Transcript Phosphorus and Nitrogen Cycles

Ecosystems &
Biological
Communities
Interactions
Ecology is the study
of the interactions of
living organisms with
one another.
What does the word
really mean?
house or place where
one lives
The place where
an organism lives
is its habitat.
A community is
made up of many
different species
that live
together.
Interaction in an Ecosystem
Define biotic factors: organisms in a habitat
Fish in water
Rabbit in a burrow
Squirrel in a tree
Interaction in an Ecosystem
Define abiotic
factors:
physical
aspects of a
habitat
Soil
Sand
Water
Energy Flow in Ecosystems
Most life on earth
depends on
photosynthetic
organisms which
capture some of the
sun’s light energy and
store it as chemical
energy in organic
molecules.
What is the equation for
photosynthesis?
6 CO2 + 6 H2O
+ light  C6H12O6 + 6 O2
Organisms that are the first to capture
energy are the producers which
include plants, some kinds of
bacteria, and algae.
Consumers are those organisms that
consume plants or other organisms to
obtain the energy to build their
molecules.
Trophic Levels
Food Chains
What occupies the first or lowest trophic level of any
ecosystem?
Producers
What occupies the 2nd trophic level?
Herbivores (primary consumers)
What occupies the 3rd trophic level?
Secondary consumers
What is the difference between a
carnivore and an omnivore?
Carnivores eat meat only, Omnivores
eat meat and plants
Many ecosystems contain a 4th trophic
level composed of carnivores that
consume other carnivores.
Do ecosystems usually have more
than 4 trophic levels?
Rarely
What role do bacteria and fungi play
in an ecosystem?
Decomposers (break down dead
plant and animal matter)
Loss of Energy in Food Chain
During every transfer of energy within an
ecosystem, energy is lost as heat.
The loss of useful energy limits the number of
trophic levels an ecosystem can support. At
each trophic level, the energy stored by the
organisms in a level is about 1/10 of that
stored by the organisms in the level below.
Ecologists often illustrate that flow of energy
through ecosystems with an energy pyramid.
Energy Pyramid: a diagram in which each trophic
level is represented by a block and the blocks are
stacked on top of one another.
How many trophic levels are in Figure 9?
4
Why is the top trophic level the smallest?
Least amount of energy
Practice
If the first trophic level contained 10,000
kcal of energy, how much energy would
the 2nd level have? 1,000 kcal
3rd? 100 kcal
4th? 10 kcal
Cycling of Materials in
Ecosystems
All materials that cycle through living
organisms are important in
maintaining the health of ecosystems,
but 4 substances are particularly
important: water, carbon, nitrogen
and phosphorus.
Cycles
The paths of water, carbon, nitrogen
and phosphorous pass from the
nonliving environment to living
organisms, such as trees and then
back to the nonliving environment.
The Water Cycle
Water has the greatest influence on the
ecosystem’s inhabitants.
Water vapor in the atmosphere
condenses and falls to the Earth’s
surface as rain or snow. The water
that seeps into the soil becomes part
of the ground water.
Water Cycle
Water is taken up by the roots
of plants and then moves into the
atmosphere by evaporating from the leaves
through transpiration.
Water Cycle
The Carbon Cycle
Carbon dioxide in the air or dissolved
in water is used by
photosynthesizing plants, algae and
bacteria as a raw material to build
organic molecules. Carbon atoms
may return to the pool of carbon
dioxide in the air and water in 3
ways.
The Carbon Cycle
1. Respiration- all
organisms use
oxygen to oxidize
organic molecules
producing carbon
dioxide.
The Carbon Cycle
2. Combustion- The
burning of wood
returns carbon to
the atmosphere, as
well as coal, oil,
and natural gas.
The carbon is
released when the
fossil fuel is burned.
Smoke and pollution from
Borneo fires, 1997.
The Carbon Cycle
3. Erosion-As limestone is exposed
and erodes, the carbon becomes
available to other organisms.
Also includes decomposition
The Carbon Cycle
The Phosphorus and Nitrogen
Cycles
Organisms need nitrogen
and phosphorus to build
proteins and nucleic
acids. Phosphorus is an
essential part of both ATP
and DNA.
Phosphorus and Nitrogen Cycles
Phosphate is absorbed by
the roots of plants and is
eaten by animals.
The atmosphere is 79%
nitrogen gas, N2 but it is
in an unusable form.
Phosphorus and Nitrogen Cycles
Some bacteria can break the
bond between the nitrogen
molecules to form ammonia
(NH3). This is called nitrogen
fixation. These bacteria live
in the soil and are also found
in the nodules of roots of
beans, alder trees and a few
other kinds of plants.
