Slides in this set

Slide 1

Preview of page 1


Slide 2

Preview of page 2

· Ecology the study of inter-relationships between organisms and their
environment. Also it includes the study of life-supporting layer of land, air and
water that surrounds the Earth (biosphere).
· Ecosystem more or less self-contained functional unit in ecology made up of
all the interacting biotic and abiotic factors in a specific area
· Population a group of individuals of the same species that occupy the same
habitat at the same time.
· Populations of the same species form a community
· Community all the populations of different organisms living and interacting
in a particular place at the same time
· Habitat a place where a community of organisms live
· Within each habitat there are smaller units, each with their own microclimate.
These are called microhabitats
· Ecological niche all conditions and resources required for an organism to
survive, reproduce and maintain a viable population
· No two species occupy the same niche…read more

Slide 3

Preview of page 3

Investigating Populations: Quadrats
There are 3 factors to consider when using quadrats:
· The size of the quadrat depends on size of what's being counted and
how they're distributed within the area. Where a species occurs in a
series of groups rather than being evenly distributed throughout the
area, a large number of small quadrats will give more representative
results than a small number of large ones
· The number of sample quadrats to record he larger the number of
sample quadrats the more reliable the results will be. The recording of
species within an area is time-consuming, so there needs to be a balance
of validity of results and time available.
· The position of each quadrat to produce statistically significant
results, random sampling must be used.…read more

Slide 4

Preview of page 4

Random Sampling
· Sampling is random ­ avoids bias, ensures data obtained is valid
· Random sampling method:
· 1. Lay out two long tape measures at right angles, along two sides of the
study area
· 2. obtain a series of coordinates by using a random numbers taken from a
table or generated by a computer
· 3. Place a quadrat at the intersection of each pair of coordinates and record
the species within it…read more

Slide 5

Preview of page 5

Systematic Sampling (along transects)
· Can sometimes be more useful to measure the abundance and distribution
of a species rather than a random manner (particularly important where
some form of transition in the communities of plants/animals takes place)
· Stages of zonation are shown using transects
· A line transect consists of a string stretched across the ground in a straight
line. Any organism over which the line passes is recorded.
· A belt transect is a strip, marked by putting a second line parallel to the
first. The species occurring within between the lines is recorded.…read more

Slide 6

Preview of page 6

Measuring Abundance
· Random sampling with quadrats and counting along transects are used to obtain
measures of abundance
· Abundance the number of individuals of a species within a given space
· It can be measured by:
Frequency the likelihood of a particular species occurring in a quadrat. Gives a
quick idea of species present and their general distribution within an area. It does
not, however, provide information on the density and detailed distribution of a
Percentage Cover an estimate of the area within a quadrat that a particular
plant species covers. Data can be quickly obtained and individual plants do not
need to be counted. However, it is less useful when organisms occur in several
overlapping layers
· To obtain reliable results, a large sample size is needed, as many quadrats are
used and the mean of all the samples is obtained. The larger the number of
samples, the more representative of the community as a whole will be the
results…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9

Slide 10

Preview of page 10
Preview of page 10


No comments have yet been made

Similar Biology resources:

See all Biology resources »