Principal component analysis (PCA) with factors of distance and season both resulted in the first principal component (PC1) characterizing the land use gradient from agricultural (positive values) to forested (negative values) (Fig. 1). Increasing agricultural impact was positively correlated with higher soil temperatures and pH, and vegetation consisting of high forbs and tall grass and negatively correlated with shade, soil organic matter, and vegetation consisting coniferous trees, mosses, low forbs, short grass, and ferns (Fig. 1). PC2 with factors of distance characterized a gradient from the nearer the stream edge (negative values) of larger trees (> 20 cm width), smaller deciduous trees (0–2 cm width), shrubs, increasing shade, and increasing percentage of gravel and cobble substrates (Fig. 1a). PC2 with factors of season characterized a gradient from deciduous trees from 2–20 cm width, low forbs, and the percent sand/soil substrate (negative values) to increasing percent boulder and cobble substrate, large conifer trees (> 20.1 cm) and ferns (positive values) (Fig. 1b).
Ground beetles (Carabidae)
Affinity to aquatic insect subsidies
The mean correlation of ground beetle density and richness to aquatic insect abundance was positively associated with distance (significant intercept, est. 0.39, p = 0.0059; est. 0.43, p = 0.0001, respectively) (Table 2, Table 1 in Appendix A) and also analyses with season for richness (significant intercept, est. 0.25, p = 0.0350) (Table 2, Table 1 in Appendix A). Positive correlation between ground beetle richness and aquatic insect abundance increased with agricultural land use in microhabitats increasingly characterized by smaller substrate size, few deciduous trees, tall grasses and decreasing shade (significant interaction PC1*PC2 with factors of distance, est. 0.09, p = 0.0130) (Table 2, Fig. 1, Table 1 in Appendix A). Positive correlation between ground beetle density and aquatic insect abundance increased with agricultural land use in September (significant interaction PC1*September, est. 0.13, p = 0.0217) (Table 2, Table 1 in Appendix A). The proportion of ground beetle species richness to aquatic insect abundance increased in riparian habitats increasing associated with forested land use (significant PC1 with distance and season, est. -0.04, p = 0.0309; est. -0.02, p = 0.0353, respectively) (Table 2, Table 1 in Appendix A).
Potential consumption capacity
Table 2
Parameter estimates of GLMM results of ground beetle and aquatic insect abundance.
GROUND BEETLE DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.39
|
0.09
|
5.98
|
4.17
|
0.0059
|
Distance 1 m
|
0.25
|
0.13
|
11.00
|
1.96
|
0.0764
|
Distance 1 m*PC2
|
0.14
|
0.08
|
8.90
|
1.84
|
0.0989
|
Distance 10 m*PC2
|
-0.12
|
0.06
|
9.17
|
-1.99
|
0.0776
|
PC1*PC2
|
0.08
|
0.04
|
11.37
|
2.07
|
0.0623
|
Pearson R SEASON
|
Intercept
|
0.24
|
0.11
|
4
|
2.17
|
0.0959
|
September*PC1
|
0.13
|
0.05
|
8
|
2.84
|
0.0217
|
P/A DISTANCE
|
|
|
|
|
|
Intercept
|
0.41
|
0.07
|
6.35
|
5.66
|
0.0011
|
Distance 10 m*PC1
|
-0.04
|
0.02
|
7.62
|
-1.89
|
0.0972
|
PC1*PC2
|
0.04
|
0.01
|
8.30
|
2.51
|
0.0352
|
Distance 50 m*PC1*PC2
|
-0.02
|
0.01
|
8.28
|
-1.88
|
0.0955
|
P/A SEASON
|
Intercept
|
0.36
|
0.05
|
4
|
7.8
|
0.0015
|
GROUND BEETLES RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.43
|
0.06
|
8.50
|
6.66
|
0.0001
|
Distance 1 m*PC2
|
0.18
|
0.09
|
10.82
|
2.02
|
0.0691
|
PC1*PC2
|
0.09
|
0.03
|
6.96
|
3.31
|
0.0130
|
Pearson R SEASON
|
Intercept
|
0.25
|
0.08
|
4
|
3.14
|
0.0350
|
PC1*PC2
|
-0.03
|
0.01
|
4
|
-2.2
|
0.0930
|
P/A DISTANCE
|
Intercept
|
0.35
|
0.03
|
6.25
|
12.08
|
< .0001
|
PC1
|
-0.04
|
0.02
|
10.40
|
-2.49
|
0.0309
|
P/A SEASON
|
Intercept
|
0.27
|
0.02
|
4
|
14.34
|
0.0001
|
PC1
|
-0.02
|
0.01
|
4
|
-3.13
|
0.0353
|
Affinity to terrestrial dipteran abundance
