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CHAPTER 3 ANSWERS
Reading Check Answers, p. 111
1. Natural selection occurs when members of a species have certain characteristics that give them an advantage over other
members of that species. These individuals then may pass these favourable characteristics on to their offspring.
2. Adaptive radiation describes the change from a common ancestor into a number of different species that radiate out to
inhabit different niches.
3. An example of adaptive radiation is the cichlid fish where 300 species developed from 1 species, or the 13 species of
Darwin’s finches that developed from 1 species.
Reading Check Answers, p. 115
1. Ecological succession describes the changes that take place over time in the types of organisms that live in an area.
2. In primary succession, soil begins to form from bare rock and lichens.
3. A mature community or climax community is the result of primary succession. A boreal forest or tropical rainforest is an
example of a mature community.
4. Secondary succession occurs as a result of a disturbance to an area, such as by a fire. Since soil and nutrients already
exist, it occurs much faster than primary succession as organisms move back into the disturbed area.
CYU 3.1 p. 121
1. The development of the two sticklebacks in the same lake was caused by competition for food and space.
2. The role of pioneer species, such as mosses and lichens, is to change the biotic and abiotic environment, which will then
allow other species to survive in the ecosystem.
3. Lichens are considered a pioneer species because lichens are able to obtain nutrients from rock through chemical
weathering. Also, lichens decay, adding to the developing soil.
4. New soil is created in primary succession by the release of nutrients from rock through chemical weathering and the
decay of pioneer species plant material, which adds more nutrients to the developing soil.
5. The order is (d), (b), (a), and (c).
6. After a volcanic eruption, all the life and previous soil will be destroyed. Since the cooled lava flow will be barren, this is
primary succession.
7. (a) Lodgepole pine trees naturally defend themselves against the beetle by secreting a resin, which traps and flushes the
adult beetles from the tree.
(b) The mountain pine beetle has had such a devastating impact on lodgepole pine forests because cold temperatures are
not being sustained long enough to kill the beetle larvae and suppression of forest fires has retained large number of older
host trees for the beetles. Older trees do not secrete as much resin to defend against the beetle.
8. There are more types of species in a forest undergoing succession because there is less light available in a mature forest
so there is less of a variety of plant species and therefore fewer different habitats for animals.
9. Darwin’s finches illustrate adaptive radiation since changes in some finches allowed them to adapt to particular niches
and food sources. The individuals that were best adapted survived and reproduced and that is natural selection.
10. Sample answer: bare rock mosses and lichens nutrients available decay more soil new species of plants
established  animals move in abiotic and biotic conditions continue to change mature community
11. (a) There is no soil available in primary succession initially, but there is soil available in secondary succession.
(b) There are no nutrients available initially in primary succession, but there are existing nutrients in secondary succession.
(c) Secondary succession may take decades. Primary succession takes centuries.
13. The scenario should show a progression from grass to small trees and bushes to a forest.
14. Flooding affects ecosystems, causing soil erosion and pollution. Harmful bacteria may be carried in flood water and
cause disease. Prolonged drought destroys habitats, killing animals and plants. Insect infestations can destroy forests and
the habitats for animals.
Reading Check Answers, p. 127
1. Sustainability is the ability of an ecosystem to sustain ecological processes and also the ability to use resources of an
ecosystem without reducing the health or function of the ecosystem.
2. Land use refers to ways we use the land for urban development, agriculture, industry, mining, and forestry.
3. Three types of resource use are urban development, agriculture, and mining.
4. Habitat loss and habitat fragmentation threaten biodiversity because, when habitats are destroyed or fragmented, plant
pollination, seed dispersal, wildlife movement, and plant and animal reproduction are affected.
5. An example of a sustainable practice is selective logging instead of clear-cut logging.
Reading Check Answers, p. 130
1. Deforestation is the practice in which forests are logged or cleared for human use and not replanted.
2. Soil degradation occurs when water and wind erosion remove topsoil from bare land.
3. Two effects of agricultural practices on soil are soil compaction, when soil particles are squeezed together, reducing air
spaces between the particles; and run-off, which adds additional nitrogen, phosphate, and pesticides to the environment.
