogen Cycle
• We alter the nitrogen cycle by:
– Adding gases that contribute to acid rain.
– Adding nitrous oxide to the atmosphere through
farming practices which can warm the atmosphere
and deplete ozone.
– Contaminating ground water from nitrate ions in
inorganic fertilizers.
– Releasing nitrogen into the troposphere through
deforestation.
Effects of Human Activities
on the Nitrogen Cycle
• Human activities
such as
production of
fertilizers now
fix more
nitrogen than all
natural sources
combined.
Figure 3-30
Processes in the Nitrogen Cycle:
1. Nitrogen Fixation: specialized bacteria convert gaseous
nitrogen to ammonia that can be used by plants.
2. Nitrification: Ammonia is converted to nitrite, then to nitrate.
3. Assimilation: Plant roots absorb ammonium ions and nitrate
ions for use in making molecules such as DNA, amino acids and
proteins.
4. Ammonification: After nitrogen has served its purpose in
living organisms, decomposing bacteria convert the nitrogenrich compounds, wastes, and dead bodies into simpler
compounds such as ammonia.
5. Denitrification: Nitrate ions and nitrite ions are converted into
nitrous oxide gas and nitrogen gas. This happens when a soil
nutrient is reduced and released into the atmosphere as a gas.
CLIMATE: A BRIEF INTRODUCTION
• Weather is a local area’s short-term physical
conditions such as temperature and
precipitation.
• Climate is a region’s average weather conditions
over a long time.
– Latitude and elevation help determine climate.
BIOMES
• Biomes – large terrestrial regions characterized by similar
climate, soil, plants, and animals.
• The most important factors in a biome are temperature and
precipitation.
• Biomes tend to converge around latitude lines on the globe.
• Different climates lead to different communities of
organisms, especially vegetation.
• Each biome contain many ecosystems whose communities.
have adapted to differences in climate, soil, etc.
BIOMES:
Figure 5-9
HUMAN IMPACTS ON TERRESTRIAL
BIOMES
• Human activities have damaged or disturbed
more than half of the world’s terrestrial
ecosystems.
• Humans have had a number of specific harmful
effects on the world’s deserts, grasslands,
forests, and mountains. The following slides
show some of the impacts.
Natural Capital Degradation
Desert
Large desert cities
Soil destruction by off-road
vehicles
Soil salinization from
irrigation
Depletion of groundwater
Land disturbance and
pollution from mineral
extraction
Fig. 5-26, p. 123
Natural Capital Degradation
Grasslands
Conversion to cropland
Release of CO2 to atmosphere
from grassland burning
Overgrazing by livestock
Oil production and off-road
vehicles in arctic tundra
Fig. 5-27, p. 123
Natural Capital Degradation
Forests
Clearing for agriculture, livestock
grazing, timber, and urban
development
Conversion of diverse forests to tree
plantations
Damage from off-road vehicles
Pollution of forest streams
Fig. 5-28, p. 124
Natural Capital Degradation
Mountains
Agriculture
Timber extraction
Mineral extraction
Hydroelectric dams and
reservoirs
Increasing tourism
Urban air pollution
Increased ultraviolet radiation
from ozone depletion
Soil damage from off-road
vehicles
Fig. 5-29, p. 124
Reclamation
• Returning vegetation to an area that has been
mined or disturbed by human use.
• This can be done by re-planting, cleaning up
pollution, regulations (laws) or any other
activity designed to “fix” a destroyed area.
• Reclaiming an area will promote habitat
restoration.
Ecological Succession
• The process where plants & animals of
a particular area are replaced by other
more complex species over time.
Primary & Secondary Succession
• Primary succession begins with a lifeless area
where there is no soil (ex. bare rock). Soil
formation begins with lichens or moss.
• Secondary succession begins in an area where
the natural community has been disturbed,
removed, or destroyed, but soil or bottom
sediments remain.
Pioneer Communities
• The species that find habitat
at the beginning of
succession.
• In primary succession, the
common species are mosses
and lichen. (*lichen are a
symbiotic relationship
between bacteria and fungi)
Moss (on a rock!)
Lichen (on a tree!)
Climax Community
• A final stable community of organisms (the end
of succession)
• Areas dominated by a few, long-lived plant
species.