Positive correlation between ground beetle density and terrestrial dipteran abundance increased with increase in agricultural land use (significant PC1 with distance and season, est. 0.13, p = 0.0106; est. 0.07, p = 0.042, respectively) (Table 3, Table 1 in Appendix B). At 1 meter distance the proportion of ground beetle density to terrestrial dipteran abundance was higher, and species richness to terrestrial dipteran abundance was lower (significant distance 1 m, est. 0.07, p = 0.0451; est. -0.18, p = 0.0317, respectively) (Table 3, Table 1 in Appendix B). The proportion of ground beetle density to terrestrial dipteran abundance increased in microhabitats increasingly characterized by smaller substrate size, few deciduous trees, tall grasses and decreasing shade (significant PC2, est. 0.04, p = 0.0411) (Table 3, Table 1 in Appendix B ). In April, the proportion of ground beetle density to terrestrial dipteran abundance was lower, and the proportion of ground beetle species richness to terrestrial dipteran abundance was higher (significant season April, est. -0.12, p = 0.0113; est. 0.14, p = 0.0079, respectively), while in July the proportion of ground beetle density to terrestrial dipteran abundance was higher, and the proportion of ground beetle species richness to terrestrial dipteran abundance was lower (significant season July, est. 0.11, p = 0.0173; est. -0.10, p = 0.0312, respectively) (Table 3, Table 1 in Appendix B). In July the proportion of ground beetle density to terrestrial dipteran abundance increased in riparian habitats increasingly associated with forested land use (significant interaction season July*PC1, est. -0.04, p = 0.0329) (Table 3, Table 1 in Appendix B).
Table 3
Parameter estimates of GLMM results of ground beetle and terrestrial dipteran abundance.
GROUND BEETLE DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
|
Intercept
|
-0.06
|
0.06
|
5.91
|
-1.05
|
0.3361
|
PC1
|
0.13
|
0.04
|
8.54
|
3.26
|
0.0106
|
Distance 10 m*PC2
|
-0.10
|
0.06
|
10.07
|
-1.83
|
0.0967
|
Pearson R SEASON
|
|
Intercept
|
-0.03
|
0.06
|
4.00
|
-0.56
|
0.6052
|
PC1
|
0.07
|
0.02
|
4.00
|
2.95
|
0.0420
|
P/A DISTANCE
|
|
Intercept
|
0.27
|
0.03
|
6.17
|
7.92
|
0.0002
|
Distance 1 m
|
0.07
|
0.03
|
10.64
|
2.27
|
0.0451
|
Distance 50 m
|
-0.06
|
0.03
|
10.27
|
-2.30
|
0.0437
|
PC2
|
0.04
|
0.02
|
11.70
|
2.30
|
0.0411
|
P/A SEASON
|
|
Intercept
|
0.25
|
0.05
|
4.00
|
5.23
|
0.0064
|
April
|
-0.12
|
0.04
|
8.00
|
-3.28
|
0.0113
|
July
|
0.11
|
0.04
|
8.00
|
2.99
|
0.0173
|
July*PC1
|
-0.04
|
0.01
|
8.00
|
-2.57
|
0.0329
|
GROUND BEETLE RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
|
Intercept
|
-0.08
|
0.10
|
5.72
|
-0.83
|
0.4397
|
Pearson R SEASON
|
|
Intercept
|
-0.05
|
0.06
|
4.00
|
-0.86
|
0.4370
|
P/A DISTANCE
|
|
Intercept
|
0.91
|
0.08
|
6.12
|
11.03
|
< .0001
|
Distance 1 m
|
-0.18
|
0.07
|
10.46
|
-2.48
|
0.0317
|
Distance 10 m
|
0.11
|
0.05
|
7.13
|
2.23
|
0.0603
|
Distance 1 m*PC1
|
-0.09
|
0.05
|
9.14
|
-1.90
|
0.0887
|
PC2
|
-0.09
|
0.05
|
11.90
|
-1.91
|
0.0800
|
P/A SEASON
|
|
Intercept
|
0.76
|
0.04
|
4.00
|
17.53
|
< .0001
|
April
|
0.14
|
0.04
|
8.00
|
3.52
|
0.0079
|
July
|
-0.10
|
0.04
|
8.00
|
-2.61
|
0.0312
|
Rove beetles (Staphylinidae)
Correlation and proportion to aquatic insect abundance
Positive correlation of rove beetle density and aquatic insect abundance increased in September in microhabitats increasingly characterized by fewer deciduous trees, decreasing percentage of shrubs, increased substrate sizes, and minimal shade (significant interaction season September*PC2, est. 0.10, p = 0.0163) (Table 4, Table 2 in Appendix A, Fig. 2). The proportion of rove beetle density and species richness to aquatic insect abundance increased in riparian habitats increasingly associated with forested land use in April (significant interaction season April* PC1, est. -0.27, p = 0.0165; est. -0.12, p = 0.0150, respectively) (Table 4, Table 2 in Appendix A, Fig. 2).
