Download 1.1 Safety in the Science Classroom

3.1 How Changes Occur Naturally
in Ecosystems
• When an organism is born, it belongs to a ___________ ,
but it also is born with unique characteristics.
 Sometimes, these unique characteristics give organisms an advantage within
their niche. For example, a salmon with a slightly larger tail may be able to swim
a little faster or a little farther in a river.
• ___________ ___________ is the process where
individuals with advantages are better able
to reproduce and pass along their traits.
 Those with ___________ characteristics have
less chance to reproduce and pass along
A salmon with a large tail may be able
to swim faster and farther.
their traits.
 A salmon with a smaller tail may never have a chance
to spawn because it cannot swim to the correct location. See pages 108 - 109
(c) McGraw Hill Ryerson 2007
How Organisms Adapt to Change
• The Galapagos Islands, off the coast of Ecuador, are a
famous example of natural selection.
 Many species on these islands are very similar to each other
but different from species on the South American continent.
 There are 13 species of finches on the islands.
 Each is descended from a finch species from the
mainland.
 Each species has unique characteristics that allow
it to thrive in its own niche and not compete with
other finches for resources.
Galapagos
finches
• ___________ describes the type of
natural selection where many different
species appear from one original species.
See page 110
(c) McGraw Hill Ryerson 2007
How Ecosystems Change Over Time:
Primary Succession
•
___________ succession refers to the changes in the biotic
characteristics in an area over time.
 There are two types of ecological succession:
primary succession and secondary succession.
1. ___________ succession begins with bare rock
such as where glaciers scrape away dirt
or a volcano erupts.
Bare rock.
 Wind carries spores of lichens and organisms that can survive and eventually,
combined with the weathering of rock, help form soil.
 The first organisms to survive and reproduce are pioneer species.
 Pioneer species alter the abiotic and biotic environment in some way.
 Soil improves, plants are able to grow and animals begin to appear.
 Primary succession occurs in all parts of the world.
 This stage can last for hundreds of years, until a mature community eventually
forms.
See pages 111 - 113
(c) McGraw Hill Ryerson 2007
How Ecosystems Change Over Time:
Secondary Succession
•
Mature communities are very stable and can appear
to be unchanging over long periods of time.
 These are also known as climax communities, but “mature” correctly implies
that there are still changes occurring.
2. ___________ succession occurs after a major disturbance in an area
that already has soil and once had living organisms.
 Forest fires are the most common reason for
secondary succession.
 The soil remains for plant growth and contains
seeds, micro-organisms, earthworms,
and insects.
 Secondary succession is much more rapid than
primary succession because soil, seeds and
insects are already present.
Secondary succession.
See page 114
(c) McGraw Hill Ryerson 2007
How Natural Events Affect Ecosystems
• Many other disturbances can affect mature communities.
• ___________
 Water is not contained within natural or artificial barriers.
 Floods generally occur in locations where water levels can change rapidly.
 Flooding can result in soil erosion as well as the spread of pollutants and
harmful bacteria associated with wastes.
 Climate change and global warming may be increasing incidents of flooding.
 A tsunami occurs when huge waves from large earthquakes or volcanic
eruptions flood coastal areas.
• ___________
 Drought occurs when an area receives a lower than average amount of
rainfall over a long period of time.
 Prolonged drought can have severe effects on organisms.
See pages 115 - 116
(c) McGraw Hill Ryerson 2007
How Natural Events Affect Ecosystems
(continued)
• ___________ infestations
 Many insects play important roles in their ecosystems.
 Even insects that appear destructive, such as the
mountain pine beetle, actually play a role in the
renewal of the forest.
 The beetles have a symbiotic relationship
with a species of fungus that inhibits the
Mountain pine beetle.
trees’ ability to use resin for protection.
 However, when normal conditions are changed, infestations can occur.
 Trees can be stressed from overcrowding drought or animal grazing and
do not resist the insects as effectively.
