Biodiversity 🦫 Flashcards
Define biodiversity:
Variety of living organisms present in an area
Why is biodiversity important?
Essential for maintaining balanced ecosystem–> all species interconnected
Balanced ecosystem = food, oxygen
How is biodiversity measured?
Habitat
Species
Genetic
What is habitat biodiversity?
Refers to number if different habitats found within an area.
Habitat = supports range of species
Habitat rich = species rich
What is species biodiversity?
Species richness = number of diff species living in particular area
Species evenness = relative abunance of diff typesof species living in an area
What is genetic biodiversity?
Variety of genes that make up a species.
Many genes = many diff alleles = genetic BD
Greater genetic BD = better adaptations to changing environment = resistant to disease
What is sampling?
Taking measurement of limited individual organisms present in particular area.
Used to estimate number of organisms in area w/o counting them all.
Used to measure particular characteristics of an organism
What is random sampling?
Selecting individuals by chance.
Each individual in a population has equal likelihood of selection.
e.g: take x and y coordinates of a grid
What is non-random sampling?
Opportunistic: weakest/not representative as uses organisms conveniently available
Stratified = population divided into strata on characteristics.
–>Random sample taken from each strata
proportional to its size.
Systematic: different areas within overall habitat identified –> sampled separately.
(normally done with line transect.
Are samples reliable?
Never entirely representative
Sampling bias –> human involvement
Chance –> minimise with larger sample size
How are animals sampled?
Pooter = small insects –> suck on mouthpiece so insect drawn into holding chamber via inlet tube
Sweep nets = insects in long grass
Pitfall traps = small crawling invertebrates (beetles/spiders/slugs) deep enough so they can’t crawl out
Tree beating: samples of invertebrates in bushes –> animal fall into white cloth
Kick sampling: study organisms in a river.
–>river bed kicked for period of time-> disturbs surface.
How are plants sampled?
Quadrat–> can also sample slow moving animals (barnacles/limpets)
Describe a point quadrat:
Frame containing vertical bar.
Long pins pushed through bar to reach ground at set intervals
every plant pin touches = recorded
What is the difference between a line and belt transect?
Line = number of species touching line along transect
Belt = quadrats placed along transect
Describe frame quadrat:
Square frame divided into grid of equal sections
type + number of species within each section of quadrat recorded.
Done with random sampling techniques.
How to measure species richness/evenness?
Richness = identification key to classify organism
Evenness = Log number of each species in environment + see if species evenly distributed among population
What are the 3 main ways to sample population using frame quadrats?
Density:
~~~~> large plant seen clearly = count them in 1 m by 1m square quadrat –> gives density per square metre. (absolute measure)
Frequency:
~~~~> when individual members of a species = hard to count (grass/moss). Each 1 square of 100 = 1%
Percentage cover:
~~~~> used for speed, lots of data collected quickly. Useful when species abundant/difficult to count
Samples taken at diff points
Mean value = individual quadrat results ➗ number of samples taken
total pop = area x mean value per m^2
How can we estimate animal population size?
Capture-mark-release-recapture.
Capture as many species as possible
Mark species
release into wild
another sample collected
estimate pop size
How can we measure abiotic factors?
wind speed –> anemometer (ms-1)
light intensity –> light meter (lx)
relative humidity –> humidity sensor (mg dm-3)
pH –> pH probe
temperature –> temperature probe
oxygen content in water –> dissolved oxygen probe (mg dm-3)
