Chapter 1 - Núria BONADA

number of taxa
IASPT
35
30
25
20
15
10
5
0
0 100 200 300 400 500 600 700
7
6
5
4
individuals
3
0 100 200 300 400 500 600 700
individuals
G1
G2
G3
G4
c
G1
G2
G3
G4
IBMWP
160
120
80
40
individuals
Sampling protocol
a b
0
0 100 200 300 400 500 600 700
Figure 5. Number of taxa, accumulate IBMWP
and IASPT for each hundred of individuals and
for each working team.
The average values and the standard deviation of the number of taxa, IBMWP and IASPT
indices for all teams and habitats are presented in Figure 6. It can be observed a sharp
increase of the average values of each variable between the 100 and 200 individuals, although
standard deviations are quite high. No significant differences were found in any case between
the fractions of number of individuals counted (p=0.6912 for the number of families; p=0.7293
for the IBMWP and p=0.9788 for the IASPT). Consequently, a count of 100 individuals would
be enough to get an optimum number of individuals, a IBMWP and IASPT indexes,
respectively, although the high standard deviation present between groups.
45
G1
G2
G3
G4