Transcript Unit 1 Review

1.1 Biomes
• The word “biosphere” refers to anywhere on Earth living things exist.
 A biome is a region with similar biotic and abiotic components.
 Biotic = living things
 Abiotic = non-living things (air, water, soil, etc.)
 A biome here in BC can be the same as a biome in
New Zealand.
 If biotic and abiotic conditions are the same, similar
biomes can exist far apart.
• In this course, eight terrestrial biomes will be studied.
 Biomes are classified based on many qualities, such as water availability,
temperature, and interactions between biotic and abiotic factors.
 Boreal forest, desert, grassland, permanent ice, temperate deciduous forest,
temperate rainforest, tropical rainforest and tundra.
See pages 8 -10
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Factors That Influence the Characteristics and
Distribution of Biomes
• Certain characteristics help to identify biomes.
 Temperature and precipitation are two of the
most important abiotic factors.
 Other factors include latitude, elevation and
ocean currents.
See pages 10 - 13
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Factors That Influence the Characteristics and
Distribution of Biomes (continued)
• Latitude is an abiotic factor that influences biomes.
 Latitude is the distance north and south from the equator.
 Latitude influences both temperature
and precipitation.
 The tropical zone has very warm
temperatures and high precipitation.
• The sun shines straight down
• warm air holds more moisture
than cooler air.
• Elevation also influences biomes.
 Higher elevations have less air, and therefore less heat is retained.
 Windward sides of mountains are wet, leeward sides are very dry.
• Ocean currents carry warmth and moisture to coastal areas.
 Where warm currents meet land, temperate biomes are found.
See pages 14 - 15
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Climatographs
• Climate refers to the average pattern of weather conditions over a
period of several years.
 A climatograph shows the average temperature and precipitation for a location
over a period of 30 years or more.
• Biomes are often defined using information in climatographs.
 Examine the differences between Tofino and Osoyoos
See pages 16 - 17
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Adaptations and Biomes
•
Biomes are often identified with characteristic biotic factors.
 For example, a cactus in the desert, or a caribou on the tundra.
 Many of these characteristic factors have special adaptations for that biome.
 An adaptation is a characteristic that allows an organism to better survive and
reproduce.
1. Structural adaptation - a physical feature that helps an organism survive.
• A wolf has large paws to help it run in snow.
2. Physiological adaptation - a physical or chemical event
inside the body of an organism that allows it to survive.
• A wolf maintains a constant body temperature.
3. Behavioural adaptation - a behaviour that helps an
organism to survive.
• A wolf hunts in packs to capture large prey.
See pages 18 - 19
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A Survey of Biomes:
Tundra and Boreal Forest
See pages 20 - 21
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A Survey of Biomes: Temperate Deciduous
Forest and Temperate Rainforest
See pages 22 - 23
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A Survey of Biomes:
Grassland (Temperate and Tropical)
See pages 24 - 25
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A Survey of Biomes: Tropical Rainforest and
Desert (Hot and Cold)
See pages 26 - 27
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A Survey of Biomes:
Permanent Ice (Polar Ice)
See pages 28
Take the Section 1.1 Quiz
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1.2 Ecosystems
• By studying ecosystems now, and in the past, we can better
understand what may happen in the future.
 Historical ecology is the study of natural and written materials in an attempt to
better understand the ecology of a certain area.
 Many First Nation’s sources are also utilized to better understand nature.
• An ecosystem is made up of many parts.
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Abiotic factors include air, water, soil, nutrients and light.
Biotic factors include plants, animals and micro-organisms.
Ecosystems can take up many hectares of land, or can be the size of an old log.
A habitat is where an organism lives.
The habitat of the red fox often includes the
edges of forests or marshlands
See pages 34 - 36
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Abiotic Interactions in Ecosystems
•
Although they are sometimes overlooked, the abiotic components are what allow
the biotic components to survive in an ecosystem.
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Abiotic factors include oxygen, water, nutrients, light and soil.
 Oxygen is produced by the green plants and certain micro-organisms, and is used
by animals and most other micro-organisms.
 Water is necessary for all life.
 Nutrients often enter the food chain with plants, and are very
important for growth.
 Light is required for photosynthesis,
which is the process in plants that
converts and stores the Sun’s energy
into starches and carbohydrates.
