Download SNC1D Ecology Lesson 6

Threats to Biodiversity
Habitat Loss
• Deforestation: trees cut and never replanted
(for timber or agriculture reasons)
• Tropical forests only cover 7% of Earth’s land
yet contain over half of Earth’s species.
• Wetland drainage:6% of the earths surface,
24% of all wetlands are in Canada (Manitoba
and Ontario)
• Habitat loss and species loss are one
problem but also plants in wetlands help filter
out sediment and pollutants from the water
helping to keep it clean.
Alien Species
• Introducing new (non-native) species
from a different area into an ecosystem.
May be purposeful or an accident
through shipments of goods by humans
• Most alien species are harmless or
even beneficial in their new ecosystem
Invasive Species
• An alien species that takes over the habitat of
native species
• Upset equilibrium (balance) of the ecosystem
• Many aquatic invasive species are
transported in the ballast water of a ship
(helps to keep the boat in balance) Ballast
water is like a huge aquarium containing fish,
and microscopic organisms
• ZEBRA MUSSELS AND LAKE ERIE
• GOBIE and the GREAT LAKES
Over Exploitation
• Taking too much of a
resource for human use to
the point of resource
depletion
• The cod fishery on the
East coast is an example
of this
Ecosystem connectivity
• Several ecosystems are connected through
the lifecycle of some of it’s organisms.
• Ex. Salmon: they hatch in fresh water stream
temperate rain forest (B.C.)
• Spend adult life in Pacific ocean picking up
and storing nutrients
• Return to birth place to spawn (breed)
• Bears catch salmon bring into the forest and
the nutrients from the ocean are released into
the forest as its body decays.
Extinction
• Death rate remains higher than birth rate for
a long time= species will go extinct
• Not necessarily only caused by humans,
ecosystems change and species can go
extinct because of this
• Patterns of natural extinction:
– Background extinction-slow change in ecosystems
result in recurring extinction
– Mass extinction: sudden change in ecosystems on
earth result in many species going extinct all at
once.
Extinction
Current extinction rates
• Due to human presence rate is 100 to 1000x
higher than normal background rates.
• This problem has been called the
BIODIVERSITY CRISIS
• Resulted by humans and acts such as
deforestation, habitat destruction and air and
water pollution changing abiotic and biotic
factors
Restoring ecology
• The renewal of degraded or destroyed ecosystems ( like
the TED talks video)
• Reforestation methods:
– Seeding efforts and management have shown this
works
• Wetland restoration:
– Alfred bog is an example Pg. 87
– Water control is used to restore water to drained
wetlands then replanting native species occurs
• Controlling alien species:
– Biocontrol: the use of a species to control the
population growth or spread of an undesirable species
– Problems go with this-sometimes the species it
controls can affect native species negatively.
– Gypsy moth and Parasitoid fly example
Controlling alien species
• Chemicals: poisons directly presented to the
organisms to be controlled can have fairly contained
results (e.g. killing rats on an island had big impacts
on the rats population and minimal on the bird
population of the island)
• Bioremediation: the use of living organisms to clean
up contaminated areas naturally
• E.g. fungi, plants and bacteria can be used to extract
contamination.
• Bioaugmentation: the use of organism to add
essential nutrients to depleted soils
• E.g. clover planted to restore nitrogen levels naturally
•
The future of Restoration
Ecology
• Alberta Tar
sands result
in almost
complete
habitat and
ecosystem
destruction
• The oil spill
off the coast
of New
Mexico