Ecological Archives M076-001-A3

John L. Maron, James A. Estes, Donald A. Croll, Eric M. Danner, Sarah C. Elmendorf, and Stacey L. Buckelew. 2006. An introduced predator alters Aleutian Island plant communities by thwarting nutrient subsidies. Ecological Monographs 76:3–24.

Appendix C. Nested ANCOVA results testing effects of island type (fox-free or fox-infested), island size (log transformed) and island identity nested within island type on extractable soil phosphorus, δ15N soil, grass and Achillea borealis and graminoid biomass.

Response variable: Extractable soil P

Source

df

MS

F

P

Island type

1

2.7

18.1

0.0009

Island size

1

1.9

17.7

0.0008

Island identity(type)

15

0.12

  7.9

0.0001

Error

 

275

4.2

 

Response variable: δ15N soil

Source

df

MS

F

P

Island type

1

1891

20.6

0.0004

Island size

1

220

3.4

0.08

Island identity(type)

15

75.9

13.7

0.0001

Error

 

272

5.5

 

Response variable: δ15N grass

Source

df

MS

F

P

Island type

1

2707

38.9

0.0001

Island size

1

449

6.9

0.02

Island identity(type)

15

56.0

3.1

0.0003

Error

 

123

18.3

 

Response variable: δ15N Achillea borealis

Source

df

MS

F

P

Island type

1

293.4

6.3

0.03

Island size

1

0.09

0.0

0.97

Island identity(type)

15

41.7

4.7

0.0001

Error

 

88

8.8

 

Response variable: graminoid biomass

Source

df

MS

F

P

Island type

1

170.5

64.7

0.0001

Island size

1

61.9

23.8

0.0003

Island identity(type)

15

2.6

1.1

0.36

Error

 

241

2.4

 


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