 Soil not only contains water and nutrients,
but also is home to many plants and animals.
See pages 37 - 38
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Biotic Interactions in Ecosystems
• A community of organisms = all the organisms that interact within an ecosystem.
 A population of organisms refers to all of the members of a certain species within an
ecosystem.
 A species refers to all of the organisms within an ecosystem that have the same
structure, and who can reproduce with each other.
• Organisms can have many types of relationships in a population. These
relationships are called symbiotic.
 Commensalism - one species benefits, one is not affected
 For example, the barnacles on a whale
 Mutualism - both species benefit
 For example, a bee gathering nectar from a flower
 Parasitism - one species benefits, the other is harmed
 For example, hookworm living in dogs
See pages 39 - 43
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Niches, Competition and Predation
• A niche refers to the role an organism has within an ecosystem.
 How an organism fits into its environment physically, chemically and
biologically.
• Competition occurs when a resource is
desired by two or more individuals.
 Competition usually means resources are limited
 This limits the size and health of that individual,
and perhaps that population.
• Predation is the relationship between the “eaters” and the “eaten”.
 Predators have adaptations to help them catch their prey.
 Prey have adaptations to help avoid predators.
 Examples include spines and shells, camoflage and mimicry.
 The number of predators and prey influence each other.
See pages 44 - 47
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Biodiversity in Ecosystems
• Biodiversity refers to the the variety and number of different
individuals and species in an ecosystem.
 Healthy ecosystems generally have high biodiversity.
 Most biodiversity losses occur from the loss of habitat.
• Humans often have a negative impact on biodiversity.
 Many efforts are now made to lessen this
impact in order to maintain biodiversity.
 Ecological management programs try to
balance human progress with
maintaining biodiversity.
See page 48
Take the Section 1.2 Quiz
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2.1 Energy Flow in Ecosystems
•
Biomass is the total mass of all living things in a given area.
 Biomass is also sometimes used to the mass of organic materials used to
produce biofuels such as biogas.
 Biomass is generally measured in g/m2 or kg/m2
•
Within an organism’s niche, the organism interacts with the
ecosystem by:
1. Obtaining food from the ecosystem
2. Contributing energy to the ecosystem
 Plants are called “producers” because they produce
carbohydrates from carbon dioxide, water and the sun’s energy.
 “Consumers” get their energy by feeding on producers or other consumers.
 Decomposition is the break-down of wastes and dead organisms, by
organisms called “decomposers”, through the process of biodegradation.
See pages 56 - 59
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Energy Flow and Energy Loss in Ecosystems:
Food Chains
• Scientists use different methods to represent energy moving
through ecosystems.
Examples of terrestrial and aquatic
 Food chains
 Food webs
 Food pyramids
food chains
• Food chains show the flow of
energy in an ecosystem
 Each step is a trophic level
 Feeding & niche relationship
 Producers = 1st trophic level
 Primary consumers = 2nd trophic level
 Secondary consumers = 3rd trophic level
 Tertiary consumers = 4th trophic level
See pages 59 - 60
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Energy Flow and Energy Loss in Ecosystems:
Food Chains (continued)
•
Consumers in a food chain can be classified as:
1. Detrivores - consumers that obtain energy and nutrients from dead organisms
and waste matter
 Includes small insects, earthworms, bacteria and fungi
 Detrivores feed at every trophic level
 Detrivores have their own, separate food chains,
and are very numerous
2. Herbivores - primary consumers
 herbivores eat plants (producers) only
This dung beetle
3. Carnivores - secondary or tertiary consumers
is a detrivore.
 Secondary consumers eat non-producers, such as herbivores
 Tertiary consumers eat secondary consumers
 Aka top consumers, top carnivores or top consumers
4. Omnivores - consumers that eat both plants and animals
See page 61
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 Examples include humans and bears
Energy Flow and Energy Loss in Ecosystems:
Food Webs
• Most organisms are part of many food chains.
 To represent interconnected food chains, scientists create a food web.
 Food webs are models of the feeding relationship in an ecosystem.
 Arrows in a food web represent the flow of energy and nutrients.
 Following the arrows leads to the top carnivore(s).
This food web
represents a
terrestrial
ecosystem that
could be found in
British Columbia.
