Ecosystems

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• Ecosystems Biological Communities

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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

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The place where an organism lives is its habitat.

• A community is made up of many different species
  that live together.

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Interaction in an Ecosystem

• Define biotic factors organisms in a habitat

Fish in water
Rabbit in a burrow
Squirrel in a tree
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Interaction in an Ecosystem

• Define abiotic factors physical aspects of a
  habitat

Soil
Sand
Water
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Energy Flow in Ecosystems

• Most life on earth depends on photosynthetic
  organisms which capture some of the suns light
  energy and store it as chemical energy in organic
  molecules.

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• What is the equation for
• photosynthesis?
• 6 CO2 6 H2O light ? C6H12O6 6 O2

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• 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.

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Trophic Levels
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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

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• 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.

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• 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)

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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.

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Energy Pyramid a diagram in which each trophic
level is represented by a block and the blocks
are stacked on top of one another.
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How many trophic levels are in Figure 9? Why is
the top trophic level the smallest?
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Least amount of energy
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Practice

• If the first trophic level contained 10,000 kcal
  of energy, how much energy would the 2nd level
  have?
• 3rd?
• 4th?

1,000 kcal
100 kcal
10 kcal
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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.
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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.
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The Water Cycle
Water has the greatest influence on the
ecosystems inhabitants. Water vapor in the
atmosphere condenses and falls to the Earths
surface as rain or snow. The water that seeps
into the soil becomes part of the ground water.
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Water Cycle
Water is taken up by the roots of plants
and then moves into the atmosphere by evaporating
from the leaves through transpiration.
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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.
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The Carbon Cycle
1. Respiration- all organisms use oxygen to
oxidize organic molecules producing carbon
dioxide.
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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.
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The Carbon Cycle
3. Erosion-As limestone is exposed and erodes,
the carbon becomes available to other
organisms. Also includes decomposition
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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.
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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.
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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.
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The Phosphorus
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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).
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4 stages of the Nitrogen Cycle
3. Nitrification- production of nitrate from
ammonia 4. Denitrification- the conversion of
nitrate to nitrogen gas.
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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 nitrogen-fixing bacteria into plants. This
would eliminate the need for nitrogen-supplying
fertilizers.
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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

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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.

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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

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Mutualism

• Mutualism is when both organisms benefit.
• Examples plover and Rhino

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Commensalism

• Commensalism is when one
• organism benefits and the
• other is neither harmed or
• helped.
• Examples clown fish and sea anemone

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• 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

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• 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

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Climates 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.
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7 Most Widely Recognized Land Biomes Are

• 1. Tropical Rainforest
• 2. Savanna
• 3. Taiga
• 4. Tundra
• 5. Desert
• 6. Temperate Grassland
• Temperate Forest
• Deciduous
• Evergreen

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• Many factors such as soil type and wind play an
  important role in determining where biomes occur.

Aransas National Wildlife Refuge Austwell, TX
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Tropical Rainforest

• 78-177 inches of rainfall annually
• 68F 86F average 77F
• More species than other biomes, richest most
  abundant, ½ of terrestrial species
• Winter/Summer little to no difference in
  temperature

Dominica, West Indies
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Savanna

• 35-60 in. rainfall
• 59F 86F Temperature
• Winter/Summer more fluctuation than Rain
  Forest but still very little change
• Widely spaced trees and grasses
• Supports huge herds of grazing animals

Africa
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Taiga

• Rainfall 13 29 inches
• Temperature 50F 57F
• Cold, wet climate with long winters Summers is
  when most precipitation falls
• Coniferous trees (spruce fir)
• Home of elk, moose, deer, wolves, bears, lynxes,
  wolverines
• Largest biome

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Tundra

• Found between taiga and permanent ice around
  North pole, Covers 1/5 of land surface
• Permafrost- ground frozen within 3 ft. of surface
• lt 10 in. rainfall
• Temperature 35.6F - 59F
• Winter Long cold 10 months
• Summers short and cool only last 2 months
• Grasses and Mosses
• Foxes, lemmings, owls, caribou

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Desert

• lt 10 in. rainfall (varies greatly in specific
  locations)
• Temperature 44.6F 100.4F
• Winters are cold Summers are extremely hot
• Sparse vegetation cactus
• Kit foxes, lizards, snakes
• lt 5 of North America
• Usually in interior of continent

Langtry, TX near Rio Grande River
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Temperate Grassland

• Moderate climate halfway between poles and
  equator, deep, fertile soils
• Rainfall 9-29 inches
• Temperature 32F-77F
• Winters cold
• Summers Warm to hot
• Grasses way to dry for trees
• Maintained by herds of migratory grazers
  (bison, cows, buffalo) or fire

Cara and Rosie
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Temperate Deciduous Forest

• Trees shed leaves in
  
  fall,
  Eastern U.S.
• Rainfall 30-100 in.
• Temperature 42.8F 82.4F
• Warm summers, cold winters
• Hardwood trees oaks, hickory, beech
• Deer, beaver, raccoon

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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
• Rainfall 29-98 inches
• Temperature 42.8F - 82.4F
• Winter Very Stormy, snow, hail
• Summer Hot
• Evergreen trees pine trees, dry shrubs,
  California Redwood- tallest tree in world and
  lives 2,000 years
• Animal Life birds, snakes, owls, bears, deer

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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

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Wetlands

• Wetlands include
• swamps, marshes,
• and bogs.
• Wetlands are dynamic communities that support a
  diverse array of invertebrates, birds, and other
  animals.

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Marine Communities

• Nearly ¾ (75) of the Earths surface is covered
  by ocean.

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• 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