Transcript 7th gd Living Resources

Living Resources
Table of Contents
Environmental Issues
Forests and Fisheries
Biodiversity
The Search for New Medicines
Living Resources
Types of Environmental Issues
Three general categories of environmental issues are of
major concern: Resource use, Population growth, and
Pollution.
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Resource Use
Determining how to use our natural resources is a major
concern.
Natural resource —anything in the environment
that is used by people.
-Renewable resources —resources that are
either always available or naturally
replaced in a relatively short period of time.
Ex: sunlight, wind, fresh water, trees
-Nonrenewable resources —resources that
are not replaced in a useful timeframe. Ex:
oil, coal, natural gas and minerals.
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Population Growth
Human population growth is another
major concern.
-Human population grew very
slowly until about A.D. 1650.
After that, improvements in
medicine, agriculture and
waste disposal have
allowed it to grow much faster.
-Today, 6 billion people live on
this Earth.
-Will we have enough resources
to support them all?
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Pollution
Pollution is yet another major environmental concern.
Pollution is the contamination of Earth’s land, water or air.
-Causes: chemicals, wastes, noise, heat and light
-Related to both resource use and population
growth.
Example: burning fuels
Example: fertilizer use to feed growing
population
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Making Environmental Decisions
Deciding how to deal with these environmental issues is
no easy task.
Decisions must be made on many different levels:
personal
local
national
global
In all cases, the costs and benefits of every proposal
must be weighed carefully. This often involves
scientists, lawmakers and citizens.
Read pages 85-87
Living Resources - Environmental Issues
Identifying Main Ideas
As you read the section “Types of Environmental Issues,”
write the main idea in a graphic organizer like the one below.
Then write three supporting details that give examples of the
main idea.
Main Idea
Three types of environmental issues are…
Detail
Resource use
Detail
Population growth
Detail
Pollution
Living Resources - Environmental Issues
Links on the Environment
Click the SciLinks button for links on the environment.
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End of Section:
Environmental
Issues
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Living Resources
Chapter 3 is devoted to our living resources. We will look at
1. Managing our forests and our fisheries
2. Maintaining biodiversity throughout the world.
The large stump is from an oldgrowth California redwood tree. It
takes 400-500 yrs to get this large.
This Giant catfish is 9’ long and
weighs 646 lbs. Found in the Mekong
River, it may be the biggest freshwater
fish ever recorded (Source: NYTimes).
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Forest Resources
The value of our forests:
1. lumber
2. paper
3. household products
4. food
5. prevent flooding and soil erosion
6. produce oxygen
7. absorb carbon dioxide
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Managing Forests
Question: How much of the total land area of the
United States is covered with forests?
Answer: about 1/3 (300 million hectares)
Question: Are forests renewable or nonrenewable
resources?
Answer: renewable
However, to maintain our forests as a renewable
resource we must develop proper logging methods.
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Logging Methods
There are two major methods of logging:
1. Clear-cutting —cut down all the trees in an are
at once. This is quick, easy and safe for
the loggers. However, it is very damaging
to the environment.
2. Selective cutting —cut down only some trees,
leaving a mix of tree sizes and species.
This causes less damage to the
environment. However, it is more
expensive and more dangerous for the
loggers.
Living Resources - Forests and Fisheries
Managing Forests
Clear-cutting involves cutting down all the trees in an area at
once. Selective cutting involves cutting down only some
trees.
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Sustainable Forestry
The goal in managing forests is to provide a sustainable
yield.
Sustainable yield —an amount of trees that can
be harvested regularly without reducing
the future supply. To do this we must:
1. plant new trees to replace
harvested trees
2. harvest only at a rate that does
not exceed the growth replacement
3. log only small patches of forest
each year
Living Resources - Forests and Fisheries
Logging Methods Activity
Click the Active Art button to open a browser window and
access Active Art about logging methods.
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Fisheries
Fishery —an area with a large population of valuable
ocean organisms.
Examples: Grand Banks, Newfoundland
Georges Bank, New England
Monterey Canyon, California
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Question: Are fish renewable or nonrenewable
resources?
Answer: renewable
Question: Is it possible to “over-fish” an area?
Answer: Yes: Scientists estimate 70% of the
world’s major fisheries have been over-fished.
