Transcript Human Impact on ecosystems

AKS Standards
11d - assess and explain human activities that
influence and modify the environment such as
global warming, population growth, pesticide use,
and water/power consumption
HUMANS IN THE BIOSPHERE
• The human population is still growing, but the earth is not, and this places
increasing demands on Earth’s air, water, land, and living things
• Understanding how humans interact with the biosphere is crucial to
protecting these resources
• Industry & technology give humans a strong advantage in competing w/ other
species for limited resources
• Human activity uses as much energy as all of Earth’s other multicellular
species combined
• Hunting and gathering, agriculture, industry and urban development have
significantly transformed the biosphere
• Human activities can change the flow of energy in an ecosystem and
reduce the ability of ecosystems to recycle nutrients.
THE GREEN REVOLUTION
• The green revolution was introduced in the 1950’s by the
government as an effort to greatly increase the yields of rice,
wheat, and other crops
 Using highly productive varieties of certain crops
 Using monoculture – large fields cleared, plowed, and planted with the
same crops year after year
 Relied on pesticides, fertilizers, and large equipment to support large
growing areas
 Benefits: increased food production
 Problems: depletion of energy and water supplies, pest species enabled to
reproduce on a vast scale, pesticides can be potentially harmful, fertilizers
can interfere with food webs and biogeochemical cycles
THE INDUSTRIAL REVOLUTION
• The era known as the Industrial Revolution was a
period in which fundamental changes occurred in
agriculture, textile and metal manufacture,
transportation, economic policies and social structure
(1760-1850).
Dense human communities
Human waste products
Reduction in habitats
Pollution
Overuse of wildlife products
EARTH’S HUMAN POPULATION CONTINUES TO GROW
Our prediction of Earth’s human carrying
capacity has changed over time.
Although we do not know of a fixed limit to
the number of people that Earth can
support, some limit must exist.
As humans have modified their
environment through agriculture,
transportation, medical advances, and
sanitation, the carrying capacity of
Earth has greatly increased.
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THE GROWING HUMAN POPULATION EXERTS PRESSURE
ON EARTH’S NATURAL RESOURCES
Renewable Resources: those that replenish themselves quickly enough so that they will not be
used faster than they can be produced.
• Examples include: oil & coal
Nonrenewable Resources: natural resources that are used more quickly than they can be formed.
• Examples include: wind energy, solar energy, and resource renewable through regrowth or
reproduction (as long as they are not used faster than their regrowth)
EFFECTIVE MANAGEMENT OF EARTH’S RESOURCES WILL
HELP MEET THE NEEDS OF THE FUTURE
Earth’s carrying capacity depends on how much land is
needed to support each person on Earth.
The amount of land necessary to produce and maintain
enough food, water, shelter, energy, and waste is called
an ecological footprint.
Individuals and populations vary in their use of resources
and production of waste, and therefore in the size of
their ecological footprint.
The average U.S. citizen’s ecological footprint covers an area
larger than 24 football fields and is one of the largest in
the world.
CRITICAL THINKING ACTIVITY: CONNECTING CONCEPTS
The progressive increase in Earth’s human carrying capacity came from
advances in technology. What density-independent and densitydependent limiting factors may prevent the human population from
continued growth?
 Disease, lack of food, limited water supplies (density-dependent)
 Exhaustion of nonrenewable resources, medical and cultural practices
(density-dependent)
AKS Standards
11d - assess and explain human activities that
influence and modify the environment such as
global warming, population growth, pesticide use,
and water/power consumption
POLLUTANTS ACCUMULATE IN THE AIR
Pollution describes any undesirable factor, or
pollutant, that is added to the air, water, or
soil. The harmful effects of pollutants can be
immediate or delayed, but these effects may
add up over time and can disrupt the
function of ecosystems.
Smog is a type of air pollution caused by the
interaction of sunlight with pollutants
produced by fossil fuel emissions.
ACID RAIN
The chemicals produced by the burning
of fossil fuels become part of the
ecosystem and can change the
products of natural cycles.
For example, nitrogen oxides and sulfur
oxides from fossil fuel emissions can
lead to the formation of acid rain.
By decreasing pH levels in lakes and
streams, acid rain threatens water
supplies and species habitat.
Ecological Effects from Acid Rain in Lake System
•
Changes begin to occur as soon as a lake starts to lose it
natural bases or alkalinity.
1. A large reduction in the number of plankton &
invertebrates.
2. The rate of decomposition of organic matter decreases
3. Direct effects on fishes reproductive cycles.
4. A calcium deficiency in fish leads to bone malformation.
5. Fish can suffocate as their gills become clogged with
aluminum hydroxide.
