6.6 - Populations and sustainability

Question 1

What happens to the number of organisms in a population over time?

Answer 1

Phase 1) At first development and population growth is slow
[In the first phase the birth rate is higher than the death rate]
Phase 2) The growth in the population size rapidly increases, there is very few limits on population growth
Phase 3) The stable phase, further growth is limited due to external constraints, this causes fluctuations in growth of the population
[The carrying capacity is met]
The carrying capacity is not subject to any more succession

Question 2

What is carrying capacity?

Answer 2

• When the population reaches its maximum size that the environment can support
• The populations are then not subject to any further succession

Question 3

How can populations be affected by different factors?

Answer 3

• If all resources are available in a plentiful supply the population would grow exponentially
• Limiting factors can be categorised into abiotic (Non-living) and biotic factors (Living factors)
• Other variables that can affect population growth include immigration and emigration
• Immigration is the movement of organisms into the area
• Emigration is the movement of organisms out of the area

Question 4

What is immigration?

Answer 4

-Immigration is the movement of organisms into the area

Question 5

What is emigration?

Answer 5

-Emigration is the movement of organisms out of the area

Question 6

What are some examples if abiotic factors?

Answer 6

• Nutrients
• Oxygen
• PH

Question 7

What are some examples if biotic factors?

Answer 7

-Intraspecific competition and interspecific competition
 such as:
-Finding a mate
-Predators
-Parasites

Question 8

What is interspecific competition?

Answer 8

• Competition between two species
• For example: The leaves on the surface of the water blocking the sun for organisms in the water, they are from different species’ but both competing for the sun
• For example: The grey squirrel has out-competed the native red squirrel for food so the populations of grey squirrels is higher

Question 9

What is intraspecific competition?

Answer 9

• Competition between the same species
• For example: Bower birds compete with other bower birds to win over mates, via creating a vibrant bower in order to attract the female bird

Question 10

What is predation?

Answer 10

-Predation is another biotic factor that can influence population size
-Many predators have evolved ways to catch their prey (E.g: Speed and stealth)
-Likewise, the prey evolve ways to avoid capture
(E.g: Camouflage, stings and mimicry)

Question 11

Describe how the population of prey can affect the population of predators? (Seen in a predator-prey graph)

Answer 11

• As the population size of the prey increases, the predator does the same as there is more to eat
• However, as the population of the predator increases, the population of the prey starts to decrease as it is eaten by the predator
• The predator has less food to eat so the populations of predators then also go down
• Etc…

Question 12

What factor affects the predator on a predator-prey graph?

Answer 12

-The availability of food (Prey) for the predator

Question 13

What factor affects the predator on a predator-prey graph?

Answer 13

-The over predation of the prey’s species by the predator

Question 14

Explain the relationship between birth rate and death rate in a population which is increasing/decreasing in size?

Answer 14

• If the birth rate is higher than the death rate then the population size will increase
• If the death rate is higher than the birth rate then the population size decreases

Question 15

What is conservation?

Answer 15

• The maintenance/management of nature to protect habitats and species’
• For example: The conservation of a woodland to protect the trees and habitats inside it
• For example: Conservation parks in Africa that help protect the species within them

Question 16

What is preservation?

Answer 16

-Leaving the ecosystem untouched by humans in order to protect habitats and species’

Question 17

Why is conservation important?

Answer 17

• Economic reasons, Ecotourism can benefit countries massively as it can provide tourism and bring lots of money into the country/areas. Ecosystems also have potential to provide future medicines
• Social reasons, conservation is important as it stops the impact of deforestation. Also, socially, ecosystems can be important due to their aesthetics and the positive impact they can have on people’s mental wellbeing
• Ethical reasons: Preserving ecosystems can stop extinction. Also conservation can work to support the indigenous people

Question 18

What are the aims of sustainability?

Answer 18

• To preserve the environment
• To ensure resources are available for future generations
• To allow humans in all societies to live comfortably
• Enables less economically developed countries to develop through exploiting their natural resources
• To create a more even balance in the consumption of these resources in more economically developed countries

Question 19

What is coppicing?

Answer 19

• When the trunks are cut close to level ground
• Several new shoots grow from the cut surface
• The process is repeated after a certain amount of time
• The young shoots must be protected from grazers
• This process can be repeated indefinitely as the tree can just grow back

Question 20

What are the advantages of coppicing?

Answer 20

• New stems grow more rapidly than saplings
• The lifespan of the tree is extended
• It provides a variety of light levels to for the habitat
• Fewer large trees means there is more light that is available for smaller plants
• It maintains biodiversity as it can provide a variety of habitats
• The roots are present and not removed, so this prevents soil erosion
• It maintains soil quality
• Prevents succession
• Large machinery is not needed so there is less disturbance of the habitat

Question 21

What is selective felling?