Table 4
Parameter estimates of GLMM results of rove beetle and aquatic insect abundance.
ROVE BEETLE DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.24
|
0.19
|
5.35
|
1.25
|
0.2646
|
Pearson R SEASON
|
Intercept
|
0.07
|
0.18
|
4
|
0.4
|
0.7126
|
April
|
0.14
|
0.07
|
8
|
1.93
|
0.0891
|
April*PC1
|
-0.06
|
0.03
|
8
|
-2.14
|
0.0647
|
September*PC2
|
0.10
|
0.03
|
8
|
3.03
|
0.0163
|
P/A DISTANCE
|
Intercept
|
0.47
|
0.04
|
4.91
|
11.07
|
0.0001
|
PC1
|
-0.06
|
0.03
|
7.85
|
-2.02
|
0.0782
|
P/A SEASON
|
Intercept
|
1.01
|
0.16
|
4
|
6.29
|
0.0033
|
April
|
0.71
|
0.23
|
8
|
3.1
|
0.0146
|
PC1
|
-0.25
|
0.06
|
4
|
-4.12
|
0.0146
|
April*PC1
|
-0.27
|
0.09
|
8
|
-3.02
|
0.0165
|
ROVE BEETLE RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.18
|
0.14
|
5.88
|
1.31
|
0.2378
|
Pearson R SEASON
|
Intercept
|
0.04
|
0.16
|
4
|
0.26
|
0.8044
|
P/A DISTANCE
|
Intercept
|
1.57
|
0.26
|
6.09
|
6.12
|
0.0008
|
Distance 10 m*PC1*PC2
|
-0.13
|
0.07
|
8.22
|
-1.91
|
0.0910
|
P/A SEASON
|
Intercept
|
0.53
|
0.05
|
4
|
10.02
|
0.0006
|
April
|
0.34
|
0.10
|
8
|
3.45
|
0.0088
|
July
|
-0.21
|
0.10
|
8
|
-2.07
|
0.0717
|
PC1
|
-0.11
|
0.02
|
4
|
-5.47
|
0.0054
|
April*PC1
|
-0.12
|
0.04
|
8
|
-3.09
|
0.0150
|
July*PC1
|
0.07
|
0.04
|
8
|
1.91
|
0.0932
|
Correlation and proportion to terrestrial dipteran abundance
Correlation of rove beetle density to terrestrial dipteran abundance was increasingly positive with increase in agricultural land use and increasingly negative with increase in forested land use (significant PC1 with distance, est. 0.13, p = 0.0343) (Table 5, Table 2 in Appendix B, Fig. 1). The proportion of rove beetle density to terrestrial dipteran abundance was greater in April (significant season April, est. 1.17, p = 0.0092) (Table 5, Table 2 in Appendix B).
Table 5
Parameter estimates of GLMM results of rove beetle and terrestrial dipteran abundance.