See page 62
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Energy Flow and Energy Loss in Ecosystems:
Food Pyramids
• Food pyramids show the changes in available energy from one
trophic level to another in a food chain.
 Aka ecological pyramids
 Energy enters at the first tropic level (producers), where there is a large amount
of biomass, and therefore much energy
 It takes large quantities of organisms in one tropic level to meet the energy
needs of the next trophic level.
 Each level loses large amounts of the energy
it gathers through basic processes of living.
 80% - 90% of energy taken in by consumers
is used in chemical reactions in the body,
and is lost as heat energy.
 There is very little energy if left over for
See page 63
growth or increase in biomass.
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Energy Flow and Energy Loss in Ecosystems:
Food Pyramids (continued)
• Food pyramids are also known as ecological pyramids.
 Ecological pyramids may show biomass, population or energy numbers.
 The amount of life an ecosystem can contain is based on the bottom level of
the ecological pyramid, where producers capture energy from the sun.
 Each level in the energy pyramid = a loss of 90% of total energy available
 Lower trophic levels have much
larger populations than upper levels.
 This shows the importance of
maintaining large, biodiverse
populations at the lowest levels
of the food pyramid.
See pages 63 - 64
Take the Section 2.1 Quiz
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2.2 Nutrient Cycles in Ecosystems
•
Nutrients are chemicals required for growth and other life processes.
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Human activities can upset the natural balance of nutrient cycles.
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Nutrients move through the biosphere in nutrient cycles, or exchanges.
Nutrients often accumulate in areas called stores.
Without interference, generally the amount of nutrients flowing into a store equals the amount of
nutrients flowing out.
Land clearing, agriculture, urban expansion, mining, industry and motorized transportation can all
increase the levels of nutrients more quickly than the stores can absorb them.
Excess nutrients in the biosphere can have unexpected consequences.
There are five chemical elements required for life.
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Carbon, hydrogen, oxygen and nitrogen cycle between living things and the atmosphere.
Phosphorous cycles in from sedimentary rock.
See pages 68 - 70
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Nutrient Cycles:
The Carbon Cycle
•
Carbon atoms are a fundamental unit in cells of all living things.
 Carbon is also an essential part of chemical processes that sustain life.
•
Carbon can be stored in many different locations.
 Short-term shortage is found in aquatic and terrestrial organisms,
and in CO2 in the atmosphere and top layers of the ocean.
 Longer-term storage is found in middle and lower ocean layers as dissolved CO2, and in coal,
oil and gas deposits in land and ocean sediments.
•
Sedimentation traps many long-term stores of carbon
 Layers of soil and decomposing organic matter become buried
on land and under the oceans.
 Slowly, under great pressure over many years, coal, oil and gas form.
 Layers of shells also are deposited in sediments on the ocean floor, forming carbonate rocks
like limestone over long periods of time.
•
Carbon stores are also known as carbon sinks
See pages 71 - 72
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Nutrient Cycles:
The Carbon Cycle (continued)
•
Carbon is cycled through ecosystems in a variety of ways.
 Photosynthesis: energy from the sun allows CO2 and H2O to react
 CO2 + H2O + sunlight  C6H12O6 + O2
 Carbon in the atmosphere is transformed by plants into carbohydrates.
 Photosynthesis also occurs in cyanobacteria and algae in oceans.
 Cellular respiration: carbohydrates release energy in consumers
 C6H12O6 + O2  CO2 + H2O + energy
 The energy released is used for growth, repair and other life processes.
 Decomposition: decomposers break down large quantities of cellulose
 Cellulose is a carbohydrate most other organisms cannot break down
 Ocean Processes: CO2 dissolves in cold, northern waters and sinks
 Ocean currents flow to the tropics, the water rises and releases CO2
 This process is called ocean mixing.
 Eruptions and fires - volcanic eruptions can release CO2
 Forest fires also release CO2
See pages 73 - 76
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Nutrient Cycles:
The Carbon Cycle (continued)
See page 76
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Nutrient Cycles:
The Carbon Cycle (continued)
• Many human activities can influence the carbon cycle
 Since the start of the Industrial Revolution (160 years ago), CO2 levels have
increased by 30% from the increased burning of fossil fuels.
 The increase in CO2 levels in the previous 160 000 years was 1% - 3%
 Carbon is being removed from long-term storage more quickly than it
naturally would as we mine coal and drill for oil and gas.
