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create resemblance matrices for all biotic variables. Statistical significance in ANOSIM
was tested based on 9,999 permutation runs. After a statistically significant main test, sig-
nificant pairwise comparisons between farming systems were further tested by similarity
percentage (SIMPER; Clarke and Gorley 2006) tests to identify individual variables that
were responsible for the observed differences. Two-dimensional nonmetric multidimen-
sional scaling (NMDS) was used as an ordination method to display significant results. All
NMDS ordinations were calculated with the Kruskal fit scheme 1, 150 restarts, and a sta-
bility criterion of 0.001. Variables on soil properties and ecosystem functions were normal-
ized by subtracting the variable's mean from all values and then dividing by the standard
deviation of the variable. Euclidean distances were used for these subsets of normalized
abiotic variables to create NMDS plots. To relate resemblance matrices of soil organisms
based on different taxonomic and functional group resolutions, soil properties, and eco-
system function data with each other, we calculated a new resemblance matrix based on
ρ (Spearman rank correlation) values of all pairwise comparisons between those matrices
and show this data in a second-stage NMDS plot (Clarke and Gorley 2006).
Table 5.2
provides an overview of the abundance and diversity of the studied soil and
surface-dwelling fauna in the DOK trial. None of the diversity indices was significantly
affected by farming system; for results on univariate abundance data, soil properties,
Table 5.2
Mean Abundance/Amount, Species/Genus Richness, Inverse Simpson Index, and
Pielou's Evenness for PLFAs, Nematodes, Enchytraeids, Spiders, and Carabids per Plot in Four
Replicated Wheat-Farming Systems
Mean
species/
genus
b
richness
Inverse
Simpson
diversity
(1 −
λ)
Mean
abundance/
amount
a
Pielou's
evenness
(J′)
Farming
system
Fatty acids (nmol g soil dw
−1
)
BIODYN
62
a
N/A
0.91
0.91
BIOORG
59
a
N/A
0.91
0.92
CONFYM
56
a
N/A
0.91
0.92
CONMIN
43
a
N/A
0.91
0.92
Nematoda (ind 100 g soil dw
−1
)
BIODYN
4966
27
b
0.87
0.72
BIOORG
5020
28
b
0.86
0.70
CONFYM
5008
30
b
0.89
0.73
CONMIN
2955
28
b
0.87
0.72
Enchytraeidae (ind m
−
²)
BIODYN
22,000
10
0.83
0.76
BIOORG
28,000
10
0.84
0.81
CONFYM
15,000
10
0.86
0.78
CONMIN
14,000
8
0.81
0.74
Araneae (ind m
−
²)
BIODYN
10
11
0.82
0.69
BIOORG
9
12
0.80
0.69
CONFYM
5
9
0.85
0.77
CONMIN
6
11
0.85
0.76
Carabidae (ind m
−
²)
BIODYN
8
10
0.85
0.78
BIOORG
7
11
0.86
0.80
CONFYM
5
9
0.79
0.77
CONMIN
6
9
0.81
0.79
Note:
For abbreviations and details, see
Table 5.1
.
(a) Amount for FAs, abundances for animals; (b) Nematodes
identified to genus level, all other species level.
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