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4. Aeration improves soil by creating air spaces which improves air and water movement through soil. Small plugs of soil are
removed to create the spaces.
CYU 3.2 p.137
1. Human activities affect wetland ecosystems when wetlands are transformed into parking lots, subdivisions, garbage
dumps, agricultural land, and shopping malls. In addition, pollution from agriculture and industry and the introductions of
invasive species have also degraded these ecosystems.
2. A sustainable ecosystem provides economic opportunities while maintaining biodiversity and ecosystem health.
3. Habitat fragmentation harms ecosystems as plant pollination, seed dispersal, wildlife movement, and plant and animal
reproduction are affected.
4. Deforestation results in soil degradation because the loss of plant life causes water and wind erosion, which removes
topsoil from bare land.
5. The loss of topsoil affects an ecosystem because plants require adequate amounts of topsoil to grow and anchor in, and
when topsoil erodes, the nutrients are lost with the topsoil.
6. (a) Water contamination is the introduction of chemicals, toxins, waste, or microorganisms into the environment in
concentrations that are harmful to living things.
(b) Mining causes water contamination when chemicals, such as cyanide used in gold and silver mining, enter streams and
rivers.
7. Two ways plants can be used in mine reclamation are to absorb contaminants through their root systems and to stabilize
the soil to prevent the contamination from leaching into the water.
8. Overexploitation can lead to extinction when a population becomes so reduced that the genetic diversity is lost. With the
loss of genetic diversity, populations are less resistant to disease and less able to adapt to changes in their environment.
9. Controlled burning practices positively affect ecosystems because this practice recycles nutrients and increases growth of
plants, which attracts wildlife. It also reduces forest litter and opens the forest canopy for plants that require more sunlight. If
forest litter is reduced, forest fires will be less intense.
10. One sustainable practice that can reduce the negative effects of urban expansion is adopting development plans that
incorporate waste treatment, storm water collection, and mixed residential and business building use.
11. (a) The collapse of the cod fishery was due to overexploitation.
(b) Populations in ecosystems are affected by overexploitation as numbers and genetic diversity are reduced.
12. (a) The sustainable practice shown in the photograph is using plants for land reclamation after a mine closure.
(b) In 10 years, the area may be restored to a forest and attract a variety of wildlife.
13. Overexploitation can affect many interactions in a food web as the numbers of predators of the organism will decrease
and the number of prey of the overexploited organism will increase. This can further affect other organisms connected in the
food web.
14. Traditional ecological knowledge can affect the biodiversity of an ecosystem as seen in spring burning of prairie
grasslands by Cree. Controlled burning renewed grassland ecosystems, recycling nutrients and increasing plant growth,
which attracted small mammals to the area. Carnivores, such as coyotes, were attracted by the increase in prey
populations.
Reading Check Answers, p. 143
1. A native species is a plant or animal that naturally inhabits an area.
2. An introduced species is an organism that is transported into a region where it did not exist previously.
3. An invasive species is an organism that can take over the habitat of native species or invade their bodies, which weakens
their immune system.
4. Four ways introduced species can affect ecosystems are: (i) outcompeting native species for resources (for example,
burweed); (ii) predation where native organisms do not have adaptations to escape the introduced predator (for example,
crazy ants); (iii) disease and parasites which weaken the organism’s immune system (for example, lamprey); and (iv) habitat
alteration where the invasive species changes the natural habitat and makes it unsuitable for native species (for example,
wild boar).
Reading Check Answers, p. 144
1. The major threat to the Garry oak ecosystem today is from introduced invasive species.
2. Scotch broom harms the Garry oak ecosystem by reproducing in large numbers and outcompeting native shrubs, ruining
the habitat for native birds and butterflies. It also fixes nitrogen, creating a nitrogen overload, which interferes with the
growth of native species.
