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Succession
I. Successional Changes in Communities
A. Succession
1. The gradual, sequential growth of species in an area
2. Pioneer species
a. Species that predominate early succession
b. Small, fast growing, and fast reproducing
1. Lichens, annual grasses/flowers, perennial grasses/flowers
B. Primary succession
1. Development of a community in an area that has NEVER supported life
previously
a. Very, very slow (about 200 years)
b. No soil or nutrients have formed yet
c. Lichens annual grasses perennial grasses shrubstrees
C. Secondary Succession
1. Development of a community in an area where an EXISTING
community has been cleared by a disturbance
a. Forest fire, drought, farming, hurricane, etc
b. Much faster than primary succession
c. Soil has been left intact
d. Annual grasses perennial grasses shrubs trees
Chapter 37 Community Ecology
I. Competition
A. −/−
B. Ecological niche
1. Sum of an organisms use of the abiotic and biotic resources in its env.
C. When would this occur, what would cause
1. When ecological niches of 2 populations overlap & resources limited
Organisms within a community will have to compete for resources
a. Remember, one of the driving forces behind evolution
D. Lowers carrying capacity of populations
II. Mutualism
A. +/+
B. Corals-Dinoflagellates/Lichen
III. Predation
A. +/B. Predators, prey, and natural selection
1. Predators
a. Survival depends on ability to capture food
b. Natural selection favors traits that make predators efficient at
capturing prey
2.
2. Prey
A. Natural selection favors traits that make prey efficient at avoiding
being captured
C. Mimicry
1. One organism copying another organism
D. Plant-Herbivore interactions
1. +/2. Physical and/or chemical defenses
a. Thorns, poison ivy
Trophic Levels/Food chains/Food webs
I. Producers
A. Intro
1. All organisms need food to survive
a. Growth, movement, maintenance & repair, etc.
2. What is the ultimate source of energy in an ecosystem?
a. The sun’s energy enters into an ecosystem through what
organism?
b. Plants convert the sun’s energy into what form of energy?
3. Producers
a. Autotrophs
1. Any organism within an ecosystem that captures energy to make
organic molecules
a. Can manufacture their own food
b. Examples
1. Terrestrial ecosystem=Plants
B. Measuring productivity
1. The amount of energy captured by producers and available to all
nonproducers in an ecosystem
a. Will all the energy captured by producers be available no
producers
1. Why?
b. Biomass
1. All organic material within an ecosystem
2. The amount of biomass in an ecosystem is directly related to
productivity
3. What type of ecosystem/Biome would have the highest productivity?
II. Consumers
A. Heterotrophs
1. Organisms within an ecosystem that obtain organic food molecules by
eating other organisms or their waste
a. Cannot manufacture their own food
2. 4 categories
a. Herbivores
b. Carnivores
c. Omnivores
1. Eat both producers and consumers
2. Examples?
d. Detrivores
1. Consumers that eat the “garbage” of an ecosystem
a. Dead organisms (plants,animals,etc) and their waste
2. Scavengers and decomposers
III. Energy flow
A. Intro
1. Once energy enters an ecosystem it must flow through the
ecosystem in order for all organisms to obtain energy
2. Trophic levels
a. Shows the feeding relationship among organisms consisting of
several different levels
b. The position of an organism in the sequence of food consumption
c. Producers belong at the 1st trophic level (bottom)
1. Largest group
B. Food chains and food webs
1. Food chains
a. Shows the feeding relationship among organisms consisting of
several different levels
1. Starts with producers
b. A single linear transfer
2. Food webs
a. Shows the relationship between food chains within an ecosystem
C. Quantity of energy transfers
1. Remember, we cannot transfer 100% of energy(food)
a. Some energy will always be lost as what?
b. 10% rule
b. Some of the energy gets used by the organism itself
1. This energy is not available to the next consumer (trophic
level)
c. Some organisms do not get eaten
II. The Carbon Cycle
A. Carbon is the building block for all organic compounds
B. Movement/recycling of carbon throughout an ecosystem
1. Major source of carbon in an ecosystem is CO2
C. 2 important processes in the carbon cycle
1. Photosynthesis
a. Takes CO2 out of the atmosphere to make carbohydrates
2. Cellular respiration
a. Returns CO2 into the atmosphere by breaking down carbohydrates
III. Nitrogen cycle
A. Nitrogen is essential building block for all proteins
B. Movement/recycling of nitrogen throughout an ecosystem
C. 2 important processes in the nitrogen cycle
1. Nitrogen fixation
a. Most nitrogen in an ecosystem not in a usable form
1. A gas in the atmosphere
b. Nitrogen-fixing bacteria are the only organisms that can transform
nitrogen gas in the atmospohereinto usable nitrogen
1. Release excess nitrogen into soil allowing plants to take up
by
2. Denitrification
a. Process of returning
nitrogen back to the
atmosphere as a gas
b. Bacteria change usable
nitrogen back into nitrogen gas
decomposing dead
organisms