Download Biosphere lecture notes

The Biosphere
and
Human Impact on Ecosystems
Chapters 15 - 16
Chapter 15
The biosphere is the portion of Earth
that is inhabited by life.
• The biosphere includes all
ecosystems and biota (all the living
things in the biosphere)
• There are 3 other Earth systems:
– hydrosphere—water, ice, and
water vapor
– atmosphere—air blanketing
Earth’s solid and liquid surface
– geosphere—geologic features
above and below Earth’s surface
Climate is the prevailing weather of a region.
• Climate is the long-term pattern of weather
conditions.
– average temperature
– precipitation
– relative humidity
• Key factors shape an area’s climate.
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–
–
–
temperature
sunlight
water
wind
A microclimate is
the climate of a
small specific place
within a larger
area.
Earth has three main climate zones.
• The three main zones are the polar, tropical, and
temperate climates.
– polar zone: the far northern
and southern regions of
Earth
– tropical zone: surrounds
the equator
– temperate zone: the
wide area in between
the polar and tropical zones
• The angle of the Sun’s rays help determine an area’s climate.
•
•
•
Earth’s tilt on its axis plays a role in
seasonal change.
Solar heating causes movements in
both water and air.
– wind
– ocean currents
Earth’s rotation also has effects on
the winds and currents
• Mountains have an effect on climate.
– Precipitation occurs on the side of the mountain facing the wind.
– On the downwind side, drier and cooler air produce a rain shadow.
– A rain shadow is an area of decreased precipitation.
western slope
eastern slope
Earth has 6 major biomes.
•
Biomes are land-based, global communities of organisms.
• Tropical rain forest
biomes produce
lush forests.
– warm temperature
– abundant precipitation all
year
– Nutrient poor soil
Source: World Meteorological Organization
• Grassland biomes are where the primary plant life is grass.
• 2 types of grasslands:
1.
Temperate grasslands are dry and warm during the summer; most precipitation
falls as snow.
Rapid City, South Dakota
Source: National Oceanic Atmospheric Administration
2. Tropical grasslands (aka Savannah) are warm through the year, with
definite dry and rainy seasons.
• Desert biomes are
characterized by a very
arid climate.
Tucson, Arizona
– very low amount of precipitation
– Largest fluctuation in daily
temperature
Source: National Oceanic Atmospheric Administration
• Temperate forest biomes include deciduous forests and coniferous forests.
– Temperate deciduous forests have hot summers and cold winters.
– Deciduous trees are the dominant plant species.
– Deciduous trees lose leaves in fall.
Burlington, Vermont
Source: National Oceanic Atmospheric Administration
•Coniferous forest trees
keep needles all year.
• The taiga biome is located in
cooler northern climates.
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–
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Banff, Canada
Aka boreal forest
long winters and short summers
small amount of precipitation
Contains coniferous forest
Source: Environment Canada
• The tundra biome is found
in the far northern
latitudes with long winters.
Barrow, Alaska
– winter lasts 10 months
– limited precipitation
– permafrost
Source: National Oceanic Atmospheric Administration
Polar ice caps and mountains are not considered biomes.
• Polar ice caps have no soil, therefore no plant community.
• The climate and organisms found on mountains change as the
elevation changes.
Coastal waters contain unique habitats.
• Coral reefs are found in warm waters.
• Plankton make up most of the biomass.
– Phytoplankton is single celled algae. Form base of aquatic food web
– Zooplankton are planktonic animals. Feed on phytoplankton
• Kelp forests are found in cold, nutrient-rich waters.
– large communities of seaweed
– great amount of biomass
Estuaries are dynamic environments where
rivers flow into the ocean.
•
An estuary is a partially enclosed body of water.
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–
–
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•
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Estuaries are highly productive ecosystems.
Estuaries provide a protected refuge for many species.
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–
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mixture of fresh water with salt water
Chesapeake Bay in Maryland
Mobile Bay in Alabama
Louisiana bayous
birds migration
spawning grounds
Estuaries are primarily threatened by land development.
Chapter 16
KEY CONCEPT
As the human population grows, the demand for Earth’s resources increases.
Earth’s human population continues to grow.
• Earth’s human carrying capacity is unknown.
• Technology has helped to increase Earth’s carrying capacity.
