Transcript Ecosystems: What Are They and How Do They Work? APES Chapter 4

Ecosystems: What Are They and
How Do They Work?
APES Chapter 4
Chapter 4: Key Concepts
 Transfer of energy in ecosystems –
food
webs/ food chains/ ecological pyramids
 Biogeochemical cycles – carbon, nitrogen,
water, phosphorus, sulfur
 Soils – porosity, permeability, layers, age, location
 Layers of the Earth
 Topography
Biosphere
Ecosystem
Parts of the earth's air, water, and
soil where life is found
A community of different species
interacting with one another and with their
nonliving environment of matter and energy;
ABIOTIC with BIOTIC
Community
Populations of different species living in a
particular place, and potentially interacting
with each other
Population
A group of individuals of the same species
living in a particular place; specific
geographical area and interbreed.
Organism
An individual living being
Cell
Molecule
Atom
The fundamental structural and functional
unit of life
Chemical combination of two or more atoms
of the same or different elements
Smallest unit of a chemical element that
exhibits its chemical properties
Natural Capital:
General Structure
of the Earth
•The Earth is an integrated
system that consists of rock,
air, water, and living things
that all interact with each other.
•Scientists divided this system
into four parts:
1.
2.
3.
4.
Atmosphere
Hydrosphere
Geosphere
Biosphere
Fig 4.7
The Earth as a system – up close look
Geosphere- The Earth’s layers
These layers of material get
progressively denser as you
move toward the center of the
Earth.
Atmosphere
•The atmosphere is the
mixture of gases that
makes up the air we
breathe
•Mostly found in the first
30 km above the Earth’s
surface. (19 miles) TROPOSPHERE
Hydrosphere
The hydrosphere makes
up all of the water on or
near the Earth’s surface
Much of this water is in the
oceans, which cover
nearly ¾ of the globe.
However, water is also
found in the atmosphere,
on land, and in the soil.
Biosphere
The biosphere is the part
of the Earth where life
exists; a thin layer at the
Earth’s surface that
extends from about 9 km
(5.5 miles) above the
Earth’s surface down to
the bottom of the ocean.
The biosphere is therefore
made up of parts of the
lithosphere, the
atmosphere, and the
hydrosphere.
What Sustains Life on Earth?
 Solar energy
–one way
flow
 Cycling of
crucial
elements
 Gravity.
Flow of Energy to and from the Earth
Solar
energy
flowing through
the biosphere
warms the
atmosphere,
evaporates and
recycles water,
generates
winds and
supports plant
growth.
Greenhouse effect
 The greenhouse effect is the warming of the surface
and lower atmosphere of Earth that occurs when carbon
dioxide, water vapor, and other gases in the air absorb
and reradiated infrared radiation.
 Without the greenhouse effect, the Earth would be too
cold for life to exist.
 The gases in the atmosphere that trap and
radiate heat are called greenhouse gases.
 The most abundant greenhouse gases are
water vapor, carbon dioxide, methane, and
nitrous oxide, although none exist in high
concentrations.
How greenhouse gases lead to global warming: "An Inconvenient
Truth", Al Gore
4-3 What Are the Major Components
of an Ecosystem?
 Concept: Ecosystems contain living (biotic) and
nonliving (abiotic) components.
 Concept: Some organisms produce the
nutrients they need, others get their nutrients by
consuming other organisms, and some recycle
nutrients back to producers by decomposing the
wastes and remains of organisms.
Some ecosystems have very distinctive boundaries.
However, in most ecosystems it is difficult to determine
where one ecosystems stops and the next begins.
Ecosystem components
In order to survive, ecosystems need 5 basic
components:
1) energy
2) mineral nutrients
3) water
4) oxygen
5) living organisms
 The main source of energy for an ecosystem
comes from the SUN.
 If one part of the ecosystem is destroyed or
changes, the entire system will be affected.
Biomes
Biomes are based on climate
(average precipitation and temperature)
Several Abiotic Factors Can Limit
Population Growth
 Limiting factor principle
• Too much or too little of any abiotic factor can
limit or prevent growth of a population, even if
all other factors are at or near the optimal
range of tolerance.
Range of Tolerance for a Population
of Organisms
INSERT FIGURE 3-10 HERE
Limits to Population Growth
 Zone of toleranceHomeostasis
 Limiting factor examples
4-4 What Happens to Energy in an Ecosystem?
