1. 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 their traits.
A salmon with a smaller tail may never have a chance
to spawn because it cannot swim to the correct location.
A salmon with a large tail may be able to swim faster and farther.
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2. 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.
___________ describes the type of
natural selection where many different species appear from one original species.
Galapagos finches
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3. 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.
___________ succession begins with bare rock such as where glaciers scrape away dirt or a volcano erupts.
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.
Bare rock.
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4. 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.
___________ 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.
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5. 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.
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6. 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 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.
Mountain pine beetle.
See page 117
Take the Section 3.1 Quiz
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7. 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.
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.
Wetlands are vital ecological features in British Columbia.
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8. 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.
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9. 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.
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10. 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.
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11. Habitat Loss (continued)
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12. 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.
Topsoil, the upper layer of soil, is where most
of the nutrients, water, and air are found
for plant growth.
Converting a tropical rainforest into farmland.
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13. 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.
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.
Farm animals, such as these cows, can compact soils.
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14. 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.
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15. 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.
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.
Controlled burning.
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Take the Section 3.2 Quiz
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16. 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.
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17. 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.
___________ : 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.
The sea lamprey
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18. Invasive Species in British Columbia
Eurasion Milfoil
Norway rat
See page 142
American Bullfrog
European Starling
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19. 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.
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.
Garry oak ecosystem
See page 143
Take the Section 3.3 Quiz
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