– gas-powered agriculture equipment increases food production
– medical advancements decrease death rate and spread of disease
– Transportation moves food and materials around the world
The growing human population exerts pressure on
Earth’s natural resources.
• Nonrenewable resources are used faster than they form.
– coal
– oil
•Renewable resources
cannot be used up or can
replenish themselves over
time.
– wind
– water
– sunlight
• Growing use of nonrenewable resources may lead to a crisis.
• Resources must be properly managed.
• An ecological footprint is the amount of
land needed to support a person.
•
The land must produce and maintain enough
– food and water
– shelter
– energy
– waste
•What is your ecological footprint?
•Find out at: www.myfootprint.org
• Several factors affect the size of the ecological footprint.
– amount and efficiency of resource use
– amount and toxicity of waste produced
Pollutants accumulate in the air.
• Pollution is any undesirable
factor added to the air,
water, or soil.
• Smog is one type of air
pollution.
– sunlight interacts with
pollutants in the air produced
by fossil fuel emissions
– made of particulates and
ground-level ozone
• Smog can be harmful to human health.
•
Acid rain is caused by fossil fuel
emissions.
– produced when pollutants in the
water cycle cause rain pH to drop
(more acidic)
– can lower the pH of a lake or
stream and kill fish
– can harm trees
Air pollution is changing Earth’s biosphere.
• The levels of atmospheric carbon dioxide rise and fall
over time.
• High levels of carbon dioxide are typical of Earth’s
warmer periods.
• The greenhouse effect slows the release of energy from
Earth’s atmosphere.
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–
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sunlight penetrates Earth’s atmosphere
energy is absorbed and reradiated as heat
greenhouse gases absorb longer wavelengths
Greenhouse
gas molecules
rerelease
infrared
radiation
carbon dioxide
(CO2)
methane (CH4)
water (H2O)
• Global warming refers to the trend of increasing global temperatures.
• CFCs: Chlorofluorocarbons that deplete
ozone layer.
North Pole
Water pollution affects ecosystems.
• Pollution can put entire freshwater ecosystems at risk.
•Indicator species provide a sign of
an ecosystem’s health.
– Amphibians
– top predators
Biomagnification causes accumulation of
toxins in the food chain.
• Pollutants can move up the
food chain.
– predators eat contaminated
prey
– pollution accumulates at
each stage of the food chain
• Top consumers, including
humans, are most affected.
The impact of a growing human population threatens biodiversity.
Preserving biodiversity is important to the future of the biosphere.
• The loss of biodiversity has long-term effects.
– loss of medical and technological advances
– extinction of species
– loss of ecosystem stability
Loss of habitat eliminates species.
• Habitat fragmentation prevents an organism from
accessing its entire home range.
– occurs when a barrier forms within the habitat
– often caused by human development
• Habitat corridors are a solution to the problem.
– corridors can be road overpasses or underpasses
– allow species to move between different areas of habitat
Introduced species can disrupt stable relationships in an ecosystem.
•
An introduced species is one that
is brought to an ecosystem by
humans.
– accidental
– purposeful
•
•
Invasive species can have an
environmental and economic
impact.
Invasive species often push out
native species because there is
no natural predator.
Southeastern Asia Burmese
python in Florida Everglades
Asian
kudzu in
southeast
US
European rabbits in Australia
Sustainable development manages resources for
present and future generations.
• Sustainable development meets needs without
hurting future generations.
– resources meet current needs
– resources will still be available for future use
• The timber industry has started to adopt sustainable practices.
• Global fisheries have adopted several sustainable practices.
– rotation of catches
– fishing gear review
– harvest reduction
– fishing bans
Conservation practices focus on a few species but
benefit entire ecosystems.
• The Endangered Species Act
works to protect individual
species from extinction.
• A listed species is often
called an umbrella species.
– the habitat in which the
species lives must be
protected
– other species are protected
because they share the
ecosystem
Protecting Earth’s resources helps protect our future.
• The Environmental
Protection Agency (EPA)
was created in 1970.
• The EPA develops
policies and regulations
to protect the
environment.
• Legislation helps to
protect the environment
and endangered
species.
– Clean Air Act
– Clean Water Act
– Endangered Species Act
• The National Park Service helps manage public lands by
protecting natural resources and animals.
• There are several ways that people can help protect the environment.
– control population growth
– develop sustainable technology and practices
– protect and maintain ecosystems