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Developing a Sustainable Yield
Techniques for managing a sustainable yield for fisheries
include:
1. Setting fishing limits —on number and size
2. Changing fishing methods —ban cyanide
poisoning and dynamite fishing; use nets with
larger mesh
3. Developing aquaculture —create fish farms
4. Finding new resources —find new fish species
that are good to eat
Living Resources - Forests and Fisheries
Using Prior Knowledge
Before you read, write what you know about forests and fish
resources in a graphic organizer like the one below. As you
read, write what you learn.
1.
2.
1.
2.
What You Know
Forests provide people with lumber and paper.
Commercial fishing boats harvest large amounts of fish.
What You Learned
Forests can be renewable resources.
Setting fishing limits, changing fishing methods, and
developing aquaculture techniques are ways to manage
fisheries for sustainable yields.
Living Resources
End of Section:
Forests and
Fisheries
Living Resources - Biodiversity
Diversity of Species
The number of different species in an area is called its
biodiversity.
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The Value of Biodiversity
There are many reasons why we should protect the
diversity of organisms on earth:
Economic value —plants, animals, and
other living organisms provide us with
food, clothing, medicines and other
products. Protecting their ecosystems can
also have economic value in tourism as
well.
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Ecologic value —all living things depend on other
living things to stay alive. This keeps
ecosystems in balance.
*Keystone species —a species that
influences the survival of many other
species in an ecosystem.
Example: Sea otters
(eat sea urchins---sea urchins eat kelp----when otters
were hunted to almost extinction the kelp died off too)
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Factors Affecting Biodiversity
Factors that affect biodiversity include:
Area —the larger the area; the more diversity.
Climate —diversity increases from the pole to the
equator. Tropical climates seem to support
more diversity.
Niche Diversity —more niches supports more
diversity. Example: coral reef vs. sand bar
Living Resources - Biodiversity
Factors Affecting Biodiversity
Factors that affect biodiversity in an ecosystem include area,
climate, and diversity of niches.
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Gene Pool Diversity
Gene Pool Diversity refers to diversity within a species.
-Genes —structures in an organism’s cell that carry
hereditary information.
-Gene Pool —All the different variations in the genes
of all the members of a species.
-Individual members of a species should be
genetically different from other members.
-Genetic differences such as differences in
color, size, and ability to fight disease will
allow a species to adapt better to changes in
its environment.
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Extinction of Species
Extinction —the disappearance of all the
members of a species. It is a natural
process---but seems to be increasing
dramatically in the last few centuries.
Endangered species —a species in danger
of becoming extinct in the near future.
Threatened species —a species that could
become endangered in the near future.
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Causes of Extinction
1. Habitat Destruction —this is the major cause of
extinction of most species.
Ex: Natural catastrophic event
Clear-cutting forests for lumber
Clearing land for city expansion or farming
Filling in wetlands
2. Habitat Fragmentation —breaking up a larger habitat
into smaller pieces
Ex: Road construction through a forest
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Causes of Extinction
3. Poaching —illegal killing or
removal of wildlife species from
their habitat.
4. Pollution —pollutants can build-up
in organisms and be passed
through the food chain. They can
kill or weaken organisms or cause
birth defects.
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5. Exotic Species —non-native
species introduced into a habitat
can out-compete with the native
species and push them to
extinction.
Rats accidentally
brought by sailors
to Hawaii—ate
Nene goose eggs
Nene Goose,
Hawaii’s state
bird is now
endangered.
Mongoose intentionally brought to Hawaii to kill
rats. Ate Nene goose eggs instead---easier.
Living Resources - Biodiversity
Endangered Species
Click the Video button to watch a movie
about endangered species.
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Protecting Biodiversity
To protect biodiversity we can either protect the individual
species or protect an entire ecosystem. Three approaches to
doing this are:
Captive Breeding —the mating of animals in
zoos or wildlife preserves. (Can be expensive).
Laws and Treaties —Endangered Species Act
and the Convention on International Trade
in Endangered Species have both saved
many species from extinction. (Can be hard to enforce)
Habitat Preservation —protect the whole ecosystem by
establishing parks and refuges. (Must be large area,
control pollution, poaching and exotic species)
Living Resources - Biodiversity
California Peregrine Falcon Recovery
The peregrine falcon, the
world’s fastest bird of prey, was
nearly extinct in the United
States in 1970. The pesticide
DDT was weakening peregrine
eggshells, so eggs rarely
hatched. In 1972, the United
States banned DDT. Use the
graph to answer questions
about the peregrine population
in California.
