Biodiversity Flashcards
Biodiversity
A measure of the variation found in the living world
Habitat
Where an organism lives
Habitat biodiversity
The range of habitats in which different species live i.e. woodlands, parks
Species
A group of organisms that can freely interbreed to produce fertile offspring
Genetic variation
Variation between individuals that belong to the same species i.e. different breeds of dogs
Why do you need to use samples to measure a habitat
-impossible to count all the species present
What is a sample
A selected small portion of the habitat
-multiply the number of each species found in order to estimate the whole habitat
-Important to take samples that are representative of the whole habitat
What are the different sampling types
-Random
-Opportunistic
-Stratified
-Systematic
Random sampling
Sample sites randomly selected
-Use randomly generated coordinates to where you get your samples
-Selecting coordinates from a map and using a portable global-positioning satellite system to find the exact position within the habitat
Advantages of Random sampling
Ensures that the data is not biased
Disadvantages of Random sampling
-May not cover all areas of the habitat equally
-Species with a low presence may be missed leading to an underestimate of biodiveristy
Opportunistic sampling
The researcher makes sampling decisions based on prior knowledge/ during the process of collecting data
Researcher may deliberately sample an area that he/she knows contains a particular species
Advantages of opportunistic sampling
Easier and quicker then random sampling
Disadvantages of opportunistic sampling
Data may be biased
-The presence of large/ colourful species may entice the researcher to include that species
-May lead to an overestimate of its importance ad therefore an overestimate in biodiversity
Systematic sampling
When samples are taken at fixed intervals across the habitat
-Line transects and belt transects
Advantages of systematic sampling
Useful when the habitat shows a clear gradient in some environmental factor such as getting drier further from a pond
Disadvantages of Systematic sampling
Only species on the line/ within the belt can be recorded other species may be missed
-Over estimate in biodiversity
Preparation when sampling a habitat
-Suitable clothing
-Footwear
-Apparatus for sampling
-Clipboard, pen and paper for observations
-Appropriate keys to identify plants
-Camera/smartphone to record specimens and grid location
How are plants identified
Using a dichotomous key
Sampling plants
Large plants can be identified and counted individually
Many small plants - calculate a value of % ground cover by each species
Quadrat
A square frame is used to define the size of the sample area
-Identify plants then measure % cover
How can you measure the % cover of a species
Using a point frame
- 10 needles, used 10 times = 100 readings
- Each plant that touches = 1% cover
-Also make sure to account for bare ground
Transect
line taken across the habitat
-Samples taken along the line
Interrupted belt transect
Using a quadrat at set intervals along the transect
-Provides quantitive data at intervals across the habitat
Why is gaining quantitative data for animals difficult
-Not easy to spot
-Hide away
-Move too quickly for accurate counting
How can you estimate the population size of large animals
Looking for signs that they have left i.e. footprints/ droppings
-Owls deposit pellets of undigested food, rabbits have burrows, and deer damage the bark of trees in particular ways
-DNA sequencing to distinguish DNA droppings from different individals
Different methods of catching invertebrates
-Sweep net
-Pooter
-Hitting a branch against a branch after laying down a white sheet to dislodge any small animals
-Pitfall trap
-Tullgren funnel
-Light trap
Sweep net
1) Walk through the habitat with a stout net
2) Sweep the net through the vegetation in wide arcs
3) Small insects get caught in the net
4) Empty contents onto a white sheet to identify
-useful for low vegetayion that is not to woody
Pooter
Collect animals before fly away
Collecting from trees
Hitting a branch against a branch after laying down a white sheet to dislodge any small animals by the vibrations
-Quick to identify before fly away
Pitfall trap
Trap set in the soil to catch small animals
-Small container buried in the soil so the rim is just below the surface
-Animals moving through plants/leaf litter on the soil surface will fall into the container
-Trap should contain some water/scrunched-up paper to stop animals from crawling out
-Rainy weather plants should be sheltered from the rain so does not fill up
Tullgren funnel
Device for collecting small animals from leaf litter
-Place leaf litter in funnel
-Light above the litter drives the animal downwards as the litter dries and warms up
-Fall through a mesh screen to be collected into a jar underneath
Light trap
Collects flying insects at night
-Ultraviolet light that attracts the insects
-under light is a collecting vessel containing alcohol
-Moths/other insects attracted to light fall into alcohol
How are small animals trapped
Long worth trap
- Must be monitored regularly to release any trapped animals
- Population size - mark-recapture technique
Mark recapture
1) Capture a sample of animals
2) Mark individuals with non-toxic paint ( C1)
3) Release marked individuals and leave the traps for a period of time
4) Number captured on second occasion (C2) ones that are already marked (C3)
Mark - recapture formula
(C1 X C2) / C3
Disadvantages of longworth traps
Estimate calculated affected by animals that learn trap harmless and contains food
-Animals do not like experience so keep away
How are populations of birds est.
Ringing technique
Species richness
A measure of how many different species are present
Species evenness
A measure of how evenly represented the species are
How can species richness/evenness be measured?
Richness - counting
Evenness - quantitative survey
Way to measure species evenness
Plants - % cover
Large animals - counting
Small animals - mark-recapture
Water - use a net to sift through mud at bottom