Research metods- popualtion studies Flashcards by Andrew Jeavons

why are ecological surveys essential?

to find out which species are present
to moitor the habitat conditions (how they change, what conditions do they require)
monitor features of populations and how they change over time

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what are some popualtion features that change over time?

population size
age structure
growth rates
breeding rates
territory size
population movements
reliable, representative data are important in making good conservation management decisions

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what are standard ecological techniques?

include methods that work well and have been used for a long time often dating abck to beginnings of scientific ecology over 100 years ago

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what is a quadrat?

a study area usually sqaure, within which popualtions can be studied

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what can the results from multiple quadrats be used for?

can be scaled up to estimate the overall situation for the entire area

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how should you select quadrat size?

should be selected depends upon the habitat and groups of species being studied

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what are the typical quadrat sizes?

lichens: 10cmx10cm
ground flora: 0.5mx0.5m
trees in a forest: 100mx100m
bird survey: (presence not census): 10kmx10km

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what types of quadrats are there?

open frame quadrat
grid quadrats
point quadrats

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what is are open frame quadrats?

just amrk out an area
smaller ones may be made of plastic or metal
larger ones use reference refernce coordinatesmarked out by measuring tapes or gps corodinates

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what are grid quadrats?

sub-divided into smaller sqaures, for example, 10x10,each small sqaure represnets 1% of the area

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what are point quadrats?

used to collecg similar information to other quadrats but do not use a square area

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when are point quadrats used?

where ground flora is too tall for other quadrat types becuase it would be flattened and provide unrepresentative results

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what is the problem with point quadrats?

a % cover estimates would be inaccurate and shorter plants may be obscured by the flattened foilage of taller plants

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what does a point quadrant look like?

a wooden frame that supports 10 metal needles
each needle is 10%

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what are the limitations of quadrats?

subjective judgement may be involved (estimating % cover)
quadrat frame may flatten or move plants

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what are the methods for using pond nets?

can be swept through the water or aquatic vegetation to capture invertebrates, amphibians or fish

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what can be done to standardise the use of pond nets?

using particular length of sweep, or number of sweeps can be used in an attempt to standardise the method and produce comparable data

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what are the limitations of using pond nets?

mobile species may escape

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what does kick sampling do?

collects invertebrates that live on the river bed

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what is the method for kick sampling?

net is held with its straight edge on the river bed and its face open to the current
the river bed in front of the net is disturbed by repeadtly scarping your boot over it
## inverterbeates are dislodged and caught in the net

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what can be done to standardise kick sampling?

number and length of swings

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what are the limitations of kick sampling?

accurate standardisation is difficult
buried organisms or those fixed on stones may not be dislodged
some organisms can swim and avoid the net
water flow rate variable and affects the capture rate
fragile organisms may be destroyed

what is the positive of surber samplers over kick sampling?

provide a more standardised technique

what is the method of a surber sampler?

fixed area of river bed is sampled within a box like frame
riverbed is disturbed using a trowel or similat tool and stones inspected manually
netting at the sides of the net opening reduces the amount of organisms that escape

what are the limitations of surber samplers?

only be used where water flow is fast enough to carry organisms into the net samplers small size can make it difficult to set on rough substrates in deep water resulting in the loss of large organisms

what are sweep nets used for?

sturdy nets used to measure invertebrates in ground vegetation such as grassland

what is the method for sweep nets?

the net is swept through the vegetation so that organisms that are dislodged are caught (infinity symbol pattern to stop organisms escaping)

how can sweep nets be standardised?

Attempted by using the same number of sweeps of the same length

what are the limitations of sweep nets?

mobile species may escpae (flying insects)

what are pitfall traps used for?

used to sample populations of mobile animals on the ground surface

what is the method for pitfall traps?

container placed in a hole in the ground with its open end making a close fit with the soil and top level ground surface a cover is supported over the opening to keep away predators that might eat the caught organisms and prevent flooding by rain trap is checked over an agreed period (24hr)

what can be put in the bottom of pitfall traps?

a presevation fluid like antifreeze or ethanol

what are the limiations of pitfall traps?

only mobile species that live on the ground are caught more mobile species liekly to be cuaght trapped carnivores might kill other trapped organisms presevative fluid may attract or repel certain species some species avoid traps or can escape

what are beating trays used for?

to sample invertebrates present on vegetation above the ground

what is the method beating trays?

sheet or tray is placed beneath the vegetation which is beaten several times with a stick the invertebrates that are dislodged fall onto the sheet and are collected for identification and counting

what are the limitations of beating trays?

difficult to standardise method (force of htting the tree) some species not dislodged thicker branches shake less (organisms less likely to be dislodged) some species fly away and are not caught higher branches cannot be reached

why are light traps used?

used to collect night flying insects that are attracted by bright lights

what type of light is usaually used in light traps?

ultra violet lights

what is the method for light traps?

flying insects (moths) are attracted to the light and fall into a container container checked the following morning caught insects identified and counted

how can light traps be standardised?

the wavelength of bulb used distace between traps

what are the limitations of light traps?

moths only fly in the adult period + activity is affected by the weather (cold and wet) failure to find species doesn't mean they aren't present brightness and light wavelength emitted by light is more attractive to certain insects making it difficult to compare traps

what are Tullgren funnels used for?

used to sample mobile invertbrates in the leaf litter or the soil

what is the method for Tullgren funnel?

sample of soil or leaf litter placed on a mesh beneath a light light + heat repel some mobile invertebrates which move down through the mesh and fall into the container left for a standard period of time invertebrates identified and counted

what are the limitations of Tullgren funnels?

only species repelled by heat or light collected some organisms may die or stop moving some organisms too large to pass through mesh

what are suction sampler used for?

capture airborne insect o invertebrates that were dislodged from vegetation

what do air suction sampler do?

capture flying insects airflow rate can be measured and the cross sectional area of the collector tube is known then the number of insects per unit volume of air can be estimate

what do motor suction sampler do?

used to sample invertebrates on ground vegetation area of ground covered by suction pipe is known so popualtion density can be estimated

what are pooters used for?

sampler used o pick up invertebrates that have been found handling technique not populaiton sampling

what are the limitations of suction samplers?

some invertebrates may not be caught by air sampler may snese air sampler and fly away some insects may not be dislodged from vegetation by a suction sampler

how are earthworms measured?

difficult to observe so muct be removd form the soil for their popualtions to be monitored

what is the mustard powder earthworm method?

mark out sample area 0.5mx0.5m remove any vegetation that might block/hide worms add irritant (mustard) solution keep adding till the soil is saturated saturate surroundin area so the worms are less likely to move sideways add more as solution infiltrates soil collect womrs that come to the surface continue collecting worms until no more appear (standardised time period) count/measure/weigh/identify collected womrs

what are the limitations of the mustard worm test?

irritant solution may not percolate through the impermeable soil irritant solution may not reach the deepest worms worms may move sideways or down wroms may not move worms may die worms may move too slowly to be collection period

What are the assumptions when using the Lincoln index?

Proportion of marked to unmarked in 2nd sample same as whole population Marked individuals redistribute evenly No immigration/ emigration Few if any births/ deaths Marking used not toxic/can wear off Each individual has same chance of being caught in both samples