3. Two at-risk species in the Garry oak ecosystem are red squirrels and oak trees.
CYU 3.3 p. 147
1. (a) Sample answer: An example of a native species is whitebark pine in the Rocky Mountains or Garry oak in Vancouver
Island ecosystems.
(b) Sample answer: An example of an invasive species is purple loosestrife or Scotch broom.
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2. Some introduced species are a threat to native species because introduced species can take over the habitat or invade
the bodies of native species.
3. The threat of introduced species has increased in the last few decades because of climate change and an increase in
international trade and travel.
4. Three characteristics common to many introduced species are high reproduction rates, aggressive competition, and a
lack of natural predators in their new habitat.
5. Any three of: predation, disease, habitat alteration, and habitat alteration
6. Introduced predator species can be more dangerous than native predators because the prey may not have adaptations to
escape or fight them.
7. Introduced species can alter habitats by making the natural habitat unsuitable for native species by changing abiotic
components such as light levels, influencing the amount of dissolved oxygen in water or nutrients in the soil, and increasing
soil erosion.
8.
Introduced Invasive Species
Method of Introduction into
Negative Effect on Ecosystem
Ecosystem
Eurasian milfoil
Spread by boats as it can grow
Forms dense mats on lake surfaces, cutting off
from fragments
sunlight to organisms
Norway rat
Trading ships
Extremely well adapted and can feed on any food
source; has caused a decline in nesting sea birds
by eating eggs and young
American bullfrog
Imported for restaurant use then
Reproduces rapidly and eats native frogs; will
released into wild
attack ducks and small mammals
European starling
Purposely brought to North
Outcompetes native birds for nesting sites;
America from Europe
causes decline of many bird species
9. (a) Three introduced species in the Garry oak ecosystem are grey squirrels, gypsy moths, and Scotch broom.
(b) The effect of grey squirrels on the Garry oak ecosystem is a decline in the native red squirrel population. The gypsy moth
larvae strip the bark off oak trees and make them more vulnerable to disease. Loss of bark leads to the death of the tree.
Scotch broom has replaced native shrubs and reduced native bird habitats.
10.
(a) Burweed, Scotch broom, European starling
(b) Crazy ants, Norway rat, American bullfrog
(c) Viruses, bacteria, blister rust
(d) Wild boars, Eurasian milfoil
11. Introduced parasites affect ecosystems by weakening the immune system of organisms, allowing stronger species to
outcompete the diseased organism for space or food.
12. Crazy ants will devour all plants and prey on young reptiles, birds, and mammals. They kill red crabs, a keystone
species that is important in reducing leaf litter and recycling nutrients.
13. Blister rust indirectly affects squirrels and nutcrackers in the whitebark pine ecosystem because the loss of the whitebark
pine means the loss of seeds that are eaten by squirrels and nutcrackers.
14. Scientists think that, if the Garry oak ecosystem survives, it may replace the Douglas fir forest in the future because
Garry oak is better adapted to summer droughts than Douglas fir, which warmer temperatures may force farther north and
into alpine regions.
Chapter 3 Review p.148
1. The process that makes change possible in living things is natural selection. When members of a species have certain
characteristics that give them an advantage over other members of the species, the individuals may pass these favourable
characteristics on to their offspring.
2. From one species of stickleback arose several species that were adapted to different niches.
3. Changes in the abiotic parts of an ecosystem, which occur in ecological succession include an increase in the availability
of nutrients, soil, and light.
4. Micro-organisms aid in decomposition and recycle nutrients back to the soil.
5. Pioneer species change the biotic and abiotic environment by decaying waste and creating more soil. They provide food
for insects and other organisms, which attract animals into the community.
6. Mature communities include tundra and temperate rainforests. Sand dunes and wetlands have more rapid changes
occurring.
7. Sample answer: Flooding can result in soil erosion and soil pollution if toxic chemicals are present in flood waters.
8. Three effects of prolonged drought include the destruction of habitats when water becomes scarce, plants and animal
deaths, crop failures, and livestock deaths.