ROVE BEETLE DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.07
|
0.07
|
7.06
|
1.03
|
0.3363
|
Distance 10 m
|
-0.14
|
0.14
|
7.89
|
-1.04
|
0.3310
|
Distance 50 m
|
0.13
|
0.14
|
8.74
|
0.92
|
0.3798
|
PC1
|
0.13
|
0.05
|
7.91
|
2.55
|
0.0343
|
PC2
|
-0.09
|
0.03
|
2.48
|
-2.61
|
0.0973
|
Pearson R SEASON
|
Intercept
|
0.12
|
0.10
|
4.00
|
1.18
|
0.3021
|
P/A DISTANCE
|
Intercept
|
2.37
|
0.45
|
5.48
|
5.27
|
0.0025
|
Distance 10 m*PC2
|
-0.20
|
0.09
|
5.71
|
-2.22
|
0.0705
|
P/A SEASON
|
Intercept
|
3.34
|
0.70
|
4.00
|
4.77
|
0.0088
|
April
|
1.17
|
0.34
|
8.00
|
3.41
|
0.0092
|
September
|
-0.66
|
0.34
|
8.00
|
-1.94
|
0.0881
|
ROVE BEETLE RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
-0.01
|
0.09
|
5.27
|
-0.08
|
0.9407
|
Distance 10 m
|
-0.27
|
0.13
|
7.02
|
-2.03
|
0.0813
|
Distance 50 m
|
0.27
|
0.14
|
9.09
|
1.99
|
0.0780
|
PC1
|
0.08
|
0.06
|
8.21
|
1.29
|
0.2324
|
PC2
|
-0.06
|
0.06
|
3.61
|
-1.02
|
0.3722
|
Pearson R SEASON
|
Intercept
|
0.07
|
0.06
|
4.00
|
1.23
|
0.2849
|
P/A DISTANCE
|
Intercept
|
0.70
|
0.06
|
3.98
|
12.24
|
0.0003
|
Distance 10 m*PC2
|
0.02
|
0.03
|
7.10
|
0.52
|
0.6173
|
P/A SEASON
|
Intercept
|
0.57
|
0.03
|
4.00
|
19.36
|
< .0001
|
April
|
0.00
|
0.03
|
8.00
|
0.17
|
0.8689
|
September
|
0.04
|
0.03
|
8.00
|
1.59
|
0.1509
|
Sheet-web spiders (Linyphiidae)
Correlation and proportion to aquatic insect abundance
Positive correlation of sheet-web spider species richness to aquatic insect abundance at 1 m distance was observed and increased in riparian habitats associated with agricultural land use, while at 10 m distance positive correlation was observed and increased only in riparian habitats associated with forested land use (significant interaction distance 1*PC1, 10*PC1, est. 0.22, p = 0.0047; est. -0.17, p = 0.0053, respectively) (Table 6, Table 3 in Appendix A, Fig. 1). Positive correlation of sheet-web spider species richness to aquatic insect abundance at 10 m distance increased in microhabitats with greater number of deciduous trees, percent coverage of shrubs, and abundant shade (significant interaction between distance 10*PC2, est. -0.10, p = 0.0398) (Table 6, Table 3 in Appendix A, Fig. 1). The proportion of sheet-web spider density and species richness to aquatic insect abundance was greatest in April and increased in riparian habitats increasingly associated with forested land use (significant interaction season April*PC1, est. -0.11, p = 0.0133; est. -0.09, p = 0.004, respectively) (Table 6, Table 3 in Appendix A, Fig. 2).
Table 6
Parameter estimates of GLMM results of sheet-web spiders and aquatic insect abundance.