The Phosphorus
4 stages of the Nitrogen Cycle:
1. Assimilation- absorption and
incorporation of nitrogen into
plant and animal compounds
2. Ammonification- production of
ammonia by bacteria during the
decay of nitrogen- containing
urea (found in urine).
4 stages of the Nitrogen Cycle:
3. Nitrification- production of
nitrate from ammonia
4. Denitrification- the conversion
of nitrate to nitrogen gas.
The Nitrogen Cycle
Nitrogen Cycle
Plant growth is limited by the availability of
nitrate and ammonia in the soil. Most
farmers add nitrates to the soil that
has been made in a factory rather than
by nitrogen fixation. Genetic engineers
are trying to put the genes of the nitrogenfixing bacteria into plants. This would
eliminate the need for nitrogen-supplying
fertilizers.
Biological Communities
What is predation?
The act of one organism killing another organism
for food
List 2 examples of predation.
1. bear and a fish
2. lions and gazelle
Symbiotic Species pg. 364
Define:
symbiosis: two or more species live
together in a close, long-term association
Symbiotic relationships can be beneficial to
both organisms or benefit one and leave
the other harmed or unaffected.
Parasitism
Parasitism is when one organism feeds on
and usually lives on or in another
organism. Parasites do not usually kill
their “host”.
Example- fleas/ticks on dogs
Mutualism
Mutualism is when both organisms benefit.
Examples: plover and Rhino
Commensalism
Commensalism is when one
organism benefits and the
other is neither harmed or
helped.
Examples: clown fish and sea anemone
Define:
competition: two species use the same
resource; they participate in a biological
interaction
What resources might species compete for?
Water, food, nesting site, living space, light,
mineral nutrients
Do most interactions involve fighting?
no
Define:
niche: functional role of a particular
species in an ecosystem
In what ways can a niche be described?
How an organism lives OR the “job” it
performs within the ecosystem
Climate’s Effect on Where
Species Live
A. The 2 most important element of
climate are temperature and
moisture.
B. A major biological community that
occurs over a large area of land is
called a biome.
7 Most Widely Recognized Land
Biomes Are:
1. Tropical Rainforest
2. Savanna
3. Taiga
4. Tundra
5. Desert
6. Temperate Grassland
7. Temperate Forest
1.
Deciduous
2.
Evergreen
Many factors such as soil type and wind
play an important role in determining where
biomes occur.
Aransas
National
Wildlife
Refuge
Austwell,
TX
Tropical Rainforest
• Average 180 in.
rainfall annually
• More species
than other biomes
• ≥ half of
terrestrial species
• Infertile soil
(nutrients stored in
plants
Dominica, West Indies
Savanna
• Dry grassland
with prolonged dry
season
• 35-60 in. rainfall
• Widely spaced
trees
• Supports huge
herds of grazers
Africa
Taiga
• Cold, wet climate
with long winters
• Coniferous trees
• Largest biome
• Home of elk, moose,
deer, wolves, bears,
lynxes, wolverines
Tundra
Found between taiga
and permanent ice
around North pole
Covers 1/5 of land
surface
< 25 in. rainfall
Permafrost- ground
frozen within 3 ft. of
surface
Desert
• < 10 in. rainfall
(varies greatly in
specific locations)
• Sparse vegetation
• < 5% of North
America
• Usually in interior
of continent
Langtry, TX near
Rio Grande River
Temperate Grassland
• Moderate climate
halfway between poles
and equator
• Deep, fertile soils
• Maintained by herds
of migratory grazers or
fire
Cara and Rosie
Temperate Deciduous Forest
Trees shed leaves in
fall
Warm summers, cold
winters
Rainfall = 30-100 in.
Eastern U.S.
Deer, bears, beaver,
raccoon,
Hardwood trees
Temperate Evergreen Forest
Drier weather than
deciduous, acidic soil
SE & W U.S.
Pine needles have
resin to prevent water
loss
Seeds protected in pine
cone
Ca. Redwood- tallest
tree in world (up to 378
ft) and lives 2,000 years
Aquatic Communities
Freshwater Communities- include lakes,
ponds, streams, and rivers.
3 zones that ponds and lakes have
include:
1. Littoral- shallow end near the shore
2. Limnetic- farther from shore but
close to surface
3. Profundal- deep water zone that is
below where light penetrates
Wetlands
Wetlands include
swamps, marshes,
and bogs.
Wetlands are dynamic communities
that support a diverse array of
invertebrates, birds, and other
animals.
Marine Communities
Nearly ¾ (75%) of the Earth’s surface is
covered by ocean.
3 types of Marine communities:
1. Shallow ocean waters
What is the intertidal zone?
Seashore between high and low
tides; home of many invertebrates
2. Surface of the open seas
What is plankton? Bacteria, algae,
fish larvae, small invertebrates
3. Ocean Depths- deepest water of
the sea