9. The importance of sustainability is that resources will be available for future generations while the functions and health of
the ecosystem are maintained.
10. Examples of sustainable practices described in this chapter include redeveloping industrial areas, streambed restoration
after logging, grassland management, mine reclamation, controlled burning, and plant bioremediation.
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11. Human activities cause habitat fragmentation when roads are constructed through a habitat and the ecosystem is
divided into smaller pieces.
12. Examples of resource exploitation are harvesting fish, timber, mining, and extracting fossil fuels.
13. Water contamination can result from resource exploitation when untreated chemicals and other wastes leach into water
supplies.
14. Students’ answers will vary but could include competitors such as burweed, Scotch broom, European starling; predators
such as crazy ants, Norway rat, and American bullfrog; diseases and parasites such as viruses, bacteria, and blister rust;
and habitat alterations such as those caused by wild boars and Eurasian milfoil.
15. Two examples of populations of keystone species that have been negatively affected by invasive species are the Garry
oak by the gypsy moth and the whitebark pine by a fungus called blister rust.
16. As some food sources became limited, finches with particular beak characteristics were better suited for the
environment and were able to use other food sources. They were able to mate and pass on these favourable beak
characteristics to the next generation. This is natural selection.
17. A living organism becomes extinct when the biotic or abiotic conditions change so much that the organism can no longer
survive and reproduce. Causes of extinction include habitat loss, the introduction of invasive species, and overexploitation.
18. The two main causes of soil degradation are water and wind erosion of soil from the effects of agricultural practices as
well as deforestation.
19. (a) The importance of land use includes the ways we use the land to meet our needs such as urban development,
agriculture, and industry. Resource use is how we obtain and use these materials.
(b) Land use and resource use have greatly increased to meet the need of the growing human population.
20. A soil management practice that improves plant growth is aeration, in which plugs removed from the soil allow water and
air to enter the roots better.
21. Sample answer: Overexploitation affects a food web because it will reduce the number of predators and increase the
number of prey, which will upset the balance of the whole food web.
22. Traditional ecological knowledge can be applied to resource management as controlled burning renews grassland
ecosystems and reduces forest litter, which decreases the intensity of forest fires. Traditional ecological knowledge can be
applied to biodiversity conservation as burning recycles nutrients and increases plant growth. More animals are attracted to
the area, and an increased variety of plants is able to grow.
23. Factors that have caused an increase in invasive introduced species and losses in global biodiversity are climate
change and increased trade and transportation globally.
24. (a) The introduction of an invasive plant species might alter a habitat for other plants as the plants may change the light
levels available to neighbouring plants, decrease oxygen content in the water, change the soil chemistry, or increase soil
erosion.
(b) The introduction of an invasive plant species might alter a habitat for animals when the pollinators change in the
ecosystem, which affects the predators of the pollinators and could change the food web.
25. (a) The white sturgeon may become extinct if the young are unable to reproduce or do not survive until adulthood.
(b) Possible human-caused changes could be overexploitation of sturgeon or their prey; loss of habitat because of pollutants
in the water, which destroys the sturgeon’s prey; increased water temperatures with climate change, which affects fry;
muddy water from soil erosion, which affects the development of the young; and the introduction of invasive species.
(c) Sustainable practices would include restricting the catching of sturgeon until their number substantially increases and
protecting the spawning grounds of the sturgeon. Also, determine which factors led to their decline. If particular introduced
species have helped cause their decline, then create laws to prevent the spread of these species.
Answers Ws 3.1 How Changes Occur Naturally in Ecosystems p. 106
1. What is the cause of the “ yellow dragon”? overgrazing, deforestation, and drought
2. In natural selection, what happens to the best-adapted members of a species?
They will survive and reproduce
3. Why are different species of sticklebacks in British Columbia able to share their habitats?
They have different diets and
reproduce only with members of their own species
4. DYK. Why did the stickleback pairs in Hadley lake disappear? Human s introduced catfish into the lake which became a major
predator and ate them all.
