Transcript Humans in the Biosphere

Humans in the Biosphere
Ch. 6
1.37, 1.38, 1.40, 1.41, 1.43, 1.45, 1.46
Changing Landscape
• Many species of
organisms have
become extinct or
scarce because of
human actions of
resource use and
cutting down trees.
Human Activities
• We affect the
biosphere by:
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Hunting and Gathering
Agriculture- farming
Industry
Urban Development
Hunting and Gathering
In N. America
mammoths,
giant ground
sloths, sabertooth cats
extinct.
Cheetahs,
zebras, and yaks
disappeared.
Agriculture
• Began about 11,000
years ago at the end
of the Ice Age.
• Monoculture- large
fields are planted with
a single variety year
after year.
• Fertiliziers, chemicals
The Green Revolution
• Modern agricultural
techniques were
introduced, increasing
the world’s food
supply.
• Provided better
nutrition.
• Ecological challenges
– Insect pest and
diseases- add
pesticides.
– Finding enough water
for irrigation.
Industrial Growth and Urban
Development
• During 1800’s the
Industrial Revolution
took off.
• What are some ways
the Industrial
Revolution has
effected the
environment?
Resources
• Renewable- can
regenerate if they are
alive, or can be
replenished by
biochemical cycles if
they are non-living.
• Water, other
examples?
• Are they unlimited?
• Non-renewablecannot be replenished
by natural processes.
• Fossil fuels.
Sustainable Development
• Way of using natural
resources without
depleting them, and
of providing for
human needs without
causing long term
environmental harm.
• Human activities can
affect the quality and
supply of renewable
resources such as
land, forests,
fisheries, air and fresh
water.
• How?
Land Resources
• Soil is a renewable
resource if managed
properly.
• Fertile soil- mixture of
sand, clay, rock
particles and humus
(material decayed
organisms.)
• Soil erosion- wearing
away of soil surface
by water and wind.
• Desertificationoccurs in dry climates
by farming,
overgrazing and
drought.
Forest Resources
• Wood is still used in
many parts of the world
for burning for energy.
• Slashing and burning of
forests to build homes or
for agriculture.
– In the tropical rainforests,
we lose many chances to
find cures for diseases.
• Deforestation- loss of
forests.
– Severe erosion when
exposed to heavy rains.
– Erosion washes away
nutrients in topsoil.
– Grazing or plowing after
deforestation causes
permanent changes to soil
and microclimate that can
prevent regrowth of trees. .
Fishery Resources
• Overfishing- reduces
number of fish
because harvesting
fish faster than they
can reproduce.
• There are guidelines
for US commercial
fishing.
• Aquaculture- raising
of aquatic animals for
human consumption.
Air resources
• Smog- mixture of
chemicals that occurs as
a gray-brown haze in the
atmosphere.
• Primarily due to
automobile exhausts and
industrial emissions.
• Pollutant- harmful
material that can enter
the biosphere through the
air, land, and water.
• Acid Rain- occurs when
the burning of fossil fuels
combines with water
vapor in the air and form
nitric and sulfuric acids.
– Affects fish reproduction
and plants if acidic enough.
Freshwater Resources
• Americans use
billions of liters of
freshwater daily.
• Important to protect it
from chemicals and
pollutants.
Biodiversity
• Biodiversity is the sum
total of the genetically
based variety of all
organisms in the
biosphere.
• Ecosystem diversityhabitats, communties and
ecological processes in
living world.
• Species diversitynumber of species in the
biosphere. 1.5 million
named and identified.
• Genetic diversity- sum
total of all of the different
forms of genetic
information carried by all
organisms living.
Biodiversity is one of Earth’s
greatest natural resources.
• Species of many kinds have provided us
with foods, industrial products and
medicines- including painkillers,
antibiotics, heart drugs, antidepressants,
and anticancer drugs.
– Rosy Perwinkle plant helps treat cancers.
Threats to Biodiversity
• Human activity can
reduce biodiversity by
alternating habitats,
hunting species to
extinction, introducing
toxic compounds into
food webs, and
introducing foreign
species to new
environments.
• Extinction- occurs when
species disappears from
all or part of its range.
• Endangered speciespopulation size is
declining in a way that
takes place it in a danger
of extinction.
• Examples?
Habitat Alternation
• How do humans alter
habitats?
• Habitat fragmentation
is the splitting of
ecosystems into small
fragments.
• What happens to the
animals in the
habitats?
Demand for Wildlife Products
• How have humans
pushed animals to
extinction?
• Examples?
Pollution
• Biolgoical magnificationToxic compounds
acculumate in the tissue
of organisms as it travels
through the food chain.
• DDT- fist widely used
pesticide.
– Nonbiodegradable
– When it is picked up by
organisms, they do not
eliminate it from their body.
Invasive Species
• In 1988, small
freshwater zebra
mussels were
introduced to Lake
Erie from Europe.
• They spread to all
great lakes in less
than 10 years.
• They compete with
other species for
food.
• They clog up waterintake pipes and
farm-irrigation pipes.
• One benefit- filterfeeding action h as
made water cleaner.
• Gypsy moths
1.38
Conserving Biodiversity
• Why is it important to
preserve entire
ecosystems?
• See the timeline on page
154 for efforts made to
improve the earth.
• Today, conservation
efforts focus on protecting
entire ecosystems as well
as single species.
Protecting an ecosystem
will ensure that all the
natural habitats and the
interactions of many
different species are
preserved.