 A warmer climate and lack of forest fires allows the insects to spread
much more effectively than in the past.
 Not only are the trees affected, but so is the entire forest ecosystem, as well
as any human industries relying on the forest.
See page 117
Take the Section 3.1 Quiz
(c) McGraw Hill Ryerson 2007
3.2 How Humans Influence Ecosystems
• ___________ are ecosystems that contain completely waterlogged
soil for long periods of time.
 Not only do wetlands contain high biodiversity, but they also filter many
impurities out of the water that slowly flows through them.
 For this reason, they are sometimes called the “kidneys” of Earth.
 Because they hold large amounts of water, they can help prevent flooding.
• Human ___________ has caused many
British Columbia wetlands to disappear.
Wetlands are vital ecological
features in British Columbia.
 In the past 100 years:
 Up to 70 percent of the wetlands in the lower
Fraser Valley have been lost.
 Up to 85 percent of the wetlands in the South
Okanagan have been lost.
See pages 122 - 123
(c) McGraw Hill Ryerson 2007
Understanding Sustainability
• ___________ is the ability of an ecosystem to sustain
ecological processes.
 These processes enable ___________ and keep the ecosystem healthy.
 Sustainability can also include people using an ecosystem to meet their needs today
without reducing the function or health of the ecosystem in the future.
 Sustainable practices maintain, or even improve, healthy ecosystems.
 Economic opportunity, biodiversity, and ecosystem health are all possible.
Returning young coho salmon
to rivers near Port Alice can
help maintain sustainability.
See page 125
(c) McGraw Hill Ryerson 2007
The Effects of Land and Resource Use
• “___________ use” refers to how humans use land for urban
development, agriculture, industry, mining, and forestry.
 All of the land around us, even in cities, was once a part of an ecosystem.
• “___________ use” refers to the ways we obtain and use naturally
occurring materials.
 Most products you use every day involve the use of some natural resources in
their production.
• If the land and resources are not used directly, they are often
processed and exported to other places for use.
The processing and export of resources like
lumber, coal, and sulfur are very important
to British Columbia’s economy.
See page 126
(c) McGraw Hill Ryerson 2007
Habitat Loss
• Humans have encroached on natural ecosystems very ___________
in the past 150 years.
 As a result of this expansion, habitats have been lost or fragmented.
 “___________ loss” refers to loss of habitats due to human activities.
 “___________ fragmentation” is the splitting of large habitats into many
smaller ones, resulting in disrupted natural activities for plants and animals.
Habitat loss (left) and habitat fragmentation (right)
reveal the effects of human activities on ecosystems.
See page 126
(c) McGraw Hill Ryerson 2007
Habitat Loss (continued)
See page 127
(c) McGraw Hill Ryerson 2007
The Effects of Deforestation
• ___________ is the clearing or logging of forests for human use.
 The resulting barren land is never reclaimed or replanted.
 The agricultural crops that are planted are often one species.
 This reduces biodiversity and leaves the crop vulnerable to pests or
disease.
 Deforestation is still occurring in many tropical
rainforests.
 Deforestation results in soil degradation.
 ___________ degradation occurs when moving wind
and water
erode topsoil and leave bare land behind.
Converting a tropical
 Topsoil, the upper layer of soil, is where most
rainforest into farmland.
of the nutrients, water, and air are found
for plant growth.
See page 128
(c) McGraw Hill Ryerson 2007
The Effects of Agriculture
• If fields are left ___________ during non-planting seasons,
water and wind erosion can occur.
• In areas like southwestern British Columbia, the soil can become
compacted.
 Soil particles are squeezed together due to farm animals or vehicles.
 There is no room for water or air to enter the soil. Farm animals, such as these
cows, can compact soils.
 Water then runs off the soil instead of soaking
in, resulting in loss of water, increased erosion,
and the addition of farm fertilizers and pesticides
to the ecosystem.
