Mr Allsop- biodiversity Flashcards
what is biodiversity
the number of different ecosystems and habitats in an area, the number of species within ecosystem and genetic variation within each species
habitat
where an organism lives
species
group of organisms of common ancestry that produce fertile offspring
3 levels of biodiversity
habitat, species, genetic
habitat biodiversity and what factors effect this
number of different habitats in an area .
abiotic factors- temperature, light, water, PH, humidity
biotic- food webs, competition, food , predators
species biodiversity
number of different species ( richness) and abundance of each species ( evenness)
may have same number but one more diverse
genetic biodiversity (+-)
variation of alleles within species
allows for better adaptation to changing environment
limited in small populations, more chance of interbreeding
what is sampling
taking measurements of a limited number of individual organisms present in a particular area
what are 3 things the sample should be representative of
size of area/ length of transect
repeat measurements
different times of year ( seasons)
species richness
number of different species
species evenness
measure of relative abundance of different species in the area
what is a quadrat used for (3)
1-species frequency- % of quadrats that include each species
2- species density- no.of organisms in quadrat (m2)
3- percentage cover- % of area quadrat in which plant, animal occurs
how to calculate species frequency
no.of quadrats with species/ total quadrats x100
what is random sampling
randomly generates coordinates to ensure everywhere has an even probability of being chosen
strengths and weaknesses of random sampling
+- less bias as is equal chance of coordinates being chosen
– may only cover one area if coordinates come out same
what is opportunistic sampling
makes decisions based on prior knowledge e.g. may sample a specific area they know the species will be
what are strengths and weaknesses of opportunity sampling
+- more chance of species being present
– bias as they have prior knowledge
what is stratified sampling
studies 2 areas and takes data from both e.g. meadow grass and short grass
what are strengths and weaknesses of stratified sampling
+- takes into account multiple areas
– over representative as only looks at 2 areas a lot
what is systematic sampling
samples taken at fixed intervals along a transect
belt transect- taken along continuously
interrupted belt transect - record quadrats at set intervals
line transect- record only the species touching the transect line
what are strengths and weaknesses of systematic sampling
+- more representative
– bias as other species may be missed
what is a pooter
suck small animals into glass or plastic tube
what is a pitfall trap
cans/jars buried in ground, filled with paper to allow shelter and covered with a lid on stones to stop water getting in.
what is capture-mark-release-recapture method
get a certain number of animal and mark it then release it, after a certain time to allow them to mix in population, then catch second sample, the smaller amount of marked the bigger the population
what is the beating tray method
large white sheet placed under tree and tree shaken to allow insects to drop out of habitat
what is a sweep net
large nets to catch flying insects or live in long grass