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Environmental Science #1 > Research metods- popualtion studies > Flashcards

Research metods- popualtion studies Flashcards

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Biology 101 flashcards
1
Q

why are ecological surveys essential?

A

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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2
Q

what are some popualtion features that change over time?

A

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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3
Q

what are standard ecological techniques?

A

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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4
Q

what is a quadrat?

A

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

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5
Q

what can the results from multiple quadrats be used for?

A

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

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6
Q

how should you select quadrat size?

A

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

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7
Q

what are the typical quadrat sizes?

A

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

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8
Q

what types of quadrats are there?

A

open frame quadrat
grid quadrats
point quadrats

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9
Q

what is are open frame quadrats?

A

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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10
Q

what are grid quadrats?

A

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

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11
Q

what are point quadrats?

A

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

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12
Q

when are point quadrats used?

A

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

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13
Q

what is the problem with point quadrats?

A

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

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14
Q

what does a point quadrant look like?

A

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

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15
Q

what are the limitations of quadrats?

A

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

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16
Q

what are the methods for using pond nets?

A

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

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17
Q

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

A

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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18
Q

what are the limitations of using pond nets?

A

mobile species may escape

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19
Q

what does kick sampling do?

A

collects invertebrates that live on the river bed

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20
Q

what is the method for kick sampling?

A
  • 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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21
Q

what can be done to standardise kick sampling?

A

number and length of swings

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22
Q

what are the limitations of kick sampling?

A

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

23
Q

what is the positive of surber samplers over kick sampling?

A

provide a more standardised technique

24
Q

what is the method of a surber sampler?

A

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

25
Q

what are the limitations of surber samplers?

A

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

26
Q

what are sweep nets used for?

A

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

27
Q

what is the method for sweep nets?

A

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

28
Q

how can sweep nets be standardised?

A

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

29
Q

what are the limitations of sweep nets?

A

mobile species may escpae (flying insects)

30
Q

what are pitfall traps used for?

A

used to sample populations of mobile animals on the ground surface

31
Q

what is the method for pitfall traps?

A

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)

32
Q

what can be put in the bottom of pitfall traps?

A

a presevation fluid like antifreeze or ethanol

33
Q

what are the limiations of pitfall traps?

A

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

34
Q

what are beating trays used for?

A

to sample invertebrates present on vegetation above the ground

35
Q

what is the method beating trays?

A

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

36
Q

what are the limitations of beating trays?

A

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

37
Q

why are light traps used?

A

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

38
Q

what type of light is usaually used in light traps?

A

ultra violet lights

39
Q

what is the method for light traps?

A

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

40
Q

how can light traps be standardised?

A

the wavelength of bulb used
distace between traps

41
Q

what are the limitations of light traps?

A

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

42
Q

what are Tullgren funnels used for?

A

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

43
Q

what is the method for Tullgren funnel?

A

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

44
Q

what are the limitations of Tullgren funnels?

A

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

45
Q

what are suction sampler used for?

A

capture airborne insect o invertebrates that were dislodged from vegetation

46
Q

what do air suction sampler do?

A

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

47
Q

what do motor suction sampler do?

A

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

48
Q

what are pooters used for?

A

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

49
Q

what are the limitations of suction samplers?

A

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

50
Q

how are earthworms measured?

A

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

51
Q

what is the mustard powder earthworm method?

A

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

52
Q

what are the limitations of the mustard worm test?

A

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

53
Q

What are the assumptions when using the Lincoln index?

A

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

Environmental Science #1 (90 decks)

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