Transcript SNC 1D1 unit3humaneffects rev


Human use of ecosystems:

Humans have decreased biodiversity of
ecosystems at a very fast rate

5 factors affecting biodiversity:
 1. Habitat change
 Humans alter a habitat enough that the native
species can no longer live there
 The species either die or move to another
habitat
 We change habitats for agriculture, forestry,
and urban development
 Sometimes habitats are only changed slightly
which forces species to live among houses,
buildings, and small forest areas
 2. Overexploitation
 We use resources faster than they can be
replaced
 Can lead to extinction
 ex. Over fishing has reduced the
number of fish in the world’s ocean
Shark Alert: Species Struggle!
 3. Climate change
 Average temperature, rainfall, and wind
increase or decrease
 Individuals need to adapt to new conditions
in order to survive
 Major cause of loss of biodiversity around the
world
 Global warming is an increase in the earth’s
average temperature
 Mainly caused by carbon dioxide
emissions
Climate Change
 4. Invasive species
 Introduction of non-native species to all parts
of the globe
 This species can cause harm to an ecosystem
because they compete with native species
 They would also have no predators in a new
ecosystem
 Ex. Asian long horn beetle in this area has
damaged trees and caused them to be
removed
Zebra and Quagga Mussels
 5. Pollution
 Any substance added to the environment that
produces a condition that is harmful to
organisms
 ex.
– solid waste that can’t be recycled
- CO2 gas in the air – produced from
cars, air planes, power plants,
and
factories
- fertilizer run-off from farms
- salt run-off from roads

In Canada, pollutants come from mining and
refining metals, electric power generators, oil
and gas operations, and cars
Nitrogen and sulphur are the most common
pollutants in those emissions
 The emissions combine with water vapour in the
air to form acids (this forms acid rain)

 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

Soil Profile:

1. topsoil
 Uppermost layer in soil
 Contains decaying organic
matter, rock particles, bacteria,
fungi, insects, worms

2. subsoil
 Layer below topsoil
 Has roots from trees and
bacteria

3. bedrock
 Bottom of the soil
 Is solid rock and water can’t
pass through it
 Therefore, acid rain would
affect the topsoil and subsoil

Acidity is an abiotic factor that is connected to the
chemical environment of soil


Acids are very common in our life, for example, in
orange juice we drink
pH scale 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 acidic, ex. pH = 2
 Acidic soil can damage plant growth
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.