Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian <i>terra firme</i> rainforest

SANTOS, Emily Darc Andrade dos; TNG, David Yue Phin; APGAUA, Deborah Mattos Guimarães; ASSUNÇÃO, Raul Reis; MANZI, Antônio Ocimar

doi:10.1590/1809-4392202103471

Emily Darc Andrade dos SANTOS ^** Corresponding author: emilyandrad@gmail.com

Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo 2936, Aleixo,69060-001, Manaus-AM, Brazil

https://orcid.org/0000-0001-5127-7390

David Yue Phin TNG

Centre for Rainforest Studies, The School for Field Studies, PO Box 141, Yungaburra, QLD 4884, Australia

James Cook University, College of Science and Engineering, Centre for Tropical, Environmental and Sustainability Sciences, 14-88 McGregor Rd, Smithfield Qld 4878, Australia

Deborah Mattos Guimarães APGAUA

Centre for Rainforest Studies, The School for Field Studies, PO Box 141, Yungaburra, QLD 4884, Australia

James Cook University, College of Science and Engineering, Centre for Tropical, Environmental and Sustainability Sciences, 14-88 McGregor Rd, Smithfield Qld 4878, Australia

Raul Reis ASSUNÇÃO

Universidade Federal de Lavras, Aquenta Sol, 37200-900, Lavras-MG, Brazil

Antônio Ocimar MANZI

Instituto Nacional de Pesquisas Espaciais, Rod. Presidente Dutra, km 40 SP/RJ, 12630-970 Cachoeira Paulista-SP, Brazil

* Corresponding author: emilyandrad@gmail.com

ASSOCIATE EDITOR:

Lucia Fuchslueger

Figures (2)
Tables (5)

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Figure 1
Monthly means of soil phosphorus (P) fractions in surface soil of three sampling plots representing three soil types in a central Amazon terra firme rainforest in Brazil. Soil types are acrisol (triangles), ferrasol (squares) and podsol (circles). Inorganic P fractions: P-resin (A); P_i-NaHCO₃ (B); P_i-NaOH (C); and; P-HCl (D). Organic P fractions: P_o-NaHCO₃ (E); P_o-NaOH (F). Overall soil fractions: P-Total (G); P-Labile (H); P-Residual (I). Error bars denote the standard error.

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Figure 2
Monthly means of attributes of leaf litter sampled in a terra firme central Amazonian rainforest in Brazil in three soil types: acrisol (triangles), ferralsol (squares), and podsol (circles). A - monthly leaf litter production (lines) and rainfall (grey bars); B - P in the leaf litterfall; C - P input into the soil. Error bars denote the standard error. Different lowercase letters indicate significant differences between soil types according to Tukey’s post-hoc tests using data from April to August. See for significant differences between months for each soil fraction within each soil type.

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Table 1
Characteristics of sampling plots for three soil types and leaf litter in a terra firme rainforest in the central Amazon in Brazil, and particle size distribution in a composite sample of five subsamples of 0-5-cm top soil from each plot.

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Table 2
Phosphorus (P) fraction concentrations (mg kg^-1) within samples of three soil types in a terra firme rainforest in the central Amazon in Brazil. % P-Total = mean percentage of each fraction relative to the P-Total concentration. The values are the mean ± standard deviation of five composite samples (one sample per month from April to August, except P-Total and P-Residual of podsol, which are based on four samples from April to July) (see Material and Methods for details). Lowercase letters denote significant differences between soil types according to Tukey’s post-hoc tests using data from April to August (to July for P-Total and P-Residual). See for significant differences between months for each soil fraction within each soil type.

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Table 3
F-statistics and p-values (in parentheses) of repeated-measures ANOVA for the effect of soil type and sampling month on soil phosphorus (P) fractions in three soil types (acrisol, ferralsol and podsol) and leaf litter parameters in samples from a terra firme rainforest in the central Amazon in Brazil. Analyses are based on five samples per soil type from each of five months (April to August), except P-Total and P-Residual, which are based on four months (April to July) (see Materials and Methods for details). Degrees of freedom = 2, 12 in all cases. Significant statistics are in bold.

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Table 4
Monthly phosphorus fraction concentrations (mg kg^-1) and leaf litterfall attributes for three soil types in a terra firme rainforest in the central Brazilian Amazon. Only attributes that varied significantly among months are shown (see ). Values are the mean ± standard deviation of five sub-samples along a 125-m transect (see Material and Methods for details). The lowercase letters indicate significant differences between months within each attribute according to a Tuckey test. See and 2, respectively, for monthly variation in all soil P and leaf litter attributes.

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Table 5
Parameter estimates and random effect standard deviation (SD) for linear mixed effects models fitting phosphorus (P) fraction responses to leaf litter P input and soil type (acrisol, ferralsol, podsol) as fixed effects and collection month as a random effect. Analyses are based on five subsamples per soil type from each of five months (April to August), except P-Total and P-Residual for podsol, which are based on four months (April to July). Significant effects are marked in bold.

