L.J. Cole et al. Agriculture, Ecosystems and Environment 83 2001 177–189 181
‘splitter’, separating Collembola into species on the basis of very small differences in morphology Hop-
kin, 1997, the information derived from this study was maximised.
2.3. Statistical analysis The five samples collected from each plot on a sam-
pling date were pooled to obtain an indication of over- all collembolan community structure for each plot on
each specific sampling date. The pooled data were used in statistical analyses and the pitfall and suction
data sets were investigated separately.
Prior to analyses, the variance to mean ratios were calculated to determine if species abundances were
normally distributed. For the majority of species it was found that the variance and means were about equal
indicating that the distribution was random Sokal and Rohlf, 1995. Square-root transformation was, there-
fore, more appropriate and effective at normalising the data than the more common log transformation. It
was deemed inappropriate to use different transforma- tions for different species, and consequently the abun-
dance of all species was square-root transformed. It was, however, recognised that even after transforma-
tion the variances for some species were still hetero- geneous and, consequently, the significance value was
Table 3 Results of ANOVAs and Tukey tests performed on Collembola species obtained by suction sampling at SAC Auchincruive
a
Species Date
Treatment F-value
Probability Location of difference
F-value Probability
Location of difference Total
20.04 0.001
May and JunApr, MayAug 5.17
0.01 UC
Isotoma viridis 20.91
0.001 AugAll
16.75 0.001
AllCd Isotoma notabilis
7.29 0.001
MayJun 2.12
N.S. –
Isotoma anglicana 129.75
0.001 MayApr and AugJun
24.14 0.001
AllC Isotomurus palustris
86.70 0.001
MayJunAug and Apr 12.51
0.001 Zn and CdC
Isotomurus maculatus 24.80
0.001 MayApr and JunAug
4.76 0.01
UC IsotomaIsotomurus juvenile
56.36 0.001
MayJun and AprAug 2.66
N.S. –
Lepidocyrtus cyaneus 5.01
0.01 AugApr
15.77 0.001
AllCd Heteromurus nitidis
8.12 0.001
AugAll 8.12
0.001 UC
Tomocerus longicornis 13.34
0.001 AugApr and May, JunApr
1.34 N.S.
– Sminthurus viridis
4.60 0.01
JunApr 23.15
0.001 CAll CdU and Zn
Sminthurinus aureus 27.22
0.001 May and JunAprAug
2.48 N.S.
– Sminthurides malmgreni
13.91 0.001
AprAll 1.89
N.S. –
Ceratophysella denticulata 31.76
0.001 Apr and MayJun and Aug
6.08 0.01
ZnC
a
As no block effect was found for any of the species tested, this information is omitted from the table. The following codes are used for treatments: C, control; U, uncontaminated sludge; Zn, zinc-rich sludge; and Cd, cadmium-rich sludge.
set at 0.01 to avoid wrongly rejecting the null hypoth- esis Day and Quinn, 1989.
Effects of date, treatment and block were tested for using three-way analyses of variance without
replication. Examination of the data prior to analysis indicated that interaction did not occur and it was,
therefore, possible to perform the tests without repli- cation hence enabling block effects to be investigated.
For each dataset, separate ANOVAs were performed on the abundance of total Collembola and on fre-
quently occurring species i.e. those occurring in over 50 of samples. Tukey multiple comparison tests
were then applied to locate significant differences identified by ANOVA.