5. Define adaptive radiation.
The change from a common ancestor into a number of different species that “radiate out” to
inhabit different niches.
6. How is it possible that many species of finches came to live on the Galapagos Islands? Different finches evolved different
beaks and were able to eat different kinds of seeds and other food.
7. How is it possible that over 200 species of cichlids evolved from one? Fg 3.4 different cichlids were able to eat different
kinds of food and therefore occupied different niches
8. Define ecological succession.
The changes that take place over time in the types of organisms that live in an area
9. Define primary succession.
Change that occurs in an area where no soil exists such as on bare rock
10. What is a lichen? A symbiotic, mutualistic relationship between a fungus and an algae.
11. List 5 ways that soil is formed from bare rock.
Weathering cause by lichens, wind, rain, freezing and the decomposition
of lichens
12. How long does it take for soil to form?
Hundreds of years
13. Define pioneer species. Lichens and other plants that are the first organisms to survive and reproduce in a area.
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14.
15.
16.
17.
18.
19.
20.
21.
What are the pioneer species in fg 3.7?
lichens and ferns
What is the most important phase in step 1 of fg 3.8? lichens releasing chemicals that stares to break down rock
The 2nd step?
Plants star to die and decay adding more nutrients to the soil
3rd step?
Soil holds more water due to the build up of decomposing materials.
4th step?
Trees begin to grow allowing shade tolerant plants to live under the leaves. Diversity increases greatly
5h step?
A mature community develops that will remain relatively unchanged for years
List 4 examples of climax communities.
Boreal forests, tropical rainforests, grasslands, and deserts
What is the main cause of change in a climax community?
Climate; it is always changing; this causes the biotic
and abiotic factors to change as well
22. What is left after a forest fire?
Ash and the burnt trees.
23. Define secondary succession.
The growth that occurs after a disturbance to an area that already has soil and was
once the home of living organisms
24. Compare the speed of primary succession to that of secondary succession.
100s of years vs 10s of years
25. Other then fire, list 4 other sources that result in secondary succession.
Flooding, drought, tsunamis, and insect
infestations.
26. List 3 negative aspects of flooding?
Increased soil erosion, soil pollution if toxic chemicals are present in floodwaters,
human diseases when toxins or harmful bacteria from untreated sewage enter drinking water supplies
27. What may occur to the soil after a tsunami has occurred?
Salt is deposited on the land which kills many plants
28. Give the definition of drought.
When there is a below-average amount of precipitation in an area over a period of many
months or years
29. What is the worst thing that can occur during a drought?
Habitat is destroyed when the plants and animals die
30. Which organisms benefit from mountain pine beetle?
Certain trees (Spruce, fir, and younger pines), woodpeckers and
nuthatches, some mammals
31. How does resin protect a tree?
Traps and flushes the adult beetles out of the tree
32. Describe the symbiotic relationship between the mountain pine beetle and the blue stain fungus. Beetle carries the fungus
from tree to tree spreading the fungus, the fungus destroys plant tissue and prevents the host tree from using resin to sweep
away both invaders.
33. Describe 2 factors that have prevented the control of the mountain pine beetle. Warm winters no longer kill beetles, human
fire suppression (stopping forest fires) prevent natural forest fires that would naturally destroy the home of the mountain pine
beetles.
34. Describe 3 negative impacts of the pine beetle.
Tree deaths destroy bird and mammal habitats, the economies of forestdependent communities are affected by loss of jobs
Answer key 3.2 How Humans Influence Ecosystems
p. 122
1. List 4 positive aspects of wetlands.
Filter out wastes, reduce the concentration of nitrate by > 80%, regulate climate by
retaining carbon, and hold great quantities of water which helps to prevent flooding
2. 2 common food grown in peat bogs in British Columbia are? Blueberry and cranberries
3. DYK, List the #s of different types of organisms currently living in Burns Bog of Delta.
200 sp birds, 10 sp of
amphibians, 6 sp of reptiles, 50 sp of mammals
4. How long does it take to form wetlands?
5000 years
5. List 6 things that wetlands have been turned into over the past 100 years.
Parking lots, subdivisions, garbage dumps,
agricultural land, and shopping malls
6. How much wetland has been lost in the southern Okanagan? 85%
7. Apart from losing biodiversity of plants and animals, what are scientists concerned will happen by drying out wetlands?
