Ecological Archives E087-167-A1

Selene Báez, Scott L. Collins, David Lightfoot, and Terri L. Koontz. 2006. Bottom-up regulation of plant community structure in an aridland ecosystem. Ecology 87:2746–2754.

Appendix A. Repeated-measures analysis of cover and species richness of functional types in grass- and shrub-dominated vegetation in areas with and without rodents. V = vegetation type, Tr = rodent access/removal treatment, and V × Tr their interaction.

 

Cover

Species richness

 

SS

df

F

P

SS

df

F

P

Summer annuals

               

V

7.953

1,12

95.438

<0.001

5.035

1,12

60.417

<0.001

Tr

0.065

1,12

0.784

0.393

0.04

1,12

0.478

0.503

V × Tr

0.351

1,12

4.211

0.063

0.008

1,12

0.095

0.763

Overall

8.369

3,12

33.477

<0.001

5.083

3,12

20.33

<0.001

Winter annuals

               

V

0

1,12

0

0.994

1.974

1,12

23.693

<0.001

Tr

0.291

1,12

3.494

0.086

0.045

1,12

0.54

0.477

V × Tr

0.054

1,12

0.643

0.438

0.151

1,12

1.818

0.203

Overall

0.345

3,12

1.379

0.297

2.171

3,12

8.684

0.003

Forbs

               

V

3.944

1,12

47.323

<0.001

4.625

1,12

55.498

<0.001

Tr

0.037

1,12

0.45

0.516

0.005

1,12

0.06

0.811

V × Tr

0.07

1,12

0.84

0.377

0.025

1,12

0.302

0.593

Overall

4.051

3,12

16.204

<0.001

4.655

3,12

18.62

<0.001

Grasses

               

V

18.062

1,12

216.743

<0.001

6.311

1,12

75.733

<0.001

Tr

0.014

1,12

0.171

0.687

0.003

1,12

0.037

0.851

V × Tr

0.032

1,12

0.38

0.549

0.018

1,12

0.211

0.648

Overall

18.108

3,12

72.431

<0.001

6.332

3,12

25.33

<0.001

Shrubs

               

V

8.639

1,12

103.666

<0.001

0.586

1,12

7.033

0.021

Tr

0

1,12

0.004

0.949

0.024

1,12

0.293

0.598

V × Tr

0.022

1,12

0.269

0.613

0.003

1,12

0.031

0.863

Overall

8.662

3,12

34.647

<0.001

0.613

3,12

2.452

0.114

Total

               

V

1.397

1,12

16.77

0.002

4.703

1,12

56.441

<0.001

Tr

0.002

1,12

0.019

0.893

0.01

1,12

0.123

0.732

V × Tr

0

1,12

0.001

0.983

0.003

1,12

0.032

0.861

Overall

1.398

3,12

5.593

0.012

4.716

3,12

18.865

<0.001

Heterogeneity

               

V

0.636

1,12

7.63

0.017

       

Tr

0.293

1,12

3.515

0.085

       

V × Tr

0.032

1,12

0.381

0.549

       

Overall

0.96

3,12

3.842

0.039

       


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