carrying capacity
the largest population that an ecosystem can support
interspecific competition
competition between members of different species
intraspecific competition
competition between members of the same species
abiotic factors that affect population size
wind, temperature, light, pH, water and humidity
Mark-release-recapture
1. capture first sample, mark them and release into their habitat2. ensure the marking doesnt harm or increase predation3. leave enough time for organisms to randomly mix4. recapture a sample number in 1st sample x number in 2nd sample / number marked in 2nd sample
assumptions made in mark release recapture to be valid
1. marking isnt removed2. sufficient time to mix 3. no / limited migration 4. few births and deaths 5. sampling the same for both captures
frame quadrats
1. use a random number generator to find coordinates of an area youve previously turned into a grid (avoids bias)2. use a large sample size (20 quadrats) and place them at the coordinates 3. count the number of organisms in each quadrat4. calculate a mean by repeating the experiment and using a stats test to avoid chancesize of field / quadrat area x number of species = population size
Belt transect
1. lay rope / tape measure along area2. rope / tape measure has equal markings at regular intervals 3. place frame quadrats at each interval4. count number of species inside the quadrats 5. use several transects to find a mean and carry out a stats test
Species
A group of organisms that can breed and produce fertile offspring.
Population
amount of individuals in the same species
Community
All the different species that live together in an area
species richness
the number of different species in a community
Niche
An organism's particular role in an ecosystem, or how it makes its living.
habitat
Place where an organism lives
food source
What an organism obtains its energy from.
biotic factors
living parts of an ecosystem
abiotic factors
non living / chemical parts of an ecosystem
Ecosystem
a combination of biotic and abiotic factors
Biodiversity
The number of different species in an area and how many in each species
sessile organisms
organisms anchored and cant move
motile organisms
Organisms that can move
ecological succession
1. pioneer species colonises a harsh environment2. death of pioneer species releases nitrogen compounds and causes soil / humus to form3. this makes abiotic environment less hostile4. this enables other species to colonise increase biodiversity5. pioneer species eventually outcompeted6. after 100 years a climax community is created
3 features of a climax community
1. same species present over long period of time 2. population sizes are stable 3. abiotic factors are stable
conservation
maintain the natural biodiversity of an ecosystem
Methods of conserving habitats
1. seedbank stores2. fishing quotas 3. protecting natural parks and nature reserves 4. breeding endangered species in captivity
conservation practices to increase biodiversity
1. maintain hedgerows2. dont create monocultures, use intercropping3. dont fill in ponds and wetlands4. keep animals contained while grazing5. stop using pesticides, use natural fertiliser6. plant trees in low biodiversity areas