SNC1D1
Human Effects on Ecosystems
Humans and Biodiversity:
o Humans use of ecosystems:
 Humans have decreased biodiversity of ecosystems at a very fast rate
Factors Affecting Biodiversity:
o 5 factors affecting _________________________:
1. Habitat Change
o Humans alter a habitat enough that the ______________ _________________ can no longer live
there
o The species either ___________ or _____________ to another habitat
o We change habitats for ___________________, ______________________, and
_______________________________________
o Sometimes habitats are only changed slightly which forces species to live among houses, buildings,
and small forest areas
2. Overexploitation
o We use ___________________ faster than they can be replaced
 Can lead to _________________________
ex. _____________________ has reduced the number of fish in the world’s ocean
3. Climate Change
o Average ___________________, _____________________, and ______________ increase or
decrease
o Individuals need to ________________ to new conditions in order to survive
o Major cause of loss of biodiversity around the world
o ____________________________ is an increase in the earth’s average temperature
 Mainly caused by _________________________ emissions
4. Invasive Species
o Introduction of __________________ species to all parts of the globe
o This species can cause harm to an ecosystem because they _______________ with native
species
 They would also have no ____________________ in a new ecosystem
ex. Asian long horn beetle in this area has damaged trees and caused them to be
removed
5. Pollution
o Any ______________________ added to the environment that produces a condition that is
__________________ to organisms
ex. – solid waste that can’t be recycled
- CO2 gas in the air – produced from cars, airplanes, power plants, and
factories
- fertilizer run-off from farms
- salt run-off from roads
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Impact of Pollution on Ecosystems:
o In Canada, ___________________ come from mining and refining metals, electric power
generators, oil and gas operations, and cars
 __________________ and ________________ are the most common pollutants in those
emissions
 The emissions combine with ________________________ in the air to form acids
 This forms __________________________
-Affects soil, vegetation, lakes, rivers, and terrestrial and aquatic
animals
-Acid rain can damage the waxy coating that protects leaves and it can
seep into the soil and burn the skin of earthworms
Assessing Effects on Soil:
o
To assess the condition of soil, it is helpful to know what soil is
o
Soil: a loose covering on the ground containing a mixture of organic matter, minerals, and
moisture
Soil Profile:
Soil
Location
Layer
Topsoil
Uppermost
layer
Subsoil
Below
topsoil
Bedrock
Bottom of
soil profile
Description
Picture
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The pH scale:
o
Acidity is an ______________ factor that is connected to the chemical environment of soil

Acids are very common in our life, for example, in orange juice we drink

________________________ is a measurement of the acidity of substances
ex.
-sour taste in lemons
-water is said to be neutral, pH = 7

Low pH means substance is very ________________, ex. pH = 2
-Acidic soil can damage ______________________________
Definitions:
- overexploitation
- invasive species
- bedrock
- climate change
-pH scale
- basic/alkaline
-soil erosion
-soil
-acidic
-topsoil
-acid rain
-subsoil
-neutral
Homework:
1. Suppose a non-native species of beetle is introduced into a forest. How would you know if the
beetle was becoming an invasive species?
2. Rhinoceros horns are valued in certain countries and are used to make dagger handles. This has
led to the illegal hunting of rhinoceros in all parts of Africa. Rhino populations are low and still
declining.
a. What is the factor that is affecting the rhino population?
b. What is a possibility if the current trend is not reversed?
3. Identify the misconception in each of the following statements. Rewrite each sentence so that it
is no longer misleading.
a. Not all species are important, so some have to be sacrificed.
b. If an ecosystem appears to have a lot of one particular species, then it must be healthy.
c. Biodiversity is unimportant to humans.
4. Easter Island represents an unsustainable use of ecosystem. You have learned that 5 factors can
affect the sustainability of ecosystems. Did all of these factors contribute to the islanders’
demise? Justify your answer.
5. Explain why topsoil is a vitally important layer of soil.
6. Suppose that there has been a sudden growth of algae in a lake in cottage country.
a. Suggest 3 possible causes for this situation.
b. Explain what could happen in the lake.
7. Acid rain is not just a Canadian problem; it is an international problem. Justify this statement.
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