Ecological Archives E088-123-A1

Jeremy M. Wojdak and Gary G. Mittelbach. 2007. Consequences of niche overlap for ecosystem functioning: an experimental test with pond grazers. Ecology 88:2072–2083.

Appendix A. ANOVA results for snail species richness and composition effects.

ANOVA results for snail species richness and composition effects on (A) snail, periphyton, and macrophyte biomass and (B) sedimentation rate, dissolved oxygen concentration, and total system organic matter. Periphyton, organic matter, and sedimentation data were log transformed prior to analyses. Dissolved oxygen and periphyton data were means of several repeated measures. Response variables with error degrees of freedom not equal to 75 had missing data for one or two microcosms.


A) Functional group biomass

 

Snail biomass

Periphyton biomass

Plant biomass

 


Source

df

MS

F

P

df

MS

F

P

df

MS

F

P





Species richness

1

14842

29.328

<0.0001

1

0.807

4.162

0.0449

1

0.482

1.527

0.2204

Composition (SR)

19

4118.8

8.138

<0.0001

19

3.748

19.340

<0.0001

19

0.402

1.273

0.2270

Error

75

506.1

   

74

0.194

   

75

0.316

   
                         

B) System level properties

 

Dissolved oxygen

Sedimentation rate

Total organic matter

 


Source

df

MS

F

P

df

MS

F

P

df

MS

F

P





Species richness

1

0.292

2.663

0.1069

1

0.486

1.452

0.2320

1

1.030

4.124

0.0459

Composition (SR)

19

0.532

4.853

<0.0001

19

0.692

2.065

0.0142

19

0.714

2.859

0.0007

Error

75

0.110

   

75

0.335

   

73

0.250

   



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