3. Results
Suction sampling collected a total of 122,323 indi- viduals from 22 species and pitfall trapping collected
44,745 individuals from 20 species. Of these species, 13 occurred frequently enough to allow statistical
analysis at the species level Tables 3 and 4. Ju- venile Isotoma and Isotomurus species cannot be
identified accurately to species level and were there- fore grouped together and treated as one of the 13
species in the analyses. It is interesting to note that the following species occurred at too low a frequency
182 L.J. Cole et al. Agriculture, Ecosystems and Environment 83 2001 177–189
Table 4 Results of ANOVAs and Tukey tests performed on Collembola species obtained from pitfall trapping at SAC Auchincruive
a
Species Date
Treatment F-value
Probability Location of difference
F-value Probability
Location of difference Total
7.58 0.001
AllApr 6.14
0.01 UCd
Isotoma viridis 12.14
0.001 AugAll
8.97 0.001
UCd Isotoma notabilis
7.85 0.001
AprAll 4.51
0.01 UC
Isotoma anglicana 62.93
0.001 MayJun and AugApr
3.47 N.S.
– Isotomurus palustris
25.28 0.001
AllApr 6.32
0.01 AllC
Isotomurus maculatus 17.87
0.001 May and AprAug, MayJun
8.76 0.001
UC and Cd IsotomaIsotomurus juvenile
31.12 0.001
AllAug, MayApr 12.61
0.001 AllC
Lepidocyrtus cyaneus 5.83
0.01 AugApr and May
10.60 0.001
C and UCd Heteromurus nitidis
7.65 0.001
AugApr and May 4.21
0.01 UC
Sminthurus viridis. 0.39
N.S. –
3.99 N.S.
– Sminthurinus aureus
23.72 0.001
May and JunApr, JunAug 1.39
N.S. –
Sminthurinus elegans 0.97
N.S. –
1.40 N.S.
– Sminthurides pumilis
17.95 0.001
AugustAll 0.78
N.S. –
Ceratophysella denticulata 1.21
N.S. –
4.56 0.01
ZnCd
a
As no block effect was found for any of the species tested, this information is omitted from the table. The following codes are used for treatments: C, control; U, uncontaminated sludge; Zn, zinc-rich sludge; and Cd, cadmium-rich sludge.
to merit separate statistical analysis: F. candida, F. fimetarioides Axelson, I. tigrina Nicoleti, Entomo-
brya nivalis Linné, Lepidocyrtus lignorum Fabrici- cus, Pseudosinella decipiens Denis, Tomocerus minor
Lubbock, Dicyrtoma saundersi Lubbock, Dicyr- toma ornata Nicolet and Anurida pygmea Börner.
Results of the ANOVAs for the suction data are presented in Table 3 and for the pitfall data in
Table 4. While no block effect was found for any of the species investigated, effects of treatment and date
were apparent.
3.1. Seasonal variation indicated by suction sampling The influence of season on collembolan abun-
dance was species-specific. The abundance of total Collembola, IsotomurusIsotoma juveniles, Isoto-
murus palustris Müller and Isotomurus maculatus Schaeffer increased from April to May, reaching
Table 5 Mean grass height in cm in experimental plots for each treatment and sampling date showing standard deviations in brackets
Control Uncontaminated
Zinc-rich Cadmium-rich
April 13.0 ±2.02
31.5 ±3.76 30.7 ±3.32
27.1 ±3.54 May
10.9 ±2.74 10.1 ±2.91
10.1 ±2.05 9.2 ±2.19
June 16.7 ±3.18
43.0 ±8.06 43.7 ±4.10
39.2 ±5.14 August
9.1 ±1.61 7.4 ±1.77
7.7 ±2.67 8.5 ±2.87
their peak in May suction samples, before decreasing again in August Table 3. Tomocerus longicornis,
Lepidocyrtus cyaneus Tullberg, Heteromurus ni- tidis Templeton and I. viridis Bourlet increased
as the summer progressed, occurring in their high- est abundance in August suction samples Table 3.
Ceratophysella denticulata Bagnall was more abun- dant in April and May than in June or August and
Sminthurides malmgreni Tullberg occurred almost exclusively in April samples Table 3. I. anglicana
occurred in its lowest abundance in June when the grass was longest, while Sminthurus viridis Linné
occurred in its highest Tables 3 and 5.