SHEET-WEB SPIDER DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
-0.35
|
0.11
|
1.73
|
-3.37
|
0.0954
|
Pearson R SEASON
|
Intercept
|
-0.04
|
0.07
|
4
|
-0.58
|
0.5926
|
P/A DISTANCE
|
Intercept
|
1.41
|
0.12
|
5.74
|
11.85
|
< .0001
|
Distance 50 m*PC2
|
-0.09
|
0.04
|
7.12
|
-1.95
|
0.0911
|
Distance 1 m*PC1*PC2
|
0.09
|
0.05
|
9.20
|
1.84
|
0.0985
|
P/A SEASON
|
Intercept
|
0.55
|
0.06
|
4
|
9.82
|
0.0006
|
April
|
0.50
|
0.09
|
8
|
5.43
|
0.0006
|
July
|
-0.24
|
0.09
|
8
|
-2.64
|
0.0299
|
September
|
-0.26
|
0.09
|
8
|
-2.8
|
0.0233
|
PC1
|
-0.08
|
0.02
|
4
|
-3.82
|
0.0188
|
April*PC1
|
-0.11
|
0.04
|
8
|
-3.17
|
0.0133
|
SHEET-WEB SPIDER RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
-0.15
|
0.07
|
5.83
|
-2.14
|
0.0777
|
Distance 1 m*PC1
|
0.22
|
0.06
|
11.04
|
3.53
|
0.0047
|
Distance 10 m*PC1
|
-0.17
|
0.05
|
10.03
|
-3.54
|
0.0053
|
Distance 1 m*PC2
|
0.11
|
0.05
|
8.71
|
2.01
|
0.0766
|
Distance 10 m*PC2
|
-0.10
|
0.04
|
8.88
|
-2.41
|
0.0398
|
Distance 10 m*PC1*PC2
|
-0.06
|
0.03
|
9.54
|
-2.01
|
0.0736
|
Pearson R SEASON
|
Intercept
|
0.02
|
0.11
|
4
|
0.15
|
0.8851
|
P/A DISTANCE
|
Intercept
|
0.57
|
0.06
|
2.78
|
8.79
|
0.0042
|
P/A SEASON
|
Intercept
|
0.39
|
0.03
|
4
|
11.81
|
0.0003
|
April
|
0.30
|
0.06
|
8
|
5.37
|
0.0007
|
July
|
-0.15
|
0.06
|
8
|
-2.58
|
0.0325
|
September
|
-0.16
|
0.06
|
8
|
-2.78
|
0.0238
|
PC1
|
-0.07
|
0.01
|
4
|
-5.16
|
0.0067
|
April*PC1
|
-0.09
|
0.02
|
8
|
-4
|
0.0040
|
July*PC1
|
0.05
|
0.02
|
8
|
2.22
|
0.0574
|
Correlation and proportion to terrestrial dipteran abundance
Negative correlation of sheet-web spider density to terrestrial dipteran abundance was observed in April (significant season April, est. -0.25, p = 0.0461) (Table 7, Table 3 in Appendix B). Positive correlation of sheet-web spider density to terrestrial dipteran abundance increased with increase in agricultural land use in September (significant interaction season September*PC1, est. 0.1, p = 0.039) (Table 7, Table 3 in Appendix B, Fig. 2). The proportion of sheet-web spider density to terrestrial dipteran abundance increased with increase in agricultural land use (significant PC1 with distance and season, est. 0.08, p = 0.038; est. 0.09, p = 0.0219, respectively) (Table 7, Table 3 in Appendix B, Fig. 2). The proportion of sheet-web spider species richness to terrestrial dipteran abundance decreased with increase in agricultural land use (significant PC1 with distance and season, est. -0.06, p = 0.0496; est. -0.02, p = 0.0458, respectively) (Table 7, Table 3 in Appendix B, Fig. 2). The proportion of sheet-web spider species richness to terrestrial dipteran abundance in April was increasingly lower in microhabitats associated with smaller substrate sizes, increased number of deciduous trees 2.1–20 cm, and higher percentage of low forbs (significant interaction season April*PC2, est. 0.03, p = 0.0105) (Table 7, Table 3 in Appendix B, Fig. 2). The proportion of sheet-web spider species richness to terrestrial dipteran abundance was greater in July and September (significant season July and September, est. 0.05, p = 0.0451; est. 0.05, p = 0.0356, respectively) (Table 7, Table 3 in Appendix B).
Table 7
Parameter estimates of GLMM results of sheet-web spiders and terrestrial dipteran abundance.
