2.5 - Investigating Ecosystems Flashcards
Name 2 ecosystems
- amazon rainforest, South America
- Serengeti, Tanzania
How do you identify organisms in a ecosystem
- comparison to herbarium or specs in collections
- technologies such as DNA profiling
- scientific expertise
- dichotomous keys
How do you identity a organisms through comparison to herbarium or specimen collections
Herbariums and specimen collections are archives of pressed and preserved plants, animals, and other organisms
These collections can be used to compare the characteristics of the organisms in question with the archived specimens to identify them
How do you identify a organism in a ecosystem through technologies such as DNA profiling
DNA profiling involves the extraction of DNA from an organism, which is then amplified and sequenced
The resulting sequence can be compared to known sequences in databases to identify the organism
How do you identify a organism through scientific expertise
Scientists with specialised knowledge of a particular group of organisms can identify them based on their morphology, anatomy, and behaviour
How do you identify a organism through dichotomous keys
Dichotomous keys are tools used to identify organisms based on their characteristics
The keys consist of a series of questions with two possible answers, leading to the identification of the organism
What are 6 limitations of dichotomous keys
- limited scope
- Inaccuracies
- Variability
- Time consuming
- Expertise required
- Limited physical characteristic
What are 8 ways of measuring the abiotic components of a ecosystem
- light intensity
- temperature
- wind speed
- disolved oxygen
- flow velocity
- turbidity
- PH
- soil moisture
How do you measure light intensity and what are the strength and limitations
- light meter
Pros : quick and easy to use, non invasive, accurate and precise measurement if direction and angle of use is consistent over repeats
Cons : can only measure a single point, doesn’t measure spectral quality or light direction, affected by shading, cloud cover and atmospheric conditions
How do you measure temperature and what are the strength and limitations
- thermometer
Pros : Simple and easy to use, highly accurate if using an electronic thermometer (temperature probe), which can measure temperature of air, water and varying soil depths
Cons: Can only measure at a single point, doesn’t measure temperature fluctuations over time (unless used alongside a datalogger)
How do you measure wind speed and what are the strength and limitations
- anemometer
Pros : Quick and easy to use, non-invasive, accurate and precise measurement if direction and angle of use is consistent over repeats
Cons : Gusty conditions can lead to large variations in data
How do you measure disolved oxygen and what are the pros and cons
- oxygen meter
Pros : Can measure changes over time if used alongside a datalogger
Cons : Can be expensive and require calibration, can be affected by temperature and salinity, or contaminated by oxygen in air if correct procedure not followed
How do you measure flow velocity and what are the pros and cons
- flow meter
Pros : Provides accurate measurements and can be attached to a datalogger
Cons : Water flow can fluctuate greatly due to rainfall or ice melt, can be affected by turbulence or eddies
How do you measure turbidity and what are the pros and cons
- secchi disc
Pros : More accurate if used in shady areas of water
Cons: Sun glare and reflections reduce visibility of disc, measurements are subjective, alternative more sophisticated optical equipment (e.g. nephelometer or turbidimeter
How do you measure PH and what are the pros and cons
- PH probe or meter
Pros : soil PH can also be measured using a soil testing kit
Cons: requires calibration, affected by shrouding enviroment
Hope do you measure soil moisture and what are the pros and cons
- evaporate water or soil moisture probe
Pros: fairly inexpensive
Cons: Time consuming, organic soil content may be burned off during heating, reducing soil weight and giving inaccurate readings
What are the problems with measuring the levels of biodiversity
Measuring all the different levels of biodiversity within an ecosystem could be very time-consuming
Finding out which species live in an ecosystem and the size of the populations requires the identification and cataloguing of all organisms present to build a species list
What are the steps to measure levels of biodiversity using a quadrant
- Placing quadrat down
- Estimating population size
- Estimating percentage frequency and percentage cover
What can quadrants be used to measure
- The number of an individual species: the total number of individuals of a single species (eg. daisies) is recorded
- Species richness: the total number of different species (but not the number of individuals of each species) is recorded
- Percentage cover: the approximate percentage of the quadrat area in which an individual species is found is recorded (this method is often used when it is difficult to count individuals of the plant species being recorded eg. grass or moss)
Where just quadrats be laid
Quadrats must be laid randomly in the area to avoid sampling bias
This random sampling can be done by converting the sampling area into a grid format and labelling each square on the grid with a number
Then a random number generator is used to pick the sample points
What happens once the quadrat has been laid
The abundance of different species can be recorded
What are the steps to estimating population size
- Use 2 tape measures to lay a survey area
- Use random number generator to create set of coordinates to place your first quadrant
- Count number of chosen plant species in the quadrat
- Record this number in table and repeat process 10 time
- Estimate population of dandelions using the equation
Estimated population size = total area/ area sampled x total number of dandelions counted
What can the results from the quadrant be used to calculate
The predicted frequency and density of species within a area
What is species frequency
The probability that the species will be found within any quadrant or sample area
- the number of quadrats that the species was present in is divided by the total number of quadrants then times by 100
Define species density
Species density indicates how many individuals of that species there are per unit area
- The number of individuals counted across all quadrats is divided by the total area of all the quadrats
What happens when it’s difficult to count individual plants of organisms
When this is the case percentage cover of the species within the quadrat can be estimated instead
The quadrat is divided into 100 smaller squares. The number of squares the species is found in is equivalent to its percentage cover in that quadrat
What are the limitations of using a quadrat
It can be easy to miss an organism when counting in the quadrat, specially when they are covered by other species.
