Ecological Archives E096-114-A2

Adam F. A. Pellegrini, Lars O. Hedin, A. Carla Staver, and Navashni Govender. 2015. Fire alters ecosystem carbon and nutrients but not plant nutrient stoichiometry or composition in tropical savanna. Ecology 96:12751285. http://dx.doi.org/10.1890/14-1158.1

Appendix B. Tables illustrating statistical test results and descriptive statistics of tissue stoichiometry and community composition, and figures displaying tissue C:P ratios and community composition of trees.

Table B1. Statistical results from the linear mixed-effects model (all tests had 15 soil samples per plot nested within each experimental plot; denDF = 16 in all tests), with Tukey's HSD used to compare across treatments. Treatments are: 0 = unburned, 1 = 1yr FRT, and 3 = 3yr FRT.

Total soil pool

variable

 

comparison

 

p value

         

Total C

 

Treatment

 

0.005

   

0–1

 

<0.001

   

0–3

 

0.004

   

31

 

0.580

Total N

 

Treatment

 

<0.001

   

0–1

 

<0.001

   

0–3

 

<0.001

   

31

 

0.610

Total P

 

Treatment

 

0.865

 

Table B2. Statistical results from ANOVAs of fire treatment effect on the size of tree biomass pools, with Tukey's HSD used to compare across treatments. Treatments are: 0 = unburned, 1 = 1yr FRT, and 3 = 3yr FRT.

Woody plant pool

variable

 

comparison

 

p value

         

Total C

 

Treatment

 

0.007

   

0–1

 

<0.001

   

0–3

 

<0.001

   

3–1

 

0.02

Total N

 

Treatment

 

0.007

   

0–1

 

<0.001

   

0–3

 

0.002

   

3–1

 

0.007

Total P

 

Treatment

 

0.015

   

0–1

 

<0.001

   

0–3

 

0.003

 

 

31

 

0.09

 

Table B3. Statistical results from ANOVAs of fire treatment effect on the size of grass biomass pools, with Tukey's HSD used to compare across treatments. Treatments are: 0 = unburned, 1 = 1yr FRT, and 3 = 3yr FRT.

Grass pool

variable

 

comp

 

p value

         

Total C

 

Treatment

 

0.16

   

01

 

0.11

   

03

 

0.98

   

3–1

 

0.08

Total N

 

Treatment

 

0.26

Total P

 

Treatment

 

0.67

 

 

 

 

 

 

Table B4. Statistical results from ANOVA analyses of the effect of fire treatment on tissue stoichiometries across three different taxonomic selections: (1) All taxonomic groups; (2) Woody plants only; and (3) Grasses only. *Omocarpum outlier excluded (when included p < 0.069); §Flueggia virosa excluded (when included p < 0.026 for foliage and p < 0.08 for roots).

 

1) ALL TAXONOMIC GROUPS IN ANALYSIS:

Variable

Foliage

Roots

C:N

N.S.

N.S.

C:P

N.S.

N.S.

N:P

N.S.

N.S.*

 

2) WOODY PLANTS ONLY:


Variable

Foliage

Roots

C:N

N.S.

N.S.

C:P

N.S.

N.S.

N:P

N.S.§

N.S.§

 

3) GRASSES ONLY:

Variable Foliage Roots
C:N

N.S.

N.S.

C:P

N.S.

p < 0.049

N:P

N.S.

p < 0.076


 

Table B5. Mean (µ) and standard deviation (σ) of tissue stoichiometric ratios across plant species in both foliar (Fol) and root (Root) tissues (n = 3 experimental plots; in each experimental plot leaves were collected and averaged from 6 individuals and roots from 3 individuals). All samples are from the 1yr FRT plots. Species definitions: A. nig = Acacia nigrescens, D. cin = Dichrostachys cinerea, C. sch = Commiphora schimperii., F. vir = Flueggea virosa, C. imb = Combretum imberbe, O. tri = Ormocarpum trichocarpum, and S. bir = Sclerocarya birrea.

 

 

 

C:N

 

C:P

 

N:P

     

µ

σ

 

µ

σ

 

µ

σ

A. nig

Fol

 

14

1

 

229

40

 

16.2

2.1

Root

 

51

2

 

966

132

 

19.0

3.2

D. cin

Fol

 

23

1

 

310

7

 

13.5

0.4

Root

 

57

1

 

551

45

 

9.7

1.0

E. rig

Fol

 

19

1

 

214

23

 

11.2

1.3

Root

 

92

10

 

356

182

 

3.9

1.5

C. imb

Fol

 

16

3

 

288

39

 

18.2

0.7

Root

 

35

2

 

561

7

 

16.0

0.1

O. tri

Fol

 

19

2

 

281

50

 

14.8

4.4

Root

 

33

9

 

316

193

 

9.5

2.8

C. sch

Fol

 

14

1

 

224

25

 

15.5

2.6

Root

 

39

10

 

314

83

 

8.1

1.7

S. bir

Fol

 

14

2

 

272

86

 

18.8

3.2

Root

 

28

11

 

718

221

 

25.3

14.9

F. vir

Fol

 

26

5

 

295

27

 

11.5

0.4

Root

 

57

19

 

423

83

 

7.4

1.7

Grass

Fol

 

45

13

 

114

28

 

2.5

1.2

Root

 

55

6

 

254

81

 

4.6

1.8

 

Table B6. Mean (µ) and standard deviation (σ) of tissue stoichiometric ratios across plant species in both foliar (Fol) and root (Root) tissues (n = 3 experimental plots; in each experimental plot leaves were collected and averaged from 6 individuals and roots from 3 individuals). All samples are from the unburned plots. Species definitions: A. nig = Acacia nigrescens, D. cin = Dichrostachys cinerea, C. sch = Commiphora schimperii., F. vir = Flueggea virosa, C. imb = Combretum imberbe,O. tri = Ormocarpum trichocarpum, and S. bir = Sclerocarya birrea.

