Cambridge International A Level Biology Revision Guide

Cambridge International A Level Biology
WORKED EXAMPLE 3
Drawing kite diagrams to display data on species
abundance
Some students used an interrupted belt transect to
investigate the distribution and abundance of seaweeds and
molluscs on a rocky shore placing a quadrat every 20 m. The
students began sampling at 20 m below mean sea level, when
the tide was out, and worked their way up the shore. They
used two different scales for assessing the abundance of
seaweeds and molluscs. On these scales, 5 indicates the
highest level of abundance and 1 the lowest. If a species is
not present in a quadrat it is obviously recorded as 0. The
table shows the data collected from an interrupted belt
transect on a rocky shore.
432
Distance
on the
shore / m
Seaweeds (algae)
Molluscs
Kelp
Serrated Bladder Spiral Dog Edible
wrack wrack wrack whelk periwinkle Limpet Flat
periwinkle
200 0 0 0 0 0 0 0 0 0
180 0 0 0 0 0 0 0 0 5
160 0 0 0 0 0 0 0 0 5
140 0 0 5 5 0 0 0 0 0
120 0 0 1 4 0 0 0 0 0
100 0 5 5 0 0 0 0 0 0
80 0 5 5 0 0 0 5 4 5
60 0 5 5 0 0 1 4 0 4
40 0 5 5 0 0 4 4 0 0
20 0 4 5 0 1 4 5 0 0
0 3 5 0 0 0 0 0 0 0
Rough
periwinkle
The data collected by the students is shown in the kite diagram in Figure 18.12.
200
180
160
140
Distance / m
120
100
80
60
40
mean
sea
level
20
0
kelp
serrated
wrack
bladder
wrack
spiral
wrack
dog whelk
edible
periwinkle
limpet
flat
periwinkle
rough
periwinkle
Figure 18.12 A kite diagram shows the data from a belt transect. The distribution of seaweeds and molluscs from low
tide to the top of the rocky shore is shown by the lengths of the ‘kites’ and the abundance by their widths. This gives a
representation of the ecosystem in a way that is easy to see.