 Concept 4-4A Energy flows through
ecosystems in food chains and webs.
 Concept 4-4B As energy flows through
ecosystems in food chains and webs, the
amount of chemical energy available to
organisms at each succeeding feeding level
decreases.
Energy Flow through the Biophere
 Closed systems are systems that cannot
exchange matter or energy with its
surroundings.
 Open systems are systems that can exchange
both matter and energy with its surroundings.
 Today, the Earth is essentially a CLOSED
system with respect to matter, but an OPEN
system for energy as energy travels from plant
to animal which is eaten by other animals. In the
process, some energy is lost as heat to the
environment.
Energy Flow in Ecosystems- From Producers to
Consumers
 Some producers get their energy directly from
the sun by absorbing it and converting it to a
food source.
 Consumers get their energy indirectly by
eating producers or other consumers.
 Organisms break down carbohydrates and other
organic compounds in their cells to obtain the
energy they need, usually through aerobic
respiration.
Organisms can be classified by what they eat.
Types of Consumers:
•
•
•
•
Herbivores
Carnivores
Omnivores
Decomposers
 Each time an organism eats another organism,
an energy transfer occurs.
 This transfer of energy can be traced by
studying food chains, food webs, and trophic
levels.
A Food Chain
 A food chain is a
sequence in which
energy is transferred from
one organism to the next
as each organism eats
another organism.
 A food web shows many
feeding relationships that
are possible in an
ecosystem.
Detritivores and Decomposers on a Log
Trophic levels
 Each time energy is transferred, some of the
energy is lost as heat.
 Therefore, less energy is available to
organisms at higher trophic levels.
Pyramid of Energy Flow
Fig 3.15
Trophic Levels/ Biomass
More living organisms at the base of the pyramid = more biomass
Showing energy loss from 1
trophic level to the next- grass
stores 1,000 times more energy
than the hawk at the top level.
4-5 Primary Productivity of Ecosystems
 Gross primary
production
(GPP)
• Rate at which an
ecosystem’s
producers
convert solar
energy into
chemical energy
as biomass; the
rate is crucial
Net Primary Production (NPP)
NPP = GPP - respiration [by plants]
• Rate at which producers use
photosynthesis to store energy
minus the rate at which they use
some of this energy through
respiration (R).
 Net primary production takes into
account plant cellular respiration.
Estimated Annual Average NPP in Major
Life Zones and Ecosystems
BIODIVERSITY
 An important RENEWABLE resource
4 major kinds:
• Genetic biodiversity- a variety of genetic material within a
species or population
• Species Diversity- the variety among the species or
distinct types of living organisms found in different habitats
of the planet
• Ecological Diversity- the variety of different biomes
around the world; all biological communities
• Functional Diversity- biological and chemical processes
or functions such as energy flow and matter cycling
needed for the survival of species and biological
communities
BIODIVERSITY

Origins- parent material; mixtures of
eroded rock, mineral nutrients,
decaying organic matter, and billons
of living organisms (mostly
decomposers)
 Soil Horizons based on the type
of material the horizons are
composed of; these materials
reflect the duration of the specific
processes used in soil formation.
They are described and classified
by their color, size, texture,
structure, consistency, root
quantity, pH, voids, boundary
characteristics, or concretions.
-
O horizon = leaf litter,
crop/animal waste; organic
materials
-
A horizon = topsoil; humus
(decomposed organic matter
with inorganic minerals);
darker = more nutrients
-
B horizon = subsoil; mostly
inorganic, made of broken
down rock; reddish color due
to iron oxides and clay
-
C horizon = unweathered
parent rock, bedrock
4-6
SOILS
Soil horizon
development
animation
Variations with Climate and Biomes
 Soil formation greatly depends on the climate, and soils from
different biomes show distinctive characteristics.
 Temperature and moisture affect weathering and leaching. Wind
moves sand and other particles, especially in arid regions where
there is little plant cover. The type and amount of precipitation
influence soil formation by affecting the movement of ions and
particles through the soil, aiding in the development of different soil
profiles.