Carbon dioxide and methane will be released into the atmosphere contributing to climate change
8. Give the resource definition of sustainability.
Using the resources of an ecosystem to meet our needs today without
reducing the function and health of that ecosystem or the ability of future generations to meet their needs
9. What does a sustainable Earth require?
Society’s demand on nature is in balance with nature’s ability to meet that demand
10. Fg. 3.19, what is more important then recycling?
Reusing materials and reducing the amount we have to recycle
11. List 6 common land uses. Urban development, agriculture, industry, mining, and forestry
12. 6 common exports of B.C. are… coal, timber, minerals, fish, manufactured goods, and agricultural products
13. What is the main cause of habitat loss?
Increasing human population
14. What is the effect of habitat fragmentation resulting in isolated fragments?
Plant pollination, seed dispersal, wildlife
movement and plant and animal reproduction
15. Table 3.1, what are some of the considerations in the sustainable approach to urbanization?
Waste treatment, storm
water collection, native plantings, and other green areas are incorporated
16. Sustainable forestry practices include?
Leave some trees uncut, streambed restoration, less harmful road –building
17. How has the grassland ecosystem been altered?
Livestock grazing, recreational vehicles, and introduced plants
18. What are the eight benefits of polyculture?
Increases the amount of nutrients and helpful micro-organisms in soil,
reduces soil erosion and weed invasions, protects plants from pests and diseases , provides food and habitat for native animals
and financial security for the owners because thy are not dependent only one crop
19. How does deforestation cause soil erosion?
There are no plants to anchor the soil in place.
20. What is the problem with many of the non-sustainable coffee farms in Brazil? Developed on land that once was lush tropical
rainforest.
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21. DYK, how long does it take to form 2.5 cm of top soil? How much is lost due to erosion every year?
500 years, 25 000
000 000 000 kg/y
22. Fg 3.35 and 3.26 shows? Deforestation of tropical rainforest and the resulting species endangerment due to loss of habitat
23. What the main problem in North America when fields are left bare during non –planting seasons? Wind blows away the topsoil
24. What is the primary problem with run-off due to soil compaction?
Add excess nitrogen and pollutants such as
pesticides to the environment
25. Give 5 examples of resource exploitation. Harvesting fish and timber, mining coal & minerals, and extracting oil & gas
26. Fg 3.30 represents?
Untreated chemical and other wastes escaping into the environment
27. At the Britannia beach mine reclamation water treatment facility, what is removed and added to the water coming out of the
mine? 454 kg of cooper and even more other metals each day, he pH is adjusted to proper levels.
28. What 3 qualities make the plants in table 3.2 special?
Tolerate contaminated soil, absorb contaminants through their
root systems, stabilize the soil to prevent contaminants from leaching into water
29. What % of Atlantic cod remain in the oceans due to overexploitation in the last few decades?
10%
30. In addition to reduced numbers of the species, overexploitation also leads to loss of genetic diversity (variations within the
species). What problems do this cause?
Populations are less resistant to disease and less able to adapt to changes
in their environment.
31. Kelp are not only producers in the ocean but provide habitats for many marine creatures. Explain how the overhunting of sperm
and baleen whales 50 years ago has led to the destruction of the kelp forests and accompanying ecosystems today?