 Aeration, which involves removing small plugs
of soil, loosens soils and can reduce run-off.
See page 129
(c) McGraw Hill Ryerson 2007
The Effects of Resource Exploitation
•
___________ exploitation = resource use
 Humans depend on resource exploitation for jobs, materials, food, shelter,
and energy.
 ___________ can lead to habitat loss, soil degradation, and contamination of
water supplies.
 Contamination is the introduction of harmful
chemicals or micro-organisms into the environment.
 Many mining and resource exploitations require ___________ efforts.
• Reclamation attempts to reduce environmental impacts of
exploitation to restore the original habitat.
 ___________ ___________ is the extraction of resources until they are gone.
 This can result in extinction, which is the dying out of a species.
 Food webs can be greatly affected over long periods of time
 The overexploited species could be a keystone species.
See pages 130 - 132
(c) McGraw Hill Ryerson 2007
Resource Management and Traditional
Ecological Knowledge
• In Aboriginal cultures, traditional ecological ___________ is passed
down from generation to generation.
 This knowledge reveals what past conditions were like and also how the
ecosystem and humans interact.
 ___________ is found in stories, songs, cultural beliefs, rituals, community
laws, and traditional practices.
 Current ___________ restoration and usage guidelines often involve traditional
knowledge from Aboriginal representatives.
Controlled burning.
 Traditions such as the “spring burn” allow
for ecological renewal.
 Fire suppression, enforced in British
Columbia for over 100 years, has led
to recent issues like the mountain pine
beetle infestation and huge wildfire losses.
See pages 133 - 134
Take the Section 3.2 Quiz
(c) McGraw Hill Ryerson 2007
3.3 How Introduced Species
Affect Ecosystems
• ___________ are plants and animals that naturally inhabit an area.
 Because of the ___________ to North America by many people from other
continents over the past 400 years, many new species have been introduced.
 These new species of plants and animals are called ___________ species,
foreign species, non-native species, exotic species, or alien species.
• Many of these species are harmless or sometimes even beneficial.
 An ___________ species, such as purple loosestrife, negatively affects
native species and often reduces biodiversity as a result.
European
leaf-feeding
beetle, and
the purple
loosestrife.
See pages 138 - 139
(c) McGraw Hill Ryerson 2007
The Impact of Introduced Species
• ___________ species often take advantage of their new habitat.
 They may have no ___________ , are aggressive competitors, and reproduce quickly.
 ___________ : while the native species have an established balance, the invasive
species can throw off this balance.
The sea lamprey
 ___________ : if the invasive species is a predator, it may
have a huge advantage, as the native species may have
no methods to survive.
 Disease and ___________ : by weakening certain species,
a micro-organism invading an ecosystem can drastically
alter the entire ecosystem and the niches within it.
 Habitat ___________ : some invasive species can change
the physical structure of the ecosystem by digging,
burrowing, blocking sunlight, or changing the
chemistry of the ecosystem.
See pages 140 - 141
(c) McGraw Hill Ryerson 2007
Invasive Species in British Columbia
Eurasion Milfoil
Norway rat
See page 142
American Bullfrog
European Starling
(c) McGraw Hill Ryerson 2007
Saving an Ecosystem Under Siege
• It often takes human ___________ to save established ecosystems.
 The Garry Oak Ecosystem Recovery Team (GOERT) is trying to save several
areas of the Garry oak ecosystem in British Columbia.
 95 percent of the original ecosystem has been lost to urban development,
and the remaining 5 percent is threatened by invasive species.
 Garry oak trees are a keystone species.
Garry oak ecosystem
 Scotch broom, English ivy, and other
plant species are its biggest threats.
 GOERT has representatives from many groups
including the British Columbia government,
First Nations, conservationists, scientists, and
businesses.
 Garry oak forests may be better suited to survive in
the future than Douglas fir forests.
See page 143
Take the Section 3.3 Quiz
(c) McGraw Hill Ryerson 2007