Download Chapter 17 Notes - Net Start Class

Chapter 17 Notes
Section 17-1 “What is an Ecosystem?”
Ecosystem: all of the living and nonliving things that interact in a particular area.
The organisms in an ecosystem are Biotic Factors (birds, mouse, grass)
Non-living things are called abiotic factors. (sunshine, water, oxygen, air
temperature)
Habitat and Niche
Every organism requires food, water, and living space.
Habitat: place in the environment where the organism lives.
Ecosystems can have a variety of habitats
Species: group of similar organisms that can mate to produce fertile offspring.
Niche: role in the environment
1. Type of food it eats (prey upon)
2. How it obtains food
3. General behaviors
4. Physical conditions needed for survival and reproduction
Energy Roles
An organism’s energy role in an ecosystem may be that of a producer, consumer,
or decomposer.
Producers: (autotrophs)
Energy enters an ecosystem as sunlight.
Plant, algae, microorganisms capture sunlight through photosynthesis to
make food.
Consumers:
Heterotrophs: organisms that cannot make their own food.
Depend on producers for food and energy.
3 types of consumers
Herbivores
Carnivores
Omnivores
Eat only plants
Eat only meat
Eat both plants and animals
Ex: deer, rabbits, cattle,
Ex. Lions, snakes, spiders
Ex. Crows, goats, humans
caterpillars
Scavenger: carnivore that feeds on dead organisms.
Ex. Vultures
Decomposers
Organisms that bread down wastes and dead organisms and return the raw
materials to the environment.
2 Major groups: (1) bacteria (2) fungi
return nutrients to the environment
Food Chains/ Food Webs
Energy from sunlight converts into sugar (glucose) and starch molecules by producers.
Energy is transferred to organisms that eat producers.
Energy is later transferred to another organism that eats the 1st organism
Food webs and food chains represent movement of Energy in the environment.
Food Chain (represents path of energy transferred from one organism to another.)
Ex.
Grass ------- Mouse ----- Hawk
(producer)
(1st consumer)
(2nd consumer)
---- (is eaten by)
Food Web
Represents overlapping food chains in an ecosystem
(refer to page 563 in textbook)
Energy Pyramids
When an organism eats food, it obtains energy
Energy is used to move, grow, reproduce
Part of the energy is available to the next level consumer
***Only 10% of the energy contained in one level of the food pyramid is
transferred to the next level.
90% of energy is used by the organism in life processes
-limits # of consumers of the next level of the pyramid.
Section 17-2 Biogeography
Different species live in different parts of the world
Continental Drift Theory ( approx 225 million years ago)
Older theory that suggests all of the continents were once one large land
mass “Pangea”. Later, the landmass began to break apart and pieces began to “drift”
away from each other.
 Organisms migrated over the huge landmass.
 Fossil evidence suggests that landmasses touched.
 Continental pieces fit together like a jigsaw puzzle
 Existing mountain ranges align when continents are fit together.
Means of Dispersal
1. Wind and Water ; move seeds from one place to another.
2. Organisms: carried seeds and dropped them (birds)
Section 17-3 Biomes ( see attached chart)
Section 17-4: Succession: Equilibrium in the Ecosystem
Community: all of the different organisms that live together in an area
Community in an ecosystem is in Equilibrium ( a state of balance, no sudden
changes in species populations)
Succession
-
A series of predictable changes that occur in a community over time.
Occur after a sudden change in Equilibrium from fires, volcanic eruptions,
floods, hurricanes, or human impact )
Primary Succession
o May take centuries
o Series of changes that occur in an area where no ecosystem previously
existed.
o Ex. Volcanic eruption where new land is created.
Refer to Fig. 23 p 587
1. no soil at first, only barren rock
2. Pioneer species: first species to populate an area
a. Lichen
b. Mosses
3. Pioneer species weather rocks and add nutrients to the new soil when they die.
4. Plant seeds carried by wind, birds, etc land in soil and begin to grow.
Plants will depend on type of biome
5. Trees and shrubs enter the area, small animals start to populate the ecosystem.
6. Changes will continue to occur until equilibrium is established.
Secondary Succession
o Series of changes that occur after a disturbance in an existing ecosystem.
o Ex. Fires
o Hurricanes
o Tornadoes
o Human activities (logging, farming, mining)
o Restores the ecosystem if left to do so
o May not be exactly the same as before
o More rapid recovery than primary succession
Refer to text, page 588, Fig 24
Ex. Abandoned Farmland
1. (after 2 years) weeds and wild flowers fill the plowed field
2. (after 5 years) small pine trees populate the field
3. (after 30 years) grown pine forest, new trees develop
4. (after 100 years) full mixed forest