SHEET-WEB SPIDER DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.05
|
0.13
|
5.53
|
0.37
|
0.7257
|
PC1
|
-0.18
|
0.08
|
8.22
|
-2.25
|
0.0539
|
Distance 1 m*PC1*PC2
|
-0.17
|
0.09
|
10.60
|
-1.92
|
0.0818
|
Distance 10 m*PC1*PC2
|
0.13
|
0.06
|
9.76
|
2.17
|
0.0560
|
Pearson R SEASON
|
Intercept
|
0.11
|
0.06
|
4.00
|
1.85
|
0.1373
|
April
|
-0.25
|
0.11
|
8.00
|
-2.36
|
0.0461
|
September
|
0.24
|
0.11
|
8.00
|
2.21
|
0.0585
|
September*PC1
|
0.10
|
0.04
|
8.00
|
2.46
|
0.0390
|
PC2
|
0.08
|
0.03
|
4.00
|
2.68
|
0.0552
|
September*PC1*PC2
|
-0.04
|
0.02
|
8.00
|
-2.16
|
0.0623
|
P/A DISTANCE
|
Intercept
|
0.95
|
0.06
|
6.04
|
16.50
|
< .0001
|
PC1
|
0.08
|
0.03
|
8.54
|
2.45
|
0.0380
|
P/A SEASON
|
Intercept
|
1.11
|
0.06
|
4.00
|
17.48
|
< .0001
|
April
|
0.32
|
0.11
|
8.00
|
2.99
|
0.0173
|
September
|
-0.26
|
0.11
|
8.00
|
-2.48
|
0.0380
|
PC1
|
0.09
|
0.02
|
4.00
|
3.64
|
0.0219
|
SHEET-WEB SPIDER RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.20
|
0.13
|
5.27
|
1.46
|
0.2025
|
Pearson R SEASON
|
Intercept
|
0.21
|
0.08
|
4.00
|
2.73
|
0.0524
|
P/A DISTANCE
|
Intercept
|
0.89
|
0.04
|
5.79
|
20.82
|
< .0001
|
PC1
|
-0.06
|
0.03
|
8.31
|
-2.30
|
0.0496
|
P/A SEASON
|
Intercept
|
0.75
|
0.02
|
4.00
|
39.49
|
< .0001
|
April
|
-0.10
|
0.02
|
8.00
|
-4.90
|
0.0012
|
July
|
0.05
|
0.02
|
8.00
|
2.37
|
0.0451
|
September
|
0.05
|
0.02
|
8.00
|
2.52
|
0.0356
|
PC1
|
-0.02
|
0.01
|
4.00
|
-2.86
|
0.0458
|
April*PC2
|
0.03
|
0.01
|
8.00
|
3.32
|
0.0105
|
September*PC2
|
-0.02
|
0.01
|
8.00
|
-2.24
|
0.0551
|
Ground-hunting spiders (Lycosidae, Liocranidae, Zoridae, Corinnidae, Gnaphosidae)
Correlation and proportion to aquatic insect abundance
The mean correlation of ground-hunting spider density and richness to aquatic insect abundance was negative in analysis with factors of distance (significant intercept, est. -0.34, p = 0.0023; est. -0.34, p = 0.0177, respectively) (Table 8, Table 4 in Appendix A). Positive correlation of ground-hunting spider density to aquatic insect subsidies increased in agricultural land use in habitats with increasing substrate size and decreasing number of deciduous trees 2–20 cm width (significant interaction PC1*PC2, est. -0.01, p = 0.0339) (Table 8, Table 4 in Appendix A, Fig. 2). The proportion of ground-hunting spider density and species richness to aquatic insect abundance was highest in April and increased in riparian habitats increasingly associated with forested land use (significant interaction season April*PC1, est. -0.11, p = 0.022; est. -0.06, p = 0.0121, respectively) (Table 8, Table 4 in Appendix A, Fig. 2).
Table 8
Parameter estimates of GLMM results of ground-hunting spiders and aquatic insect abundance.
