6.6 Populations And Sustainability Flashcards
Population
number of organisms existing in a particular area
Growth curve
A = lag phase
B = log phase
C = stationary phase
Lag phase
when there are few individuals who get used to their habitat and start reproducing while the rate of reproduction is still low
Log phase
when there are lots of resources, conditions are good (reproduction is favoured), rate of reproduction>rate of death
Stationary phase
when rate of reproduction = rate of death, because the population has reached its carrying capacity
Carrying capacity
maximum population size that can be maintained over a period of time in a habitat (based on biotic and abiotic factors)
What happens if you exceed the carrying capacity
there will be a decline phase = bc there’ll be a limiting factor
Why do you reach carrying capacity
Bc of limiting factors
2 types of limiting factors
Density dependent and density independent
Density dependent factors
limiting factors whos power increases when density of the population increases e.g. predators, food, water, oxygen
Density independent factors
limiting factors that do not depend on the population size e.g. temperature, natural disasters
2btypes of strategists to reach carrying capacity
R strategists and K strategists
K strategists
growth curve = closer the population reaches to carrying capacity, the stronger the effect of limiting factors = gradual levelling out, system followed by populations like large mammals, humans
Features that allow us to follow K system
low reproduction rate, slow development, late reproductive age, longer life span, large body mass
R strategists
population size increases so quickly it exceeds carrying capacity, then limiting factors start to have an effect, then it goes back down. Usually bacteria or pioneer species
R strategists population growth curve
Features that cause people to follow the R system
high reproductive rate, short life span, long reproductive age, quick development, small body mass
2 types of competition
Interspecific and intraspecific
Interspecific competition
Between individuals of different species
Intraspecific competition
between individuals of same species
What is intraspecific competition proportional to
Most intraspecific competition is proportional to population size
If population size goes down, competition goes down, which then means the population size goes back up again
Effect of interspecific competition
Within interspecific population bc it’s impossible for 2 species to occupy the exact same niche, one species will often out compete the other species = 2nd species levels will be rlly low
What does it mean if only one species will win due to competition
Competitive exclusion
Problem w tryna recreate competition in a lab to see it’s effect
competition isn’t the only factor that impacts growth
Factors that may lead to decrease in population
- Change in temperature
- Change in ocean current
- Change in food
- New diseases/parasites
- Change in predators
- New species present on land
Predators and prey
Is the predator and prey cycle really like the graph!
No bc lab doesn’t take into account all the other factors that affect population.
Conservation
active management using human interaction to maintain biodiversity by allowing sustainable use of resources (human intervention)
Preservation
maintaining biodiversity in their present condition = minimise human activity on habitat
Threats to biodiversity
Threats to biodiversity
- over exploitation of resources e.g. fishing at a higher rate than fish replenish themselves
- Habitat disruption + destruction
- Species introduction
Species introduction
introduce species to diff islands that can put compete the native species
Ways to conserve biodiversity
- Organisations e.g. national parks, zoos, botanical gardens
- Vaccination programmes
- Control predators
- Reduce pollution = starting legislations or limiting how many tourists can visit a place per year
- Coppicing
Importance of conservation
Ethical, economical, social reasons
Ethical reasons for conservation examples
species have values, it’s our responsibility to look after them
Economical reasons for conservation examples
certain species when harvested they make money, food sources, medicine, natural predators can act as biological control agents e.g. instead of having to use pesticides and herbicides there’s already organisms that act like that
Social reasons for conservation examples
greenery is good for mental health, tourism, ecotourism
Aim of sustainability
- ensure enough resources for future generations
What does sustainability do
- Enable less economically developed countries to develop (can harvest their w unique/special resources that people can use to replace or replenish things we’re using up already
- Balance consumption of resources between more and less economically developed countries.
