Ecological Archives E095-009-A2

Sally E. Koerner, Scott L. Collins. 2014. Interactive effects of grazing, drought, and fire on grassland plant communities in North America and South Africa. Ecology 95:98–109. http://dx.doi.org/10.1890/13-0526.1

Appendix B. Statistical results of split-plot ANOVA for grass and forb ecosystem measurements in response to simulated grazing and precipitation treatments.

Table B1. Split-plot analysis of variance results testing the effects of the precipitation treatment (Drought, D) and simulated grazing treatment (Clipping, Clip) on grass and forb stems per 0.1-m² and grass and forb ANPP per 1-m² for end of season 2011. Each metric in each site and each burn frequency was evaluated with a separate model. All measures and blocks have n = 7 except for the Konza infrequently burned block which has an n = 6 due to a wildfire. Satterthwaite degrees of freedom were calculated to correct for unequal variances. Significant values are in bold (P < 0.05).

Burn Block

Site

Parameter

 

Grass Stems

 

Grass ANPP

 

Forb Stems

 

Forb ANPP

 

df

F value

P value

 

df

F value

P value

 

df

F value

P value

 

df

F value

P value

Infrequent

Konza

Drought

1, 12

4.91

0.047

 

1, 10

12.13

0.006

 

1, 12

1.01

0.33

 

1, 10

0.53

0.48

Clipping

1, 12

21.07

<0.001

 

1, 10

11.91

0.006

 

1, 12

1.14

0.31

 

1, 10

0.10

0.76

D*Clip

 

1, 12

6.11

0.029

 

1, 10

1.39

0.27

 

1, 12

0.08

0.78

 

1, 10

2.75

0.13

Kruger

Drought

1, 12

3.38

0.091

 

1, 18

4.39

0.051

 

1, 18

2.39

0.14

 

1, 24

0.02

0.88

Clipping

1, 12

0.61

0.45

 

1, 18

11.44

0.003

 

1, 18

2.39

0.14

 

1, 24

0.16

0.69

D*Clip

 

1, 12

1.25

0.29

 

1, 18

5.56

0.030

 

1, 18

4.69

0.044

 

1, 24

0.06

0.82

Frequent

Konza

Drought

1, 6

8.08

0.029

 

1, 6

0.73

0.43

 

1, 12

0.75

0.40

 

1, 12

2.28

0.16

Clipping

1,12

4.07

0.067

 

1, 12

45.23

<0.001

 

1, 12

2.54

0.14

 

1, 12

0.57

0.47

D*Clip

 

1, 12

2.35

0.15

 

1, 12

0.79

0.39

 

1, 12

6.70

0.024

 

1, 12

0.01

0.94

Kruger

Drought

1, 6

7.80

0.032

 

1, 12

1.03

0.33

 

1, 24

0.00

1.00

 

1, 18

0.08

0.78

Clipping

1, 12

0.70

0.42

 

1, 12

12.27

0.004

 

1, 24

1.14

0.30

 

1, 18

2.27

0.15

D*Clip

 

1, 12

1.71

0.22

 

1, 12

0.65

0.43

 

1, 24

0.29

0.60

 

1, 18

1.15

0.30


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