ATAR Unit 3 (1) Flashcards
biodiversity
variety of all living things; derived from ‘bio’ - meaning life & ‘diversity’ - meaning variability
three levels of biodiversity
genetic diversity - variety of genes within a species
species diversity - variety of species within a habitat
ecosystem diversity - variety of ecosystems in a given place
why is biodiversity important ?
increases ecosystem stability / resilience
provides commodities for humans [e.g. medicine]
random sampling
sampling randomly to capture an unbiased representation of an ecosystem
systematic sampling
sampling orderly through transects [lines / belts across the site]
stratified sampling
sampling separately by identifying areas within the site & dividing them into zones [strata / layers]
quadrat sampling
sampling using quadrats
line transect
sampling using straight lines w. set intervals
belt transect
sampling using straight lines w. quadrats
species richness
tally of number of different species within a particular area
number of species divided by square root of total number of individuals
percentage cover
measurement of the proportion of an area covered by an organism
ground cover [area]
basal cover [stem area]
canopy cover [total aerial cover]
organism’s cover divided by total area
multiplied by a hundred for percentage
percentage frequency
measure of how often a species of plant appears within the quadrats sampled
number of quadrats with the species of plant divided by number of total quadrats multiplied by a hundred for percentage
species abundance
number of individuals of a particular species in an area
number of individuals of a species
species evenness / relative abundance
measure of number of individuals of a particular species in relation to total number of individuals of all species in an area
species abundance divided by number of total individuals from all species multiplied by a hundred for percentage
simpson’s diversity index
measurement of both species richness and species evenness
1 − {[∑n(n−1)] / [N(N−1)]}
n : number of individuals of a specie
N : total number of individuals of all species
distribution
where an organism is found
abundance
how many of an organism is found
biotic factors
predator & prey
competition
symbiosis
abiotic factors
temperature
light intensity
water availability
limit on distribution & abundance of species [biotic]
if distribution / abundance of a species changes, distribution / abundance of other species it interacts w. changes [e.g. prey availability determines predator distribution & abundance]
limit on distribution & abundance of species [abiotic]
distribution is confined to a tolerance range
abundance is greatest in an optimum range & decreases outside this range
interspecies competition
competition for resources [food, mates, etc…] between members of different species [e.g. predators of different species hunting for the same prey]
intraspecies competition
competition for resources [food, shelter, etc…] between members of the same species [e.g. males of the same species competing for the same mate]
predator-prey
one species kills & eats another species [e.g. eagles hunting rabbits]
parasitism
one species [parasite] lives & feeds from another species [host] [e.g. leeches in humans]
mutualism
both species benefit [e.g. algae providing food for fungi & fungi providing protection for algae in lichen]
commensalism
one species benefits & the other species is unaffected [e.g. clownfish receiving food & protection from anemone]