Ways to fish sustainably
Limit size of fishing fleet = people given license to go and fish
Inspect catch when fishing boats return
Banning certain practices e.g. static nets
What is sustainable fishing
maintaining amount of fish + protecting habitats
Who control sustainable fishing
Marine stewardship council control sustainable fishing
Fishing must be managed
Fishery must be adapt to changes and comply w local and national regulations
2 types of small scale timber production
Rotational coppicing and pollarding
Rotational coppicing
- split area into sections and coppice one area at a time
- trees are cut near the base = shoots can grow from cut area = more wood
Advantages of coppicing
Quick and more branches but can easily be eaten by herbivores
No trees block sunlight = no succession = maintains biodiversity
Pollarding
Cutting the tree trunk at a higher space so more shoots can grow from the cut area
Higher = can’t be eaten by herbivores = protected
Large scale timber production
Felling large area of forests
Felling large area of forests
- deforestation = will not regrow
- not sustainable and can cause other problems e.g. soil erosion due to a lack of tree roots to protect the soil and its nutrients
Ways to improve large scale timber production
- Selective cutting = only cut some trees
- replant trees at optimal distribution = avoid competition
- manage pests and pathogens
- ensure protected areas for locals
Advantage of trees
add minerals to soil and remove water from soil = stops soil from being washed away by rain + polluting nearby waters
The terai region
- found in Nepal
- Home to bengal tigers and one horned rhinoceros
- problem is under pressure bc agriculture has expanded in the forest area, grazing from farm animals and over exploitation of forest resources is a problem
- Solution = WWF have funded people living there will be provided with the necessities e.g. fuel, food, medicine = won’t need to go to forest to gather these things
- WWF also helped them gain off farming skills e.g. entrepreneurial skills + helping to create forest corridors = separate paths for humans
Maasai Mara
- Kenya
- contains loads of wildlife + popular for tourism + home to poverty
- Problem = putting wildlife in danger = solution international organisations paid locals a certain amount to conserve a portion of the land but said to them during peak tourist months all livestock had to be moved
- Important for tourism!! Aim is to reward locals for tourist activity that occurs there
Galapagos island
- special species e.g. Darwin’s finches, giant tortoises and endangered plant species
- Problem = more people visiting island and causing damage, more waste and pollution, higher demand for oil
- Each time people come to the island they introduce their own species that eat + destroy native species and being diseases onto the island e.g. cats feed on young iguanas and goats feed on Galapagos rocks = disturbed habitat for giant tortoises
- Plant called red quinine = invasive specie
- To manage the island they started searching any boats that arrived to the island + used natural predators, culling = kill goats, education
Antarctic
- problem is tourism + increase in scientists due to research interest
- Problem from fishing industry
- Known for krill’s, fishing for krill quite common = bad bc food for whales and penguins
- To avoid over exploitation there’s a catch size limit on how much krill u can catch per area
- Place also has protected areas which makes it illegal to hunt + kill whales in certain places in the island
- Antarctic also has two famous birds, albatrosse, petrels = native to island but affected by human activity e.g. pollution, hunting, poaching for eggs, Fishing nets capture birds
- Now boats have been asked to use bird scaring lines to prevent birds from attaching to them + use lines at night to avoid birds being affected
The Lake District
- UK.
- a national park which has sheep’s and livestock that feed on the grass = without this it would reach climax community so it’s important for this to happen
- Threat: humans (walk on land) = farmers paid to maintain their land, to reduce chemical use
- Also cliffs and rocks support rich diversity of plant life = damaged by climbers, walkers and to protect them there are seasonal restrictions on where you can and can’t walk and education to be more aware of paths you should walk on
- Invasive species that come from peoples gardens into the woodlands. Problem = outcompete native species. Solution = invasive species are physically removed by conservation workers
Snowdonia
- UK
- Same problem as Lake District (walkers and climbers) solution = good footpaths maintained to prevent walkers from stepping on living organisms
- Gutters that take waste water but can be blocked from waste by tourists. To prevent this there is a team of workers that clean the rubbish (volunteers)
- National park works w local farmers to reduce sheep grazing on the mountains
- Location of goats are monitored so they don’t feed everywhere
- Rare birds that can nest in snowdonia e.g. hen harrier and Merlin
- Also have rare butterflies.
- Incentive = money to farmers to protect their lands
Peat bogs
- wet area that has lots of life
- Problem = people usually burn them
- Carbon sink = store of carbon dioxide. Good bc if u burn it you can use it as fuel
- Negative = you add carbon dioxide to the atmosphere
- The fact that it’s really moist = absorbs lots of water so it prevents too much water from reaching the plant = improves soil structure = commonly used by gardeners
- Peat contains lots of wet vegetation e.g. mosses, shrubs = good for the growth of certain plants r.g. Mosses, cotton and allows a wide range of insects to grow on it e.h. Butterflies, moths. Really good for birds to nest on bc it doesn’t attract predators
- Threat = peat bogs are being removed/extracted
- Organisations work to preserve these ecosystems
Issue w overgrazing
Disrupts food chain