3.2. Seasonal variation indicated by pitfall trapping Isotoma viridis, Sminthurides pumilis Krausbauer,
H. nitidis and L. cyaneus occurred in their highest abundance in August pitfalls Table 4. With the
L.J. Cole et al. Agriculture, Ecosystems and Environment 83 2001 177–189 183
Fig. 1. Effect of sludge treatment on the abundance of total Collembola, Heteromurus nitidis and Isotomurus maculatus caught by suction sampling showing mean number square-root transformed. Error bars show standard deviations.
exception of S. pumilis, which did not occur in suction samples in sufficient numbers for statistical analysis
to be applied, these species were also more abundant in August suction samples. In agreement with the
suction sample results, IsotomaIsotomurus juveniles peaked in May pitfalls Table 4. Isotoma notabilis
was significantly more abundant in April pitfalls than on any other sampling date Table 4. As the higher
abundance in April pitfalls was not replicated in suc- tion samples, it is possible that it was a consequence
of an increase in activity due to the digging in effect Joosse and Kapteijn, 1968.
3.3. Treatment effects indicated by suction sampling The addition of uncontaminated sludge significantly
increased the abundance of H. nitidis, I. maculatus and total Collembola above that of the control plots
Table 3 and Fig. 1. This increase was not significant in plots receiving contaminated sludge i.e. zinc and
cadmium-rich sludge, hence, indicating adverse ef- fects of the metal-rich sludges. Cadmium-rich sludge
was clearly shown to adversely affect L. cyaneus and I. viridis and both species occurred in their lowest
abundance in plots receiving this sludge Table 3 and Fig. 2. Isotomurus palustris was significantly more
abundant in plots receiving contaminated sludge but not uncontaminated sludge than control plots Table 3
and Fig. 3, while C. denticulata was significantly more abundant in plots receiving zinc-rich sludge than
control plots Table 3 and Fig. 4. Isotoma anglicana was favoured in all plots receiving sludge irrespective
of metal contamination Table 3 and Fig. 3.
Sminthurus viridis was the only species to occur in its highest abundance in control plots, and this species
was also significantly more abundant in plots receiv- ing cadmium-rich sludge than those receiving uncon-
taminated or zinc-rich sludge Table 3 and Fig. 4.
3.4. Effects of treatment indicated by pitfall trapping Pitfall trapping also indicated that cadmium-rich
sludge adversely affected I. viridis and L. cyaneus and a significantly lower number of both species occurred
in pitfalls set in plots receiving cadmium-rich sludge than those in plots receiving uncontaminated sludge
Table 4 and Fig. 5. Furthermore, the abundance of L. cyaneus in plots receiving cadmium-rich sludge was
significantly lower than that of control plots.
Pitfall trapping indicated that numbers of I. nota- bilis, I. maculatus and H. nitidis were significantly
higher in plots receiving uncontaminated sludge than control plots, again indicating adverse effects of con-
taminated sludge Table 4 and Fig. 6. Furthermore,
184 L.J. Cole et al. Agriculture, Ecosystems and Environment 83 2001 177–189
Fig. 2. Effect of sludge treatment on the abundance of Isotoma viridis and Lepidocyrtus cyaneus caught by suction sampling showing mean number square-root transformed. Error bars show standard deviations.
the total collembolan abundance and the abundance of I. maculatus was significantly lower in pitfalls es-
tablished in plots receiving cadmium-rich sludge than in those receiving uncontaminated sludge Table 4,
Figs. 5 and 6. This difference was not significant in the suction sampling results Table 3.
IsotomaIsotomurus juveniles and I. palustris had a significantly higher abundance in pitfalls placed in
plots receiving sludge than those placed in control plots Table 4 and Fig. 7. In agreement with the
suction results, C. denticulata occurred in its high-
Fig. 3. Effect of sludge treatment on the abundance of Isotoma anglicana and Isotomurus palustris caught by suction sampling showing mean number square-root transformed. Error bars show standard deviations.
est abundance in pitfalls established in plots receiving zinc-rich sludge Table 4 and Fig. 7.
4. Discussion
