ecological techniques

Question 1

deine the term ecology

Answer 1

the scientific sttudy of the factors which determine the distribution and abundance of organisms

Question 2

define the term population

Answer 2

all the individuals of one species in a habittat

Question 3

define the term community

Answer 3

all the organisms/ populations present in a habitat/ ecosystem

Question 4

define the term ecosystem

Answer 4

the community and the non living/ abiotic factors components of the environment

Question 5

give examples of abiotic factors

Answer 5

• co2
• o2
• water
• ph
• light intensity
• temperature
• shelter

Question 6

give examples of biotic factors

Answer 6

• competition
• predation
• symobioisi
• parasites

Question 7

define the term ecological niche

Answer 7

an organisms role in its ecosystem

Question 8

give the two ways in which the distribution of organisms can be measured

Answer 8

• randomly placed quadrats, or quadrats along a belt transect, for slow-moving or non-motile organisms
• the mark-release-recapture method for motile organisms.

Question 9

what can quadrats be used to measure?

Answer 9

• density
• frequency
• percentage cover

Question 10

when using a quadrat what two factors should be considered?

Answer 10

• the positioning

- the number of quadrats used

Question 11

why is random sampling used?

Answer 11

• avoid bias
• be representative
• produce statistically significant results

Question 12

how do we select the areas we sample in when using random sampling?

Answer 12

• random number generator

- random number table

Question 13

how doe the NE rule or equivalent help when using quadrats?

Answer 13

• avoids dealing with only parts of an organism
• avoids counting the same organism twice
• ensures consistency

Question 14

why does the sample size need to be large?

Answer 14

• so it is representative of the population

- so a statistical test can be carried out

Question 15

what is the minimum number of quadrats that should be taken?

Answer 15

20

Question 16

give a technique used to decide if the sample size is large enough

Answer 16

• running mean
• adding the new data collected from the quadrat to the previous quadrat
• when the mean no longer changes you will have collected a big enough sample

Question 17

describe measuring the frequency of a species

Answer 17

this is when you just record the presence or absence of a species in each quadrat

Question 18

describe measuring percentage cover

Answer 18

this is a measure of the proportion of the ground occupied by the species in the quadrat, as a percentage of the total area

Question 19

describe measuring the species density

Answer 19

counting the number of individuals of a species in a quadrat

Question 20

give the advantages of measuring the frequency of a species

Answer 20

quick and easy in large ecosystems

Question 21

give the advantages of measuring percentage cover

Answer 21

• quicker than counting

- useful when difficult to distinguish individual plants, and when one finishes an one starts

Question 22

give the advantages of measuring species density

Answer 22

-allows you to calculate an estimate of the population size can calculate species diversity

Question 23

give the disadvantages of measuring species density

Answer 23

• time consuming
• miss counts possible if in large numbers
• difficult to distinguish different plants

Question 24

give the disadvantages of measuring percentage cover

Answer 24

• it is subjective so estimates by different people will differ
• doesnt give an actual population size

Question 25

give the disadvantages of measuring the frequency of a species

Answer 25

- no estimate of population size - can give an inaccurate indication of relative abundance - results not detailed as one organism of a species counts the same as a 100 in a different sample

Question 26

what is a transect ?

Answer 26

taking a sample along a line

Question 27

wat is a transect used for ?

Answer 27

investigating how species distribution changes across and area

Question 28

which is more detailed a line transect or belt transect ?

Answer 28

belt transect

Question 29

Describe how you would collect data on the population of daisies in a field using random sampling

Answer 29

 tape measures to mark out a grid  random numbers, from tables or a calculator to generate coordinates  place quadrat and count all daisies in area – decide on rules for overlapping edges  repeat until you have a large sample/ do a running mean until it settles out  work out the mean number per quadrat and multiply by the number of quadrats in the area, or calculate the mean per m2 and multiply by the area in m2 .

Question 30

Describe how you would investigate how the distribution of plants changes from the middle to the edge of a woodland.

Answer 30

interrupted belt transect  could do more than one quadrat at each point to increase sample size and gain a more representative sample / reduce impact of anomalies / increase reliability  need regular measurements to be able to establish pattern/detect trends  estimate % cover / species frequency / species density  can convert to kite diagram

Question 31

what is the advantage of doing more than one quadrat at each point?

Answer 31

increase sample size and gain a more representative sample / reduce impact of anomalies / increase reliability

Question 32

describe the process of a line transect

Answer 32

A measuring tape is stretched across the habitat and plants are sampled at regular intervals, for example every 10cm. Each plant touching the line is identified and recorded.

Question 33

describe the process of a belt transect

Answer 33

Quadrats can be placed next to each other along a transect and estimates of the percentage cover or frequency of each species is recorded.

Question 34

what is a pitfall trap used for ?

Answer 34

crawling animals

Question 35

what trap catches crawling animals?

Answer 35

pitfall trap

Question 36

what trap catches water or sediment living organisms?

Answer 36

a kick sample net

Question 37

what is a kick sample net used for catching?

Answer 37

water or sediment living organisms

Question 38

what catches flying insects?

Answer 38

butterfly net

Question 39

what assumptions do we make when using the mark recapture release method?

Answer 39

- no immigration or emigration - no births or deaths - marking does not increase the likely hood of been recaptured or preyed upon - marked individuals have had a chance to mix fully back in with the population

Question 40

give the equation used when using the mark recapture release method

Answer 40

population number estimate= ( the number captured first x the number captured on second occasion) / the number recatured that were marked

Question 41

describe the method of mark release recapture

Answer 41

- using random sampling a large sample of organisms are caught - then the organisms are marked, counted and released back into the ecosystem - after release animals are given time to move around and thoroughly mix with the rest of the population - then again capture a large sample using the same technique as before - count the total number captured and the total number marked and then apply the equation

Question 42

when marking organisms what should you ensure?

Answer 42

the mark does not harm the animal or in any way affect their chance of survival