Transcript Humans in the Biosphere

Humans in the
Biosphere
6-1
Changing the landscape
 Humans
depend on and participate in
food webs and chemical cycles.
 Activities that affect the biosphere
– Hunting and gathering
– Agriculture
– Industry
– Urban development
Hunting and Gathering
 Our
ancestors obtained food by
hunting and gathering
 They
hunted for birds and mammals,
and fished in rivers and oceans
 They also gathered seed, fruits and
nuts
 These activities changed the
environment.
Agriculture
 Agriculture
= farming
– One of the most important
developments in human history
 Why?
 Monoculture
is when a large field is
used to plant one type of plant year
after year
The Green Revolution
 The
introduction of monoculture and
the use of chemical fertilizers
became know as the green
revolution
 This
is because it greatly increase
the worlds food production.
Challenges for the Future
 Large
scale monoculture lead to
problems with pests and diseases
– Chemical pesticides can damage
beneficial insect, contaminate water and
accumulate in the environment
 Finding
enough water for irrigation
also became a problem
Industrial growth and urban
development
 These
have provided us with many of
the modern conveniences such as
homes, clothes, electronics,
machines cars, etc.
 The down side is the pollution put in
the air, water, and land due to this
 Also human growth takes up natural
habitats that puts stress on plants
and animals ability to survive.
6-2
Classifying Resources
 Environmental
goods and services
may be classified as either renewable
or nonrenewable.
Renewable resources
 Resources
that can regenerate if
they are alive or can be replenished
by biochemical cycles if they are
nonliving.
 Example
– a tree can grow in place
of an old tree that dies or is cut
down
Nonrenewable resource
A
resource that cannot be
replenished by natural processes.
 Example
– fossil fuels (coal, oil, and
natural gas) formed over hundreds
of millions of years from deeply
buried organic materials, when
they’re gone they’re gone forever.
Classifying a resource renewable
or nonrenewable
 This
depends on the context, a single
tree is renewable, a population of
trees in a forest ecosystem may not
be renewable.
 If a community of organisms
depends on the trees, the ecosystem
may change forever once those trees
are gone
Land Resources
 Land
is important b/c it gives us
space to live on and materials for
industry.
 It
also includes soil which crops are
grown in
 Soil
is renewable if managed
properly, but can be permanently
damaged if mismanaged
 Soil
erosion is the wearing away of
surface soil by water and wind
– Plowing the land removes roots and
plants which hold soil in place
A
combination of farming,
overgrazing, and drought has turned
productive areas in to deserts
– this is known as desertification
Forest Resources
 Forests
are important for the
products they provide and for the
ecological functions they perform
 Loss
of forest, deforestation, leads to
soil erosion which washes away
nutrients
Fish Resources
 Fish
and other animals that live in
water are valuable sources of food
for humanity
 Overfishing
means we are taking fish
out of the water faster than they are
reproducing
– Fish populations are decreasing because
of this
 Sustainable
development is a way to
try and maintain the worlds fish
supply
 There
are guidelines/rules which tell
fishermen how many and what size
fish they can catch
 Aquaculture,
the raising of aquatic
animals for human consumption, is
helping to sustain fish resources
Air resources
Air is a common resource that we use
every time we breathe, the condition of
the air affects people’s health
 Smog- a mixture of chemicals that occurs
as a gray-brown haze in the atmosphere.
 Smog is a pollutant, it is a harmful
material that can enter the biosphere
through the land, air or water.

Causes of air pollution
 The
burning of fossil fuels can
release pollutants into the
atmosphere
 Burning fossil fuels releases sulfur
and nitrogen compounds into the air
 Acid rain is caused by these
substances combining with water
vapor
6-3
Biodiversity
Biodiversity = total of the genetically
based variety of all organisms in the
biosphere
 Bio = life
Diversity = variety
 Biodiversity is the earths greatest natural
resource
 Species of many kinds have provided us
with foods, industrial products and
medicines – such as painkillers,
antibiotics, heart drugs, antidepressants,
and anticancer drugs

Threats to biodiversity
 Human
activities can reduce
biodiversity
– Altering (changing) habitats
– Hunting species to extinction
– Introducing toxic compounds into food
webs
– Introducing foreign species to new
environments
Habitat alteration
 When
humans develop land
habitants are destroyed
 As habitats disappear, the species
that live there disappear.
 When a habitat is split into pieces by
development it is called habitat
fragmentation.
Pollution
 Humans
add many toxic chemicals
into the environment that threaten
biodiversity
 Biological magnification –
concentrations of toxins increase in
organisms at higher trophic levels in
a food chain or web
 Each step up in the food chain
magnifies the toxin
Introduced Species
 Plants
and animals that seem
harmless are transported around the
world by humans.
 These
organisms can end up altering
native communities.
Invasive Species
 Species
that are introduced into new
habitats and reproduce rapidly.
 This
happens because their new
habitat lacks the parasites and
predators that normally control their
population “back home”.
Conservation


Conservation – the wise management of
natural resources, including preserving of
habitat and wildlife.
Conservation focuses on protecting
ecosystems, which will ensure that the
natural habitat and the interactions of
many different species are preserved at
the same time
6-4
Ozone depletion
 Ozone
layer protects the Earth from
the Sun’s Ultra-violet radiation
 Ozone
layer has been broken down
by pollutants put in the air by
humans, mainly cfc’s
Results of Ozone Depletion
 Ultra-violet
radiation causes cancer
– Skin cancer in humans has increase
over the last 20 years.
 Global
warming = the average
temperature of earth’s surface is
rising
Effects of Global Warming
 Higher
temperatures
 Sea levels may rise
 Ecosystems could change
Value of a Healthy Biosphere
 The
environment provides both
environmental and economic benefits
to humans
 Such as
-Insects that pollinate our crops
-Organisms that provide us with
new medicine
- new varieties of crops
How can we help
 Avoid
using excess water
(showering, watering plants)
 Plant trees to replace ones cut down
 Reuse/recycle trash and other
wastes
 Dispose chemicals in ways that don’t
harm ecosystems
 Cut down on use of fossil fuels