Answer 21

• The cutting down of selected, mature trees in a forest

- This allows other trees to grow to maturity and also leaves enough for habitats and for animals

Question 22

What is rotational felling?

Answer 22

• This consists of planting a site and then felling the trees when they have reached maturity
• After felling the trees on one site, the site is left to grow and a different, mature site is felled
• Depending on tree species, it usually takes between 8 and 20 years for the trees to grow and mature back to a state where they can be felled again

Question 23

What is strip felling?

Answer 23

• The cutting down of selected, mature trees in a strip formation through a forest
• This allows other trees to grow to maturity and also it leaves enough for habitats and animals

Question 24

What should be done with felled trees to ensure sustainability?

Answer 24

-The trees that are felled should be replanted to grow and produce timber

Question 25

How is sustainable fishing be brought about?

Answer 25

• Quotas are introduced to limit the numbers of certain species of fish that can be caught
• Certain hole sizes in nets are made to allow smaller fish to escape to reach maturity and their breeding age, this maintains a sustainable level of the population
• Fishing is only allowed at certain times of the year, this allows the population to reach a sustainable level

Question 26

What is the conflict between conservation/preservation and human needs in Masai Mara region in Kenya?

Answer 26

• Poaching has lowered the animal population numbers, therefore park rangers have been employed and provided with necessary equipment to combat the poaching
• Elephants trample on crops, therefore farm land is fenced off
• Legal hunting of overpopulated species is allowed at certain times to stabilise or maintain the ecosystems population levels and to provide food for the humans in the surrounding area

Question 27

What is the conflict between conservation/preservation and human needs in the Terai region of Nepal?

Answer 27

• Forests are being cleared to make products, to combat this, governments have increased the retail price of forestry products which has lead to a greater economic input to the region so less deforestation has to occur for people to gain an income
• There are more sustainable wood fuel sources which has discouraged deforestation as there are substitutes for using timber as a fuel
• There is promotion of fruits/veg from other areas to prevent destruction of habitats
• There is improved irrigation for crops, this has been done as the soil quality has decreased overtime due to the removal of nitrogen from the soil without replenishing it
• Nitrogen fixing plants are used more, to replenish and improve the quality of the soil

Question 28

What is the conflict between conservation/preservation and human needs in peat bogs?

Answer 28

• Peat bogs are extracted and used for fertilisers on plants however the peat bogs take thousands of years to form
• The peat bogs support some rare species of plants
• The peat bogs are very acidic
• Peat bogs are conserved by removing large trees from the water as the trees will take in the water from the ground that is needed in the peat bogs
• Grazing of sheep and cattle is prevented in order to protect the rare species of plants within the peat bogs

Question 29

What is an endemic species?

Answer 29

A species that is not found anywhere else in the world

Question 30

Why is the Galapagos Islands a desirable destination for humans?

Answer 30

-The Galapagos Islands are home to many Endemic species that are found nowhere else in the world

Question 31

How has the Galapagos Islands been effected by humans?

Answer 31

• There has been habitat destruction for buildings and roads
• There has been deforestation of land that is used for farming to provide for the humans
• There has been overgrazing of land by species that have been introduced by humans, species’ that have been introduced to the Galapagos Islands have out-competed native species’ for food so the native species population has decreased due to the humans
• There are more boats in the water which can cause more pollution, sewage and oil spills in the sea which can kill marine life
• There is overfishing which decreases the population sizes of some fish species’
• Humans have collected eggs from animals to eat, this also can negatively effect the populations of species’ on the island
• New pathogens/diseases have been introduced to the island, this can kill off species and negatively impact the populations of rare animals on the Island as they have not come into contact with pathogens that are brought over by humans

Question 32

How is the impact of humans on the Galapagos Islands controlled?

Answer 32

• Park rangers have been introduced, this limits human access to particular islands to protect the endemic species that live in specific parts of the Island
• There is also stricter control on migration and the introduction of animals (I.e: Animals are quarantined before entering the island)

Question 33

How has the animal and populations in Antarctica been effected by humans?

Answer 33

• Whale and fish populations have been impacted through overfishing and whaling
• There are now bans on whaling and restrictions on fishing
• Waste must now be taken with you when you leave Antarctica, boats are also prevented from dumping their waste in the sea so sea life can increase their population sizes without pollution and without their habitats being destroyed

Question 34

How is the impact of human activities on Snowdonia National Park and the Lake district controlled?

Answer 34

• Visitors are now encouraged to use paths to protect native species
• Litter is encouraged to be placed in bins or taken home with you upon exit
• There is a speed limit on boats to protect the habitats in the lakes or surrounding the lakes