Living Resources - Biodiversity
California Peregrine Falcon Recovery
Reading Graphs:
What variable is plotted on
the x-axis? What variable is
plotted on the y-axis?
Time interval in years is on
the x-axis. Number of
breeding pairs of peregrine
falcons is on the y-axis.
Living Resources - Biodiversity
California Peregrine Falcon Recovery
Interpreting Data:
How did California’s
peregrine population change
from 1976 to 1998?
The population grew
steadily, except for a brief
drop around 1980, until
1994, when the number
of breeding pairs
remained the same for
the four following years.
Living Resources - Biodiversity
California Peregrine Falcon Recovery
Inferring:
Why do you think the
peregrine population grew
fairly slowly at first?
There were only a few
breeding pairs at first, and
they could produce only a
few young. These, in turn,
had to grow up before they
had a chance to breed. As
more pairs grew to breeding
age, more and more young
could be produced.
Living Resources - Biodiversity
California Peregrine Falcon Recovery
Predicting:
What might this graph have
looked like if DDT had not
been banned?
The graph probably would
have sloped downward from
left to right, possibly
reaching zero breeding
pairs.
Living Resources
Biodiversity Medicine
-Almost one half of all medicines sold today contain
chemicals originally found in wild organisms.
Ex: aspirin----bark of willow tree
digitalis for heart disease-----foxglove
vincristine for leukemia----rosy periwinkle
vinblastine for Hodgkin’s—rosy periwinkle
taxol for cancer---bark of Pacific Yew tree
-Most of these medicines are now made in a
laboratory so destruction of the plants are no longer
necessary. But without the plants, we would not have
been able to develop the medicines.
Living Resources - Biodiversity
More on Biodiversity
Click the Planet Diary button for an activity about biodiversity.
Living Resources - Biodiversity
Building Vocabulary
After you read this section, reread the paragraphs that
contain definitions of Key Terms. Use all the information you
have learned to write a meaningful sentence using each Key
Term.
Key Terms:
Examples:
biodiversity species
threatened
Species
The
biodiversity
that couldofbecome
ecosystems
endangered
can have
in great
the near
economic
future
are value.
called threatened species.
keystone
species
habitat destruction
A
keystone
species
is a species
that influences
the
The
major cause
of extinction
is habitat
destruction.
survival of many other species in an ecosystem.
Breaking larger habitats into smaller, isolated pieces,
Genes
are theisstructures
in an fragmentation.
organism’s cells that
or fragments,
called habitat
carry its hereditary information.
The
killing or removal
of wildlife
The illegal
disappearance
of all members
of aspecies
speciesfrom
from
their
habitats
is
called
poaching.
Earth is called extinction.
habitat fragmentation
gene
poaching
extinction
captive
breeding
endangered
species
Captive
breeding
is becoming
the matingextinct
of animals
zoos or
Species in
danger of
in theinnear
wildlife
preserves.
future are
called endangered species.
Living Resources
End of Section:
Biodiversity
Living Resources - The Search for New Medicines
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a what, how, who, when, or
where question for each heading. As you read, write the
answers to your questions.
Question
Answer
Why is biodiversity important to
medicine?
Biodiversity is important
because there may be
undiscovered medicines that
exist in nature.
What is the story of taxol?
Taxol is a cancer treatment drug
that comes from the bark of the
Pacific yew tree. Scientists are
concerned about the supply of
this tree.
How can we increase the
supply of taxol?
Today taxol can be reproduced
in the lab.
Living Resources - The Search for New Medicines
Links on Medicines From Plants
Click the SciLinks button for links on medicines from plants.
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End of Section:
The Search for
New Medicines
Living Resources
Graphic Organizer
Biodiversity
can be protected by
is valued for
Economic
value
Ecological
value
is threatened by
Habitat
destruction
Habitat
preservation
Captive
breeding
Poaching
Pollution
Laws
Poaching
Living Resources
End of Section:
Graphic Organizer