Fg 3.32 p. 132.  sperm whales & baleen whales  less food for orcas  switch prey   harbour seals, fur seals,
sea lions, sea otters   sea urchins   kelp  destroyed ecosystem
32. List 4 things that burning does for the environment.
Recycles nutrients and creates more diversity in the understory
of a forest, reduces forest litter that can lead to massive fires, opens the canopy allowing plants that require more sunlight to
grow in the understory
33. Another name for controlled bringing is?
Prescribed burning
34. Explore more.
List 4 advantages of biofuels.
Produce few green house gas emissions, minimizes toxic waste,
promotes rural economies by using local crops
35. List 1 serious negative aspect of biofuels. Increased deforestation to clear land to grow crops, less crop food for people
Answers ws 3.3 Introduced Species
p. 138
1. Define native species.
Plants and animals that naturally inhabit an area
2. How does purple loosestrife destroy the wetlands:
chokes out other plants and is too dense to shelter wildlife.
3. What is ballast? Heavy materials used to stabilize ships (ex water)
4. Give an example of how biological control works.
Leaf-feeding beetles are released into the area and they eat the
purple loosestrife as food
5. DYK, what was the problem with the invasive zebra mussel? Block off water pipelines, which affect water supplies to cities
and hydroelectric companies which depend o water for electric power generation
6. Give 4 synonyms for introduced species.
Foreign species, non-native species, exotic species, alien species
7. What is the problem with invasive species?
Take over the habitat of native species or invade their bodies thus
weakening their immune systems
8. 2 factors that increase the rate that invasive species are released into an area are?
Climate change and the expansion of
international trade and travel.
9. Why are invasive species a cause for concern?
Major cause of global biodiversity loss
10. What in danger in Saltspring Island’s Rucle Provincial Park with the release of the South American burweed?
4 rare
native plants
11. Why do introduce predators have more impact on a prey population then native predators?
Prey may not have
adaptations to escape or fight the introduced predators
12. What is the problem with crazy ants on Christmas Island?
They devour all plants and also prey on the young of reptiles,
birds, and mammals
13. Define keystone species. Species that can greatly affect population numbers and the health of an ecosystem
14. How does the release of invasive parasites or disease-causing viruses and bacteria severely alter the ecosystem?
They can weaken the immune responses of the ecosystem’s native plants and animals thus providing opportunities for
less dominant species to outcompete other species.
15. Describe 3 positive functions the Whitebark pine tree serves in the Rocky Mountains?
Controls the snow melt in the spring,
provides cover and shelter for many species, provides food in the form of seeds for animals.
16. 1 unusual attribute of the Whitebark pine is that it is the only tree that grows in the very windy areas of the Rocky Mountains,
what is the problem with it’s incredibly slow reproduction: fg 3.40?
It will not be able to develop resistance to
blister rust before severe damage is done
17. Why are prescribed burns being done in these areas?
To create more forest openings for new Whitebark pines to
develop and to kill off lodgepole pine trees that also live in the area that also attract more mountain pine beetles which can
attack more Whitebark pine trees
18. List 5 of the ways that introducing an invasive species can change the structure or composition of the natural habitat.
Light levels, dissolved oxygen in water, soil chemistry, increase soil erosion, nutrient cycling, pollination and energy
flow
19. Describe the type and method of how the Eurasian milfoil can be controlled?
Biological control, a native weevil is cultivated
(grown) and put in the lake
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20. Why were American bullfrogs introduced to BC and why how are they being controlled?
For food, remove tadpoles as
soon as they hatch from eggs
21. What type of biological control is being attempted to control starlings?
Barn owls
22. How does the invasive Scotch broom affect the soil? Due to nitrogen fixation, it overloads the soil with nitrogen
23. What adaptations does the invasive grey squirrels have over the native red squirrels?
Large, stronger, can store more fat
24. How does the gypsy moth damage the Gerry oak trees?
Eats all the leaves so that the tree can not undergo
photosynthesis
25. p. 145
What are rats credited for on islands around the world?
90% island Seabird and reptile extinctions
26. Why are these island rats able to increase their populations so quickly? No predators
27. What is the main method being tested to eliminate these invasive island species?
poison
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