 CO2 is also a greenhouse gas, which traps heat in the atmosphere.
 Clearing land for agriculture and urban development reduces plants that can
absorb and convert CO2.
 Farmed land does not remove as much CO2 as natural vegetation does.
See page 77
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Nutrient Cycles:
The Nitrogen Cycle
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Nitrogen is very important in the structure of DNA and proteins.
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The largest store of nitrogen is in the atmosphere in the
form N2.
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In animals, proteins are vital for muscle function.
In plants, nitrogen is important for growth.
Approximately 78% of the Earth’s atmosphere is N2 gas.
Nitrogen is also stored in oceans, and as organic matter in soil.
Smaller nitrogen stores are found in terrestrial ecosystems and
waterways.
Nitrogen is cycled through processes involving plants
1.
2.
3.
Nitrogen fixation
Nitrification
Uptake
See page 78
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Nutrient Cycles:
The Nitrogen Cycle (continued)
•
Nitrogen fixation is the conversion of N2 gas into compounds
containing nitrate (NO3–) and ammonium (NH4+)
 Both nitrate and ammonium compounds are usable by plants.
 Nitrogen fixation occurs in one of three ways
1. In the atmosphere - lightning provides the energy for N2 gas to react with
O2 gas to form nitrate and ammonium ions.
 Compounds formed by these ions then enter the soil via precipitation
 This only provides a small amount of nitrogen fixation.
2. In the soil - nitrogen-fixing bacteria like Rhizobium in the soil convert N2
gas into ammonium ions
 These bacteria grow on the root nodules of legumes like peas.
 The plants provide sugars, while bacteria provide nitrogen ions.
3. In the water - some species of cyanobacteria also convert N2 into
ammonium during the process of photosynthesis.
See pages 78 - 79
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Nutrient Cycles:
The Nitrogen Cycle (continued)
•
Nitrification occurs when certain soil bacteria convert ammonium.
 Ammonium is converted into nitrates (NO3–) by nitrifying bacteria.
 Ammonium is converted to nitrite (NO2–), which is then converted to nitrate.
•
Nitrates enter plant roots via uptake
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These nitrogen compounds compose plant proteins.
Herbivores then eat plants, and use nitrogen for DNA and protein
synthesis.
Nitrogen is returned to the
atmosphere via denitrification.
 Nitrates are converted back to N2
by denitrifying bacteria.
 N2 is also returned to the
atmosphere through volcanic eruptions.
See page 80
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Nutrient Cycles:
The Nitrogen Cycle (continued)
•
Excess nitrogen dissolves in water, enters the waterways, and
washes into lakes and oceans.
 The nitrogen
compounds
eventually
become trapped in
sedimentary rocks,
and will not be
released again until
the rocks weather.
See page 81
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Nutrient Cycles:
The Nitrogen Cycle (continued)
•
Human activities can also affect the nitrogen cycle.
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Due to human activities, the amount of nitrogen
in the ecosystem has doubled in the last 50 years.
Burning fossil fuels and treating sewage releases
nitrogen oxide (NO) and nitrogen dioxide (NO2).
 Burning also releases nitrogen compounds that increase acid precipitation in the form of
nitric acid (HNO3).
Agricultural practices often use large amounts of nitrogen-containing fertilizers.
 Excess nitrogen is washed away, or leaches, into the waterways.
•
This promotes huge growth in aquatic algae = eutrophication
•
These algal blooms use up all CO2 and O2
and block sunlight, killing many aquatic organisms.
•
The algal blooms can also produce neurotoxins that
poison animals.
See pages 82 - 83
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Nutrient Cycles:
The Phosphorous Cycle
• Phosphorous is essential for life processes in plants and animals.
 Phosphorous is a part of the molecule that carries energy in living cells.
 Phosphorous promotes root growth, stem strength and seed production.
 In animals, phosphorous and calcium are important for strong bones.
• Phosphorous is not stored in the atmosphere.
 Instead, it is trapped in phosphates (PO43–, HPO42–, H2PO4–) found in rocks and
in the sediments on the ocean floor.
• Weathering releases these phosphates from rocks.
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Chemical weathering, via acid precipitation or lichens, releases phosphates.
Physical weathering, where wind, water and freezing release the phosphates.
Phosphates are then absorbed by plants, which are then eaten by animals.