6. Songbirds are effected by eating insects contaminated
with toxic metals.
THE GREENHOUSE EFFECT
GLOBAL WARMING
ANIMATED BIOLOGY: GREENHOUSE WARMING
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t5/bio_ch16_0491_ab_co2fx.html
AKS Standards
11d - assess and explain human activities that
influence and modify the environment such as
global warming, population growth, pesticide use,
and water/power consumption
WATER POLLUTION AFFECTS ECOSYSTEMS
Algae are microscopic plants that are usually aquatic,
unicellular, and lack true stems, roots, and leaves.
Algal blooms occur in both marine and freshwater
environments when an algal species outcompetes
other species and reproduces rapidly.
An algal bloom can still kill fish and other aquatic life by
decreasing sunlight available to the water and by
using up all of the available oxygen in the water.
Blooms can be caused by several factors. An increase
in nutrients can cause algae growth and
reproduction to increase dramatically into a bloom
just as fertilizing a lawn makes the grass grow
faster.
BIOMAGNIFICATION CAUSES ACCUMULATION OF
TOXINS IN THE FOOD CHAIN
In biomagnification, there is a tendency for
pollutants to concentrate as they move from
one link in a food chain to another…top level
carnivores suffer the most harmful effects of
biomagnification.
Know and be able to explain how
biomagnification of DDT affected the health of
large birds of prey.
INTERACTIVE REVIEW: WATER QUALITY
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Complete this interactive
review using your virtual
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maps are an excellent way to
organize your thoughts and
review material!
AKS Standards
11d - assess and explain human activities that
influence and modify the environment such as
global warming, population growth, pesticide use,
and water/power consumption
PRESERVING BIODIVERSITY IS IMPORTANT TO
THE FUTURE OF THE BIOSPHERE
Biodiversity is the sum total of the genetically based variety of all organisms in
the biosphere
 Biologists have identified ~1.5 million species and estimate that there are
millions more.
 Biodiversity is one of the Earth’s greatest natural resources – food,
industrial products, medicines!!!!
Ecosystem diversity includes the variety of habitats, communities, and
ecological processes in the living world
Species diversity is the number of different species in the biosphere
Genetic diversity is the sum total of all the different forms of genetic information
carried by all organisms living on Earth today
LOSS OF HABITAT ELIMINATES SPECIES
Development often splits
ecosystems into pieces
(habitat fragmentation). This
results in remaining pieces of
habitat becoming biological
“islands”. Fewer species can
survive here and they are
more vulnerable to further
disturbances or climate
changes.
INTRODUCED SPECIES CAN DISRUPT STABLE
RELATIONSHIPS IN AN ECOSYSTEM
 One of the largest threats to
biodiversity is the accidental or
intentional introduction of new plants
and animals to areas around the world
by humans.
 These can often become invasive
species (a new species able to
reproduce rapidly because their new
habitat lacks the natural population
controls they face in their old habitat).
 Cane Toads in Australia
 Kudzu in America
 African Bees in South America
 Burmese Python in Florida
Everglades
CONSERVING BIODIVERSITY
Conservation describes the wise management of natural
resources
Today, conservation efforts focus on protecting entire
ecosystems as well as single species
 Most often, the need to protect biodiversity is greatest in
countries that are least able to do so (these are known as “hot
spots”) – immediate danger of extinction of species as a result of
human activity
 Example: rainforests are found in developing countries
BIOLOGICAL HOT SPOTS
In an effort to locate problem areas and set up a list of conservation priorities, conservation
biologists identify “hot spots”…places where significant numbers of habitats and species are in
immediate danger of extinction as a result of human activity.
WEBQUEST: INVASIVE SPECIES
http://www.classzone.com/cz/ot/bio_webquest/16/intro.jsp
DATA ANALYSIS ONLINE
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ch16_frog_recovery/index.html
AKS Standards
11d - assess and explain human activities that
influence and modify the environment such as
global warming, population growth, pesticide use,
and water/power consumption
SUSTAINABLE DEVELOPMENT MANAGES RESOURCES
FOR PRESENT AND FUTURE GENERATIONS
• Sustainable use is a way of using natural resources at a rate that does not deplete
them
• Land resources
• Forest resources
• Ocean resources
• Air resources
• Water resources
• A sustainable system operates without causing long-term harm to the ecological
resources on which it depends
• Example: alternative methods of pest control that do not involve harmful chemicals
CRITICAL THINKING ACTIVITY: INTERPRETING VISUALS
ANIMATED BIOLOGY: HUMAN EFFECTS ON A FOOD WEB
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t5/bio_ch16_0507_ab_foodwbfx.html