Soil Profiles in Different
Biomes
Mosaic
of closely
packed
pebbles,
boulders
Weak humusmineral mixture
Alkaline,
dark,
and rich
in humus
Dry, brown to
reddish-brown, with
variable accumulations
of clay, calcium
carbonate, and
soluble salts
Desert Soil
(hot, dry climate)
Clay,
calcium
compounds
Grassland Soil
(semiarid climate)
Forest litter
Leaf and
mold
Acidic
lightcolored
humus
Humus-mineral
mixture
Light, grayishbrown, silt loam
Iron and
aluminum
compounds
mixed with
clay
Tropical Rain Forest Soil
(humid, tropical climate)
Dark brown
firm clay
Deciduous Forest Soil
(humid, mild climate)
Acidic litter
and humus
Light
colored and
acidic
Humus with
iron and
aluminum
compounds
Coniferous Forest Soil
(humid, cold climate)
Soil porosity and permeability



Soil porosity refers to that part of a soil volume that is not occupied by soil
particles or organic matter. Pore spaces are filled with either air, other
gases, or water. Large pores (macropores) allow the ready movement of air
and the drainage of water.
Soil permeability- rate at which water and air move from upper to lower
layers
LOAM= between silt and clay (inorganic); crumbly, spongy texture;
excellent for plant growth
Permeability ANIMATION
 Soil types
Nutrients Cycle in the Biosphere
 Biogeochemical cycles, nutrient cycles
•
•
•
•
•
Hydrologic
Carbon
Nitrogen
Phosphorus
Sulfur
HYDROLOGIC CYCLE
 Natural renewal of water quality: 3 major
processes
• Evaporation
• Precipitation
• Transpiration
 Alteration of the hydrologic cycle by humans
• Withdrawal of large amounts of freshwater at
rates faster than nature can replace it
• Clearing vegetation leads to increased runoff
• Increased flooding when wetlands are drained
Hydrologic Cycle Including Harmful
Impacts of Human Activities
Carbon Cycle
 Depends on Photosynthesis and Respiration
 Link between photosynthesis in producers and
respiration in producers, consumers, and
decomposers
 Alteration of the carbon cycle by humans
Additional CO2 added to the atmosphere
• Tree clearing
• Burning of fossil fuels- energy and transportation
Natural Capital: Carbon Cycle with Major
Harmful Impacts of Human Activities
The Carbon Cycle
Nitrogen Cycle
 Bacteria in action
 Alteration of the nitrogen cycle by humans
Additional NO and N2O
•
•
•
•
Burning fuels
Destruction of forest, grasslands, and wetlands
Add excess nitrates to bodies of water
Remove nitrogen from topsoil
The Nitrogen Cycle
Nitrogen Cycle in a Terrestrial Ecosystem
with Major Harmful Human Impacts
Annual Increase in Atmospheric N2 Due
to Human Activities
Phosphorus Cycle
 Cycles through water, the earth’s crust, and
living organisms
 May be limiting factor for plant growth
 Alteration of the phosphorous cycle by
humans
• Clearing forests
• Mining and human wastes
• Removing large amounts of phosphate from the
earth to make fertilizers
The Phosphorus Cycle
Phosphorus Cycle with Major Harmful
Human Impacts
Fig 3.21
Sulfur Cycle
 Sulfur found in organisms, ocean sediments,
soil, rocks, and fossil fuels
 SO2 in the atmosphere
 DMS (Dimethyl Sulfide)- produced by marine
algae
 Sulfuric acid = acid rain; H2SO4 and SO4Alteration of the sulfur cycle by humans
Burn sulfur-containing coal and oil
• Refine sulfur-containing petroleum
• Convert sulfur-containing metallic mineral ores
Natural Capital: Sulfur Cycle with Major
Harmful Impacts of Human Activities
Fig 3.21
4-8 How Do Ecologists Learn About Ecosystems?
 Field Research- observing/measuring ecosystem structure and
function
 Remote sensing and Geographic information systems (GIS)new technologies that gather data fed through a computer for
analysis. (ie. Computer generated maps of forest cover, coastal
changes,etc)
 Laboratory Research- controlled chambers such as tanks,
greenhouse; control CO2, temperature, light, humidity
 Mathematical models- simulations of ecosystems that are large,
complex, or difficult to study in the field/lab (ocean floor)
Geographic Information Systems (GIS)
 A GIS organizes,
stores, and analyzes
complex data
collected over broad
geographic areas.
 Allows the
simultaneous overlay
of many layers of
data.