 

 

 

C:N

 

C:P

 

N:P

     

µ

σ

 

µ

σ

 

µ

σ

A. nig

Fol

 

16

1

 

272

44

 

16.7

2.3

Root

 

43

12

 

476

184

 

11.1

9.2

D. cin

Fol

 

23

3

 

295

78

 

12.8

1.3

Root

 

71

14

 

414

40

 

5.9

4.8

E. rig

Fol

 

19

2

 

135

89

 

7.1

4.1

Root

 

45

15

 

249

228

 

5.5

3.1

C. imb

Fol

 

17

2

 

304

37

 

17.6

1.3

Root

 

34

14

 

546

41

 

16.2

4.8

O. tri

Fol

 

21

1

 

212

45

 

10.1

1.7

Root

 

50

16

 

369

136

 

7.4

3.2

C. sch

Fol

 

16

2

 

135

40

 

8.7

2.8

Root

 

56

11

 

249

76

 

4.4

1.5

S. bir

Fol

 

15

0

 

296

32

 

19.4

2.1

Root

 

37

6

 

481

130

 

12.9

4.7

F. vir

Fol

 

23

5

 

223

49

 

9.7

1.9

Root

 

72

22

 

395

298

 

5.5

5.5

Grass

Fol

 

48

19

 

184

116

 

5.6

5.0

Root

 

63

15

 

488

110

 

7.8

0.4

 

Table B7. Statistical results from the community composition (species replicated within each of 3 functional types; see text) data across the four metrics: (1) changes in relative (fraction within each plot) biomass 1954–2012; (2) changes in relative abundance 1954–2012; (3) relative biomass in 2012; (4) relative abundance in 2012. The interaction term (A, fire by functional type) indicates whether functional types differed in their response (either abundance or biomass) to fire. The direct effect of fire on N2 fixers (column B) evaluates the hypothesis that fire promotes the relative abundance or biomass of N2-fixing plants.

 

A. Interactive effect of
fire × functional type:

B. Direct effect of fire on N2 fixers:

1) Δ% biomass

F4,59 = 0.34, p = 0.82

F1,16 = 0.38, p = 0.55

2) Δ% abundance

F4,59 = 0.68, p = 0.61

F1,16 = 0.52, p = 0.48

3) % biomass

F4,59 = 0.52, p = 0.72

F1,16 = 0.1, p = 0.76

4) % abundance

F4,59 = 0.61, p = 0.66

F1,16 = 0.46, p = 0.51

 

Table B8. Descriptive statistics of changes in the relative biomass and abundance (fraction within each plot) of the seven focal species (mean and standard error) in the unburned and 1yr FRT experimental plots. Species definitions: A. nig = Acacia nigrescens, D. cin = Dichrostachys cinerea, C. sch = Commiphora schimperii., F. vir = Flueggea virosa, C. imb = Combretum imberbe,O. tri = Ormocarpum trichocarpum, and S. bir = Sclerocarya birrea. All results are percentages.

 

Species

 

Δ% biomass (2012–1956)

SE

Δ% abundance (2012–1956)

SE

   

Unburned

A. nig

 

27.8

13.3

-22.1

7.1

D. cin

 

-6.6

3.8

6.3

3.1

O. tri

 

3.8

1.6

-6.3

2.6

E. rig

 

4.4

3.5

13.0

4.6

F. vir

 

-27.7

1.4

8.3

13.4

C. sch

 

-6.1

5.4

9.3

6.1

C. imb

 

-1.9

4.7

0.9

4.8

S. bir

 

0.1

0.2

1.6

0.4

   

1yr FRT

A. nig

 

22.2

8.8

-17.0

5.2

D. cin

 

-1.5

4.2

7.4

11.8

O. tri

 

3.8

2.4

-6.3

6.5

E. rig

 

3.1

1.1

2.0

3.8

F. vir

 

-15.1

7.7

4.6

7.6

C. sch

 

-0.6

-0.7

1.9

 

C. imb

 

2.7

1.7

-1.1

0.8

S. bir

 

0.1

1.9

2.9

0.7

 

FigB1

Fig. B1. Tissue C:P ratios of vegetation foliar (F) and root (R) tissue (mean +/- standard deviation) in the unburned (blue) and 1yr FRT (red) fire treatments across 4 functional taxonomic groups. Species definitions: A. nig = Acacia nigrescens, D. cin = Dichrostachys cinerea, C. sch = Commiphora schimperii., F. vir = Flueggea virosa, C. imb = Combretum imberbe,O. tri = Ormocarpum trichocarpum, and S. bir = Sclerocarya birrea.


 

 

FigB2

Fig. B2. Community composition of trees and shrubs across the unburned (blue) and 1yr FRT (red) fire treatments. (A) Relative biomass of each plant species in proportion to the entire plot-level biomass (mean +/- standard deviation). (B) Relative abundance of each plant species expressed as a fraction of the total number of plants in a plot (mean +/- standard deviation). Species definitions: A. nig = Acacia nigrescens, D. cin = Dichrostachys cinerea, C. sch = Commiphora schimperii., F. vir = Flueggea virosa, C. imb = Combretum imberbe,O. tri = Ormocarpum trichocarpum, and S. bir = Sclerocarya birrea.


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