Identifying species might be difficult
What methods do you use for counting the abundance of motile organisms
- Sweeping nets
- Pitfall traps
- Posters
- Tullgren funnel
- Kick sampling
What is a sweeping net
these are large, strong nets with a fine material (very small holes) that are used to catch flying insects and insects that live in long grass by sweeping the net back and forth through the grass
What are pitfall traps
these are cans or jars that are buried in the ground that are used to catch ground-dwelling (often nocturnal) insects and other invertebrates as they fall into the trap
What are pooters
these are small plastic or glass containers with two tubes sticking out that are used to suck up small insects and other small invertebrates. The first tube is placed over the insect and the second tube is used by the scientist to create suction
What are tullgren funnels
these are funnels with a light bulb above and a container below that are used to collect invertebrates that live in leaf litter or soil. The leaf litter or soil is placed in the funnel and the light and heat forces the invertebrates to move down until they drop into the container
What is kick sampling
this technique is used to catch freshwater invertebrates living in streams or rivers. A net in placed on the stream-bed so that the water is flowing into it and the stream-bed just above the net is churned up by the scientist (using their foot) for a set period of time. The invertebrates are carried by the stream into the net
What is a indirect method for estimating abundance of motile organisms
Mark - release - recapture
(Lincoln index)
What is the Lincoln index best for
Motile organisms
What are the steps of the mark capture release method
- The first sample is taken and they are counted and marked in a way which wont affect their survival
- The marked individuals are returned to habitat and all waged to randomly mix with rest of population
- When time has past they are recaptured
- The number of marked and unmarked are counted
- The proportion of marked to unmarked is used to calculate population size
- Number are put into Lincoln index formula
What is the Lincoln index formula
= n1 x n2 / nm
N1= number caught first sample
N2 = number caught second sample
Nm = number of marked individuals in the second sample
What are the limitations of using the mark - release and recapture method
- you have to wait for sufficient time
- population size might change
- markings might rub off
What is species richness
The number of species in a community or defined area that can be useful comparative measure
Species richness v diversity
A measurement that describes the relationship between number of species present and hope each species contributes to the total number of organisms that are present in that community
What is used to calculate species richness v diversity
Simpsons index
What is the formula for Simpson’s index
D = n(n-1)/ zigma n (n-1)
LOOK AT HOW TO DO SIMPSON INDEX
What are the methods for measuring biomass and energy
- measurement of dry mass
- controlled combustion
- extrapolation for samples
How do you measure dry mass and what does it estimate
It estimates the levels of biomass
- it involves collecting samples of organisms and drying them in a oven to remove water within a tissue
- the dry weight of the samples is then measured, and this can be used to estimate the biomass of the population
What is controlled combustion a nd what is it used for
It estimates biomass
- this involves burning a known quantity of biomass and measuring the heat produced by
- by knowing the value of biomass, its possible to estimate the total biomass and population based on amount of heat produced
- its carried out in a calorimeter
How do you extrapolate a sample
This is used to estimate biomass
- it takes small samples of organism and extrapolates then to estimate the total biomass of a population
- data obtained from these methods can be used to construct ecological footprints
What are some limitations of calorimetry
- it can take a long time to fully dehydrate
- precise equipment is needed, which may not be available
- the more simple and basic the calorimeter the less accurate the estimate will be for the chemical energy contained within the plant sample.
What are the 2 types of sampling
- random an
- systematic
What is a transect used for
- Systematic sampling is used when there is a clear change in the physical conditions across the area being studied
- For example, there may be changes in altitude, soil pH or light intensity
- Methods using transects can help show how species distribution changes with the different physical conditions in the area
- A transect is a line represented by a measuring tape, along which sample are taken
What are the 2 types of transects
- line transect = when you lay a measuring tape in a straight line across the sample area, then at equal distances along the tape record the identity of the organism that touches the line
- belt transect = place quadrat at regular intervals along the tape and record the abundance or percentage cover of each species within the quadrat
How do you represent the results from a transect
Kite diagram
