Ecological Archives E095-085-A1

S. Braaker, J. Ghazoul, M. K. Obrist, M. Moretti. 2014. Habitat connectivity shapes urban arthropod communities: the key role of green roofs. Ecology 95:1010–1021. http://dx.doi.org/10.1890/13-0705.1

Appendix A. Tables showing the number and proportion of species captured on roofs and the ground and the results of the redundancy analysis (RDA) and variation partitioning analyses.

Table A1. Number of species and proportion of total species per taxon, in brackets, captured on 40 roof sites and 38 ground sites. The columns list: species occurring exclusively on roof sites, exclusively on ground sites, on both roof and ground sites and the total number of captured species.

Taxon

Roof exclusive

Ground exclusive

Roof+ground

Total

Carabids

5 (7%)

27 (38%)

40 (56%)

72

Spiders

34 (21%)

46 (28%)

83 (52%)

163

Weevils

18 (15%)

37 (31%)

63 (53%)

118

Bees

11 (9%)

49 (39%)

67 (52%)

127

 

Table A2. Results of redundancy analyses (RDA) and subsequent variance partitioning for different arthropod communities. Each row shows the variance explained by pure and joint fractions of local (Loc), land-cover (Land) and connectivity (Con) variables, unexplained variance (Residuals) and total variance explained by all fractions (Total var. expl.). Symbols of fractions, in squared brackets, are visualized in the overall scheme of the analyses in Fig 1. Analyses are performed separately for each arthropod community (carabids, spiders, weevils, bees on roof, ground, and roof+ground, respectively). Percentages of variance explained by pure and joint fractions are given as R² adjusted (R²adj). Asterisks indicate significance levels of pure fractions (* = p < 0.05, ** p < 0.01). Example: For carabid roof community composition the joint fraction of land-cover and connectivity (Land_Con) explained 1.64% of total variance.

 

 

Variance explained for the four arthropod groups

 

Fractions

Symbols

Carabids (%)

Spiders (%)

Weevils (%)

Bees (%)

Roof community

Loc

[a]

6.47 **

8.82 **

0.04

-

Land

[b]

2.14 *

2.54 *

0.27

3.01 *

Con

[c]

2.05

4.22 **

4.55 **

8.38 **

Loc_Land

[a+b]

-

-

-

-

Land_Con

[b+c]

1.64

2.31

1.73

7.85

Loc_Con

[a+c]

3.61

5.26

1.17

-

Loc_Land_Con

[a+b+c]

-

-

0.26

-

Residuals

 

84.46

77.08

91.99

80.76

 

Total var. expl. roof

15.54

22.92

8.01

19.24

Ground community

Loc

[a]

3.97 **

4.50 **

1.00

0.50

Land

[b]

2.80 *

4.33 **

0.61

4.98 **

Con

[c]

-

1.54

4.10 **

1.39

Loc_Land

[a+b]

2.48

3.84

0.36

1.57

Land_Con

[b+c]

-

7.93

2.78

4.90

Loc_Con

[a+c]

-

3.05

1.94

3.92

Loc_Land_Con

[a+b+c]

-

0.98

1.24

0.99

Residuals

 

90.75

73.84

87.96

81.75

 

Total var. expl. ground

9.25

26.16

12.04

18.25

Roof+Ground community

Loc

[a]

4.45 **

10.08 **

4.61 **

5.79 **

Land

[b]

1.09 *

1.18 *

0.37

3.75 **

Con

[c]

4.83 **

3.38 **

1.99 **

4.69 **

Loc_Land

[a+b]

1.71

1.11

0.32

-

Land_Con

[b+c]

0.27

2.24

1.58

3.04

Loc_Con

[a+c]

2.53

1.38

1.24

-

Loc_Land_Con

[a+b+c]

0.02

2.70

0.83

1.93

Residuals

 

85.09

77.94

89.05

81.17

 

Total var. expl. roof+ground

14.91

22.06

10.95

18.83


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