Populations and sustainability

Question 1

3 main phases of population growth (graph)

Answer 1

1. Lag phase- species acclimatising to habitat, so reproduction is slow
   2.Log phase- good conditions, so reproduction happens quickly
2. Reaches carrying capacity- the habitat can’t support a larger population

Question 2

Carrying capacity

Answer 2

-the maximum population size a habitat can support

Question 3

2 types limiting factors on population size

Answer 3

-Density independent- act just as strongly, irrespective to population size eg. low temperatures
-Density dependent- factor influences the population more strongly when the population size is large eg. predation, availability of resources

Question 4

K- strategists
definition, examples, characteristics

Answer 4

-species whose population size is determined by the carrying capacity
eg. large mammals, birds
Characteristics:
-low reproduction rate
-slow development
-late reproductive age
-long life span
-large body mass

Question 5

R- strategists
definition, examples, characteristics

Answer 5

-population size increases so rapidly that it exceeds the carrying capacity (boom) before limiting factors start to haven an effect (bust)
eg. mice, insects, weeds
Characteristics:
-high reproductive rate
-quick development
-young reproductive age
-short life span
-small body mass

Question 6

2 types competition

Answer 6

-intraspecific
-interspecific

Question 7

Intraspecific competition

Answer 7

-competition between members of the same species
-food supplies become limited, so those better adapted survive, and others die
-keeps population stable as when population increases, competition increases, causing population to decrease

Question 8

Interspecific competition

Answer 8

-happens between individuals of different species
-the more overlap between the 2 species niches, the more competition
-competitive exclusion principle- 2 species can’t occupy the same niche
-can cause extinction or the population of one of the species to decrease

Question 9

Preservation

Answer 9

-maintenance of habitats and ecosystems in their present condition, minimising human impact

Question 10

Conservation

Answer 10

-active management process including human intervention

Question 11

3 threats to biodiversity

Answer 11

-over exploitation- species are harvested at a greater rate that they can replenish
-habitat disruption due to pollution, agriculture, building
-species introduced to an ecosystem, causing competition

Question 12

Conservation strategies

Answer 12

-increase carrying capacity by providing food
-more individuals to enlarge populations
-restrict dispersion of individuals using fences
-control predators/poachers
-vaccinate

Question 13

Why conserve?

Answer 13

1. ethics- every species has value and humans have repsonsibility to look after the animals
2. social + economic- provide a valuable food source, natural environments provide wild plants for drugs etc, predators of pests act as biological control agents

Question 14

Managing small scale timber production

Answer 14

-coppicing- stems from deciduous trees are cut close to the ground. New shoots grow from the cut surface and mature into stems to be cut again
-pollarding- cutting stems higher up to prevent deer from eating the shoots
-rotational coppicing- managers cut on section of wood per year to provide a consistent supply

Question 15

Managing large scale timber production

Answer 15

-used to fell all trees in one area, destroying the habitat
-they avoid felling nowadays by sticking to 3 principles:
1.any tree harvested must be replaced with a new one
2. the forest must maintain ecological function
3.local people should benefit from the forest
-this is done by selective cutting- chose the largest and most expensive trees to cut. These provide more wood, meaning less tress have to be cut

Question 16

Managing fish stocks- fisheries
3 principles for sustainable management

Answer 16

1.fishing must take place at a level which allows it to continue indefinitely
2.fishing must be managed to maintain structure, productivity, function and diversity of the ecosystem
3.fisheries must adapt to changes in circumstances and comply with fishing regulations

Question 17

Managing fish stocks- aquaculture

Answer 17

-the rearing of aquatic animals or the cultivation of aquatic plants for food
-provides sustainable fish stocks
-raising stocks in aquaculture restricts the impact on oceanic fish stocks and less people will be have to fish in oceanic fish stocks

Question 18

Balancing conflict between conservation and human needs- Terai region

Answer 18

-south nepal
-pressure from over agriculture, animal grazing, over exploitation of resources, home to endangered species eg bengal tiger
Strategy:
-conserve forest as a whole by introducing community forest initiatives
-construct waterholes
-monitored endangered species
-eradicated invasive species

Question 19

Balancing conflict between conservation and human needs- Maasai Mara

Answer 19

-Kenya
-over poaching of certain animals has caused a decrease in population
-employed park rangers to prevent poaching of endangered animals
-poaching allowed for overpopulated species at certain times

Question 20

Peat bogs

Answer 20

-forms where lack of oxygen prevents complete decomposition of waste due to the area being waterlogged
-carry lots of historical data as they accumulate over thousands of years
-peat is used as compost in gardens

Question 21

Controlling effects human activities: antartic

Answer 21

-Southernmost continent
-coldest, highest, direst, windiest, emptiest continent
-endothermic animals thick blubber for insulation eg. weddell seal
-plants only grow on ice free regions eg. lichens + moss
-affected global warming, hunting whales, overfishing etc

Question 22

Controlling effects human activities: galapagos islands

Answer 22

-eastern pacific ocean, south of mexico
-pop increase place demands energy, water, more pollution produced
-building and conversion of land for agriculture causes fragmentation habitats
-fur traders killed tortoises
-depletion sea cucumber, effects underwater ecology
-foreign species being introduced eg. goats that feed tortoises
-managed by searching boats for foreign species, foster culture of conservation and educate, marine reserves where 36%= no take zones

Question 23

Controlling effects human activities: lake district
3 threats and solutions

Answer 23

1.invasive species compete with the woodland- conservation workers physically remove invasive species
2.cliff and rock damaged by walkers which are habitats for eagles, falcons- seasonal restrictions on walking when birds are nesting
3.hay meadows under threat as demand decreasing, supports rich diversity of flowers and grasses- farmers paid to maintain hay meadows

Question 24

Controlling effects human activities: snowdonia national park
2 impacts and solutions

Answer 24

1.farmers dig drainage ditches, causing poor water quality in rivers- drainage ditches blocked by hay bales
2. conifers planted dry out moorland and roads built to transport wood- branches used block drainage ditches to slow water flow, keeping land moist