Transcript Computer Animations - kcpe-kcse

Ecology
Populations
Ecosystems
Succession
Humans and the Environment
Notes & Key: Ecology
Teacher Notes
Population
• Population size
– Refers to the number of individuals in a
population
– Factors that influence this size
• Abiotic – nonliving, such as temperature, moisture,
air, salinity, and pH
• Biotic – all the living organisms that inhabit the
environment
• Population density
– Refers to the number of individuals found
within a given area
– If too wide spread, they rarely encounter
each other – difficult to reproduce
• Dispersion
– Refers to the way in which the individuals of
the population are arranged
• Even – individuals are located at equal intervals
• Clumped – bunched together in clusters
• Random – location of each individual is determined
by chance
• Population Growth – population grows
when more individuals are born than die
• Carrying capacity – when a population has
reached the maximum size that the
environment can support
– Size is determined by limiting factors
– Food, water, shelter
• Populations living areas
– Habitat = the area in which an organism lives
– Niche = the role the organism has in an
ecosystem
• Population relationships
– Symbiosis – close association between two
different types of organisms – a scientific
‘living together’
• Mutualism – both organisms benefit (lichen)
• Commensalism – one organism benefits and the
other is neither harmed nor helped (epiphytes)
• Parasitism – one organism benefits and the other
is harmed (flea)
Ecosystems
• Energy Flow
– Producers - make their own food (green
plants, algae, some bacteria)
– Consumers - obtain their food from others
• Herbivores – primary consumers that eat plants
• Carnivores – secondary consumers that eat flesh
• Omnivores – secondary or tertiary consumers that
eat plants and flesh
• Decomposers – eat dead and decaying organisms
• Food Chain
– Trophic levels
• Clover
• Rabbit
• Snake
• Hawk
• Food Web
– Food chains that interconnect
– and overlap
• Pyramid of biomass
– Total mass of organisms at each trophic level
• Pyramid of numbers
– Number of organisms at each trophic level
• Pyramid of energy
– Amount of energy at each trophic level
– Each trophic level receives ~ 10% from the
next higher level
• Cycles
– Water cycle
• Nonliving
– Condensation, precipitation, evaporation
• Living
– Absorption, transpiration
• Carbon cycle
– Atmospheric carbon
– Photosynthesis
– Cellular respiration
• Nitrogen cycle
– Atmospheric nitrogen
– Nitrogen-fixing bacteria
– Nitrates
– Nitrites
– Plants
– Animals
– Decomposers
• Oxygen cycle
– Oxygen in air and water
– Cellular respiration
– Water
– Photosynthesis
Succession
• Populations in an area are replaced by
other populations
– Organisms make the environment less
conducive for their existence and more
conducive for the next level
• Primary succession – where life did not
exist before
– Pioneer species
– Continuing species change
– Climax community
– Ex. lichen, grasses, small bushes, small trees,
mature softwoods (pines, balsams, firs),
mature hardwoods (oaks, hickories)
• Secondary succession – where a prior
community was destroyed (by fire, flood,
volcanic eruption, abandoned farming,
mining, logging, etc.)
– Pioneer species
– Continuing species change
– Climax community
Humans and the Environment
• Conservation – Wise management of the
Earth’s natural resources
– Renewable resources
– Nonrenewable resources
• Renewable resources
– Wildlife
• Many threatened or endangered
• Extinction occurs when a species disappears from
Earth
• Habitat destruction is major cause
– Forests
• Becoming smaller due to increased demand for wood and
wood products
• Deforestation occurs where large areas of forest are cut and
cleared. Ex. tropical rainforests
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–
–
–
Cut and burned to clear land for farming
Topsoil is thin, good for one, or maybe two, years
Then more must be cleared
When land is cleared, rain ceases as trees caused the rain
through transpiration
– Land becomes a desert
Reforestation is a solution
• Soil – good soil is needed to grow plants
for food and for fibers to make cloth
– Erosion can be prevented
• Windbreaks
• Contour plowing
• Terrace plowing
• Strip cropping
• Crop rotation
• Nonrewable resources
– Water
• Most important
• Cannot live without it
• Watersheds
• Desalination
Fossil Fuels
Coal, natural gas, oil
Alternative energy forms
solar energy
nuclear energy
wind power
geothermal energy
water energy
• Pollution
– Air pollution
• Most comes from burning fossil fuels
• Smog – smoke and fog
• Acid rain – oxides from burning fossil fuel combine with
moisture in air
• Temperature inversion
– Layer of warm air becomes trapped between layers of cool air
– Air pollutants become trapped in cool air
– Do not rise form the earth, stay near ground
– Water pollution
• Agricultural runoff
• Industrial waste products
– One major example is hot water
– Causes thermal pollution
– Hot water holds less oxygen than cold water