GROUND-HUNTING SPIDER DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
-0.34
|
0.07
|
7.28
|
-4.58
|
0.0023
|
Pearson R SEASON
|
Intercept
|
-0.02
|
0.00
|
1.00
|
-8.64
|
0.0733
|
PC1
|
0.03
|
0.00
|
1.00
|
43.69
|
0.0146
|
PC2
|
-0.05
|
0.00
|
1.00
|
-41.95
|
0.0151
|
PC1*PC2
|
-0.01
|
0.00
|
1.00
|
-18.76
|
0.0339
|
P/A DISTANCE
|
Intercept
|
0.52
|
0.09
|
5.29
|
5.57
|
0.0021
|
Distance 50 m
|
0.15
|
0.08
|
9.91
|
1.97
|
0.0775
|
P/A SEASON
|
Intercept
|
0.37
|
0.11
|
4.053
|
3.44
|
0.0256
|
April
|
0.41
|
0.10
|
5.297
|
4.19
|
0.0076
|
April*PC1
|
-0.11
|
0.03
|
5.105
|
-3.25
|
0.0220
|
GROUND-HUNTING SPIDER RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
-0.34
|
0.09
|
3.91
|
-3.94
|
0.0177
|
Pearson R SEASON
|
Intercept
|
-0.14
|
0.02
|
0.98
|
-6.95
|
0.0949
|
P/A DISTANCE
|
Intercept
|
0.60
|
0.08
|
5.31
|
7.34
|
0.0006
|
P/A SEASON
|
Intercept
|
0.25
|
0.05
|
4.226
|
4.93
|
0.0068
|
April
|
0.23
|
0.05
|
5.552
|
4.82
|
0.0036
|
July
|
-0.13
|
0.06
|
5.608
|
-2.36
|
0.0596
|
September
|
-0.10
|
0.05
|
5.29
|
-2.05
|
0.0929
|
PC1
|
-0.05
|
0.02
|
3.742
|
-3.02
|
0.0428
|
April*PC1
|
-0.06
|
0.02
|
5.356
|
-3.72
|
0.0121
|
Correlation and proportion to terrestrial dipteran abundance
No significant correlations were detected between ground-hunting spiders and terrestrial dipteran abundance. The proportion of ground-hunting spider density to terrestrial dipteran abundance was greater with increasing forested land use in April (significant interaction season April*PC1, est. -0.04, p = 0.0283) (Table 4 in Appendix B, Fig. 2). The proportion of ground-hunting spider density to terrestrial dipteran abundance was lower in September (significant season September, est. -0.10, p = 0.0407) (Table 4 in Appendix B). The proportion of ground-hunting spider species richness to terrestrial dipteran abundance was lower in April (significant season April, est. -0.11, p = 0.0245) (Table 4 in Appendix B).
Table 9
Parameter estimates of GLMM results of ground-hunting spiders and terrestrial dipteran abundance.
GROUND-HUNTING SPIDER DENSITY
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.14
|
0.17
|
5.94
|
0.79
|
0.4617
|
Distance 10 m
|
-0.22
|
0.11
|
6.34
|
-2.00
|
0.0901
|
Pearson R SEASON
|
Intercept
|
0.00
|
0.18
|
3.37
|
-0.01
|
0.9892
|
April*PC2
|
0.17
|
0.07
|
4.49
|
2.42
|
0.0656
|
July*PC2
|
-0.16
|
0.07
|
4.17
|
-2.22
|
0.0879
|
P/A DISTANCE
|
Intercept
|
0.62
|
0.11
|
5.79
|
5.48
|
0.0017
|
Distance 50 m*PC2
|
0.09
|
0.05
|
7.33
|
2.08
|
0.0747
|
P/A SEASON
|
Intercept
|
0.84
|
0.13
|
4.02
|
6.23
|
0.0033
|
April
|
0.15
|
0.03
|
4.08
|
4.48
|
0.0105
|
September
|
-0.10
|
0.03
|
4.05
|
-2.96
|
0.0407
|
April*PC1
|
-0.04
|
0.01
|
4.07
|
-3.34
|
0.0283
|
GROUND-HUNTING SPIDER RICHNESS
|
Estimate
|
Std Error
|
DFDen
|
t Ratio
|
Prob>|t|
|
Pearson R DISTANCE
|
Intercept
|
0.05
|
0.16
|
5.65
|
0.32
|
0.7617
|
Pearson R SEASON
|
Intercept
|
-0.03
|
0.17
|
2.48
|
-0.18
|
0.8720
|
April*PC2
|
0.18
|
0.07
|
3.74
|
2.56
|
0.0667
|
P/A DISTANCE
|
Intercept
|
1.11
|
0.15
|
6.20
|
7.53
|
0.0002
|
P/A SEASON
|
Intercept
|
0.79
|
0.06
|
3.92
|
14.08
|
0.0002
|
April
|
-0.11
|
0.03
|
4.36
|
-3.37
|
0.0245
|