Ecological Archives E096-114-A2

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 96:1275–1285. 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
	3–1	0.580
Total N	Treatment	<0.001
	0–1	<0.001
	0–3	<0.001
	3–1	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
	3–1	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
	0–1	0.11
	0–3	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
A. nig	Root	51	2	966	132	19.0	3.2
D. cin	Fol	23	1	310	7	13.5	0.4
D. cin	Root	57	1	551	45	9.7	1.0
E. rig	Fol	19	1	214	23	11.2	1.3
E. rig	Root	92	10	356	182	3.9	1.5
C. imb	Fol	16	3	288	39	18.2	0.7
C. imb	Root	35	2	561	7	16.0	0.1
O. tri	Fol	19	2	281	50	14.8	4.4
O. tri	Root	33	9	316	193	9.5	2.8
C. sch	Fol	14	1	224	25	15.5	2.6
C. sch	Root	39	10	314	83	8.1	1.7
S. bir	Fol	14	2	272	86	18.8	3.2
S. bir	Root	28	11	718	221	25.3	14.9
F. vir	Fol	26	5	295	27	11.5	0.4
F. vir	Root	57	19	423	83	7.4	1.7
Grass	Fol	45	13	114	28	2.5	1.2
Grass	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
A. nig	Root	43	12	476	184	11.1	9.2
D. cin	Fol	23	3	295	78	12.8	1.3
D. cin	Root	71	14	414	40	5.9	4.8
E. rig	Fol	19	2	135	89	7.1	4.1
E. rig	Root	45	15	249	228	5.5	3.1
C. imb	Fol	17	2	304	37	17.6	1.3
C. imb	Root	34	14	546	41	16.2	4.8
O. tri	Fol	21	1	212	45	10.1	1.7
O. tri	Root	50	16	369	136	7.4	3.2
C. sch	Fol	16	2	135	40	8.7	2.8
C. sch	Root	56	11	249	76	4.4	1.5
S. bir	Fol	15	0	296	32	19.4	2.1
S. bir	Root	37	6	481	130	12.9	4.7
F. vir	Fol	23	5	223	49	9.7	1.9
F. vir	Root	72	22	395	298	5.5	5.5
Grass	Fol	48	19	184	116	5.6	5.0
Grass	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	F_4,59 = 0.34, p = 0.82	F_1,16 = 0.38, p = 0.55
2) Δ% abundance	F_4,59 = 0.68, p = 0.61	F_1,16 = 0.52, p = 0.48
3) % biomass	F_4,59 = 0.52, p = 0.72	F_1,16 = 0.1, p = 0.76
4) % abundance	F_4,59 = 0.61, p = 0.66	F_1,16 = 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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