Weathering doesn’t occur until there is geologic uplift,
exposing the rock to chemical and physical weathering.
See pages 83 - 84
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Nutrient Cycles:
The Phosphorous Cycle (continued)
• Humans add excess phosphorous to the environment through
mining for fertilizer components.
 Extra phosphorous, often long with potassium, then enters the ecosystems
faster than methods can replenish the natural stores.
• Humans can also reduce
phosphorous supplies.
 Slash-and-burning of
forests removes
phosphorous from trees,
and it then is deposited as
ash in waterways.
See page 85
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How Changes in Nutrient Cycles
Affect Biodiversity
•
Any significant changes to any of these nutrients
(C, H, O, N or P) can greatly impact biodiversity.
 Carbon cycle changes are add to climate change and global warming.
 Slight temperature fluctuations and changes in
water levels can drastically change ecosystems.
 Changes influence every other organism in those
food webs.
 Increased levels of nitrogen can allow certain plant
species to out-compete other species, decreasing
resources for every species in those food webs.
 Decreased levels of phosphorous can inhibit the
growth of algal species which re very important
producers in many food chains.
See pages 86 - 87
Take the Section 2.2 Quiz
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2.3 Effect of Bioaccumulation
on Ecosystems
• Amphibians (like frogs) live on both land and in the water.
 They are also sensitive to chemicals changes in the environment.
 They are therefore valuable indicators of environmental health.
 Since the 1980s, much of the world’s amphibian species have suffered
declines in population.
 There has also been alarming increases in amphibian birth deformities
in that time.
 Many theories attempt to explain these changes, including drought,
increased UV rays, pollution, habitat loss, parasites and diseases.
Amphibians, like this frog, have
exhibited drastic changes since
the 1980s.
See pages 92 - 93
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Bioaccumulation
• Bioaccumulation refers to an organism slowly building
up the amount of chemicals in their bodies.
 Many harmful chemicals cannot be decomposed naturally.
 These chemicals can be eaten or absorbed, and sometimes
cannot be removed from the body of the organism effectively.
 If a keystone species suffers a chemical bioaccumulation,
it can affect every other organism in its far reaching niches.
 A keystone species is a vital part of an ecosystem.
• Biomagnification refers to the animals at the top of the food pyramid
receiving huge doses of accumulated chemicals.
 At each level of the food pyramid, chemicals that do not get broken down build up
in organisms.
 When the consumer in the next trophic level eats organisms with a chemical
accumulation, they receive a huge dose of the chemical(s).
See page 94
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Bioaccumulation (continued)
• An example of bioaccumulation in BC is the effect of PCBs on the
Orca.
 PCBs are a chemical that were used for many industrial and electrical
applications in the mid 20th century.
 PCBs were banned in 1977 because of fears of their environmental impact.
 PCBs bioaccumulate, and
also have a long-half life
(they break down very slowly).
 PCBs will affect the
reproductive cycles of Orcas
until at least 2030.
The bioaccumulation of PCBs begins with the absorption of
the chemicals by microscopic plants and algae.
See page 95
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Bioaccumulation (continued)
• Chemicals like PCBs and DDT are called
persistent organic pollutants (POPs)
 POPs contain carbon, like all organic compounds, and remain in water and
soil for many years.
 Many POPs are insecticides, used to control pest populations.
 DDT was introduced in 1941 to control mosquito populations, and is still
used in some places in the world.
 Like PCBs, DDT also bioaccumulates
and has a long half life.
 At even low levels (5 ppm), DDT in
animals can cause nervous, immune
and reproductive system disorders.
• ppm = parts per million
Spraying DDT, 1958
See page 96
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Bioaccumulation (continued)
• Heavy metals also bioaccumulate.
 Lead, mercury and cadmium of the most polluting heavy metals.
 Lead is found naturally at low levels, but levels have increased.
 Lead is not considered safe at any level.
 Many electronics contain lead, and must
be recycled carefully.
 Lead can cause anemia, nervous and
reproductive system damage.
 Cadmium is also found in low levels naturally.
 Cadmium is used in the manufacture of plastics
and nickel-cadmium batteries.
 It is toxic to earthworms, and causes many health problems in fish.
 In humans, the main source of cadmium exposure is cigarette smoke.
