Ecological Archives E095-128-A1

Matthew E. S. Bracken, Renee E. Dolecal, Jeremy D. Long. 2014. Community context mediates the top-down vs. bottom-up effects of grazers on rocky shores. Ecology 95:1458–1463. http://dx.doi.org/10.1890/13-2094.1

Appendix A. Tables showing output from general linear models.

Table A1. Ammonium concentrations.

(a) Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

9

82.86

9.21

7.12

< 0.001

Error

288

372.29

1.29

 

 

Corrected Total

297

455.16

 

 

 

(b) Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Species

2

8.13

4.06

3.14

0.045

Grazer

2

63.29

31.65

24.48

< 0.001

Species × Grazer

4

7.41

1.85

1.43

0.223

Biomass

1

4.94

4.95

3.83

0.051

 

Table A2. Effects on Fucus growth.

(a) Consumptive effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

96.26

48.13

2.05

0.138

Error

57

1,336.24

23.44

 

 

Corrected Total

59

1,432.51

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Ulva

1

1.82

1.82

0.08

0.781

Biomass

1

59.92

59.92

2.56

0.115

(b) Facilitative effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

67.86

33.93

2.84

0.067

Error

57

681.80

11.96

 

 

Corrected Total

59

749.65

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Ulva

1

67.83

67.83

5.67

0.021

Biomass

1

15.73

15.73

1.32

0.256

(c) Total herbivore effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

189.76

94.88

4.15

0.021

Error

57

1,304.35

22.88

 

 

Corrected Total

59

1,494.11

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Ulva

1

91.89

91.89

4.02

0.049

Biomass

1

14.25

14.25

0.62

0.433

 

Table A3. Effects on Ulva growth.

(a) Consumptive effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

9,036.48

4,518.24

13.85

< 0.001

Error

57

18,590.53

326.15

 

 

Corrected Total

59

27,627.01

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Fucus

1

2,845.61

2,845.61

8.72

0.005

Biomass

1

8,989.47

8,989.47

27.56

< 0.001

(b) Facilitative effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

270.57

135.28

0.27

0.764

Error

57

28,545.08

500.79

 

 

Corrected Total

59

28,815.65

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Fucus

1

160.57

160.57

0.32

0.574

Biomass

1

7.55

7.55

0.02

0.903

(c) Total herbivore effects

Overall model

Source

df

Sum of squares

Mean Square

F value

P value

Model

2

9,605.60

4,802.80

7.80

0.001

Error

57

35,098.73

615.77

 

 

Corrected Total

59

44,704.33

 

 

 

Treatment effects

Treatment

df

Type III SS

Mean Square

F value

P value

Fucus

1

1,654.27

1,654.27

2.69

0.107

Biomass

1

9,517.97

9,517.97

15.46

< 0.001


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