• Cadmium causes lung diseases, cancer,
nervous and immune system damage.
See page 97
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Bioaccumulation (continued)
 Mercury also is found naturally.
 Much more has entered ecosystems through the burning of fossil fuels, waste
incineration, mining and the manufacture of items like batteries.
 Coal burning adds 40% of of the mercury released into the atmosphere.
 Mercury bioaccumulates in the brain, heart and kidneys of many animals.
 Fish bioaccumulate mercury compounds, adding risk for any organisms
eating fish.
• Reducing the effects of chemical pollution
 By trapping chemicals in the soil, they cannot enter the food chains as easily.
 Bioremediation is also used, as micro-organisms or plants are used to help
clean up, and are then removed from the ecosystem.
 The oil industry will often use bacteria to “eat” oil spills.
 Certain natural species are also excellent at bioremediation.
See pages 98 - 99
Take the Section 2.3 Quiz
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Jeremy Piven – Bioaccumulation of Mercury
Piven had complained of exhaustion and been eating some type of fish twice daily. His
physician, Dr. Colker said that Piven's condition, left untreated, could result in heart problems,
cognitive problems, renal failure and, in very extreme cases, death.
Read more: http://www.digitaljournal.com/article/263686#ixzz1ELAImEzD
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3.1 How Changes Occur Naturally
in Ecosystems
• When an organism is born, it belongs to a species,
but it also is born with unique characteristics.
 Like humans with different coloured eyes and different heights.
 Sometimes, these unique characteristics give that individual an advantage
within their niche. ie, a salmon with a slightly larger tail may be able to swim a
little faster or a little farther in a river.
• Natural selection is the process where
individuals with advantages are better able
to reproduce and pass along their traits.
 Those with unfavourable 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 can’t swim to the correct location.
See pages 108 - 109
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How Organisms Adapt to Change
• The Galapagos Islands, off the coast of Ecuador, are perhaps the
most famous example of natural selection.
 Many species on these islands are very similar to each other,
and also to species on the South American continent.
 There are thirteen species of finch on the islands.
 Each is descended from a finch species from the mainland.
 Each species has very unique characteristics that allows
them to thrive in their own niche, and not compete with
other finches for resources.
Galapagos
finches
• Adaptive radiation is the term for this type of
natural selection.
 Many different species appear from one original species.
See page 110
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Adaptive radiation
• Darwin’s finches on the left.
• Ancestors of an ancient dinosaur on the right.
(c) McGraw Hill Ryerson 2007
How Ecosystems Change Over Time:
Primary Succession
•
Ecological succession refers to the changes in the biotic characteristics in an area
over time.
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Over time, the life in an area changes
There are two types of ecological succession:
primary succession and secondary succession.
Primary succession - begins with nothing but bare rock
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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, animals begin to appear.
Primary succession occurs in this way 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, albeit more slowly.
2. Secondary succession - 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.
 There is already soil, seeds and insects, so it
only lasts decades.
See page 114
(c) McGraw Hill Ryerson 2007
How Natural Events Affect Ecosystems
• Many other disturbances can affect mature communities.
• Flooding
 Water is not contained within natural or artificial barriers.
 Generally occurs in locations where water levels can change rapidly.
 It 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, floods coastal areas.
• Drought
 Occurs when an area receives a lower than average amount of rainfall over a
very 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)
• Insect 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 even 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.
See page 117
Take the Section 3.1 Quiz
(c) McGraw Hill Ryerson 2007
3.2 How Humans Influence Ecosystems
• Wetlands are special 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 the Earth.
 Because they hold large amounts of water, they can help prevent flooding.
• Human encroachment has caused many
BC wetlands to disappear.
 In the past 100 years:
 Up to 70% of the wetlands in the lower
Fraser Valley have been lost.
 Up to 85% of the wetlands in the South
Okanagan have been lost.
Wetlands are vital ecological
features in British Columbia.
See pages 122 - 123
(c) McGraw Hill Ryerson 2007
Understanding Sustainability
• “Sustainability” is a word that is used often, and can be defined in
more than one way:
 “The ability for an ecosystem to sustain ecological processes”.
 These processes enable biodiversity and keep the ecosystem healthy.
 “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
• “Land use” refers to how humans use land around us for urban
development, agriculture, industry, mining and forestry.
 All of the land around us, even in cities, was once a part of an ecosystem.
• “Resource 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 sulphur are very important
to BC’s current economy.
See page 126
(c) McGraw Hill Ryerson 2007
Habitat Loss
• The use of land and resources have seen humans encroach on
natural ecosystems very aggressively in the past 150 years.
 As a result of this expansion, habitats have been lost or fragmented.
 “Habitat loss” refers to to loss of habitats due to human activities.
 “Habitat 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
• 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 = monoculture
 This reduces biodiversity, and leaves the crop vulnerable to pests or disease.
 Polycultures, of many plant species, are more economically and biologically
diverse.
 Deforestation is still occurring in many tropical rainforests.
 Deforestation results in soil degradation.
 Soil degradation is 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.
See page 128
(c) McGraw Hill Ryerson 2007
The Effects of Agriculture
• If fields are left exposed during non-planting seasons,
water and wind erosion can occur.
• In areas like southwestern BC, the soil can become compacted.
 Soil particles are squeezed together and become compacted.
 This is 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.
Farm animals, such as these
cows, can compact soils.
 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
•
Resource exploitation = resource use



Humans depend on resource exploitation for jobs,
materials, food, shelter and energy.
Exploitation 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 reclamation efforts.
• Reclamation attempts to reduce environmental impacts of exploitation, and
tries to restore the original (or at least functional) habitats.
Overexploitation is the extraction of resources until they are gone.
 This can result in extinction, such as with the passenger pigeon.
 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 knowledge is passed
down from generation to generation.
 This knowledge reveals what past condition were like, and also how the
ecosystem and humans interact.
 Knowledge is found in stories, songs, cultural beliefs, rituals, community laws
and traditional practices.
 Current ecological restoration and usage guidelines often involve this
traditional knowledge from Aboriginal representatives.
 Traditions such as the “Spring burn” allow
for ecological renewal.
 Fire suppression, enforced in BC 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
Understanding Sustainability
• “Sustainability” is a word that is used often, and can be defined in
more than one way:
 “The ability for an ecosystem to sustain ecological processes”.
 These processes enable biodiversity and keep the ecosystem healthy.
 “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.
Who is this player?
See pages 8 - 9
Take the Section 8.1 Quiz
(c) McGraw Hill Ryerson 2007
Understanding Sustainability
• “Sustainability” is a word that is used often, and can be defined in
more than one way:
 “The ability for an ecosystem to sustain ecological processes”.
 These processes enable biodiversity and keep the ecosystem healthy.
 “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.
Who is this player?
See pages 8 - 9
Take the Section 8.1 Quiz
(c) McGraw Hill Ryerson 2007
3.3 How Introduced Species
Affect Ecosystems
• Native species are plants and animals that naturally inhabit an area.
 Because of the immigration to North America by many people from other
continents over the past 400 years, many new species have been introduced
accidentally (and on purpose) here.
 These new species of plants and animals are called introduced species
• Aka foreign species, non-native species, exotic species or alien species.
• Many of these species are harmless, or sometimes even beneficial.
 An invasive species, such as Purple Loosestrife, negatively impacts native
species, and often reduces biodiversity as a result.
The
European
leaf-feeding
beetle (left),
and the
Purple
Loosestrife.
See pages 138 - 139
(c) McGraw Hill Ryerson 2007
The Impact of Introduced Species
• Invasive species often take advantage of their new habitat.
 They may have no predators, are aggressive competitors, and reproduce fast.
 Competition: while the native species have an established balance, the
invasive species can throw off this balance.
 Predation: if the invasive species is a predator, it may
The sea lamprey
have a huge advantage, as the native species may have
no methods to survive.
 Disease and Parasitism: by weakening certain species,
a micro-organism invading an ecosystem can drastically
alter the entire ecosystem and the niches within it.
 Habitat Alteration: 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
See page 142
(c) McGraw Hill Ryerson 2007
Saving an Ecosystem Under Siege
• It often takes human intervention to save established ecosystems.
 The Garry Oak Ecosystem Recovery Team (GOERT) is trying to save several
areas of the Garry Oak ecosystem in BC.
 95% of the original ecosystem has been lost to urban development, and the
remaining 5% 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.
 The BC government, First Nations, conservationists,
scientists and businesses believe this work is critical.
 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