Soil type	Topographic position	Altitude (m)	Drainage	Particle size distribution (%)
Soil type	Topographic position	Altitude (m)	Drainage	Sand	Silt	Clay
Acrisol	Hill slope	82	Good	32.1	7.4	54.5
Ferralsol	Plateau	99	Good	10.8	9.5	79.7
Podsol	Valley	62	Poor	94.3	0.1	5.5

P-fraction	Acrisol	% P-Total	Ferralsol	% P-Total	Podsol	% P-Total
Inorganic
P-resin	9.59 ± 0.82 a	8.9%	11.92 ± 1.08 b	7.7%	3.74 ± 0.42 c	11.1%
P_i-NaHCO₃	3.53 ± 1.80 a	3.4%	3.62 ± 1.53 a	2.5%	3.26 ± 1.47 a	9. 9%
P_i-NaOH	13.82 ± 4.65 a	14.6%	17.41 ± 5.16 b	12.1%	4.50 ± 2.29 c	13.6%
P-HCl	1.96 ± 0.7 a	1.7%	2.37 ± 0.86 b	1.4%	1.49 ± 1.12 c	3.1%
Organic
P_o-NaHCO₃	2.44 ± 1.24 a	2.2%	4.75 ± 3.65 b	3.5%	2.4 ± 0.80 b	6.8%
P_o-NaOH	14.22 ±7.33 a	12.0%	21.70 ± 10.56 b	13.3%	8.26 ± 4.43 c	20.8%
Overall
^#P-Total	105.25 ± 8.68 a	NA	152.04 ± 2.79 b	NA	27.79 ± 3.92 c	NA
^#P-Residual	59.69 ± 13.73 a	57.4%	90.26 ± 7.83 b	59.6%	10.20 ± 5.02 c	34.6%
P-Labile	15.55 ± 3.15 a	14.5%	20.29 ± 5.40 b	13.7%	9.40 ± 2.40 c	27.8%

P-fraction	Soil type	Month	Soil type x month
Inorganic
P-resin	100.87 (< 0.001)	3.92 (0.071)	0.03 (0.974)
P_i-NaHCO₃	0.448 (0.649)	8.42 (0.013)	2.62 (0.110)
P_i-NaOH	93.66 (< 0.001)	26.99 (< 0.001)	0.30 (0.746)
P-HCl	37.42 (< 0.001)	329.86 (< 0.001)	21.36 (< 0.001)
Organic
P_o-NaHCO₃	182.87 (< 0.001)	1.79 (0.206)	1.04 (0.385)
P_o-NaOH	30.04 (< 0.001)	30.72 (<0.001)	1.16 (0.346)
Overall
P-Total	172.51 (< 0.001)	2.38 (0.149)	0.57 (0.582)
P-Residual	169.00 (< 0.001)	3.76 (0.076)	1.33 (0.290)
P-Labile	62.17 (< 0.001)	0.179 (0.680)	0.37 (0.697)
Leaf litter
Dry mass	4.89 (0.028)	50.35 (< 0.001)	8.30 (0.005)
Leaf P	1.22 (0.329)	0.45 (0.517)	0.94 (0.418)
Leaf P input	4.573 (0.172)	14.54 (0.002)	1.13 (0.356)

Attribute	Collection month
Attribute	April	May	June	July	August
Acrisol
P_i-NaHCO₃	6.11 ± 1.55 a	2.97 ± 1.41 bc	2.35 ± 0.90 bc	2.53 ± 0.80 b	3.69 ± 1.37 ac
P_i-NaOH	15.15 ± 6.16 ab	16.98 ± 4.06 b	15.71 ± 3.98 ab	11.36 ± 3.17 ab	9.92 ± 1.95 b
P-HCl	1.41 ± 0.62 a	1.52 ± 0.55 a	1.77 ± 0.50 a	1.93 ± 0.27 ab	3.16 ± 0.43b
P_o-NaOH	2.85 ± 2.26 ab	5.94 ± 2.49 a	2.77 ± 2.39 a	7.53 ± 2.67 ab	3.04 ± 1.60 b
Leaf dry mass	4.88 ± 1.16 ab	9.19 ± 4.18 b	11.40 ± 8.05 b	10.76 ± 2.07 c	12.11 ± 5.22 d
Leaf P input	0.82 ± 0.21 a	2.13 ± 1.09 b	3.28 ± 1.80 c	2.95 ± 0.84 c	5.14 ± 1.27 c
Ferralsol
P_i-NaHCO₃	5.32 ± 1.12 a	2.76 ± 1.12 bc	3.43 ± 1.49 a	3.87 ± 1.47 c	3.82 ± 1.08 a
P_i-NaOH	19.68 ± 4.75 a	25.34 ± 11.27 ab	19.87 ± 3.7 ab	12.86 ± 3.18 b	14.99 ± 3.97 ab
P-HCl	1.51 ± 0.25 a	1.49 ± 0.36 ab	2.14 ± 0.83 b	3.00 ± 0.35 c	3.38 ± 0.27 c
Leaf dry mass	7.3 ± 2.07 ab	9.32 ± 4.34 abc	12.97 ± 4.46 bc	25.75 ± 12.40 cd	26.45 ± 13.68 d
Leaf P input	1.50 ± 0.68 a	1.80 ± 0.63 ab	3.17 ± 1.11 ab	8.99 ± 5.90 b	6.07 ± 4.48 ab
Podsol
P_i-NaHCO₃	5.07 ± 0.62 a	2.54 ± 1.64 bc	2.24 ± 0.99 bc	3.29 ± 1.64 ac	3.14 ± 0.47 ac
P_i-NaOH	4.89 ± 2.88 ab	5.43 ± 2.81 ab	6.13 ± 1.36 a	2.32 ± 1.26 b	3.74 ± 0.69 ab
P-HCl	0.70 ± 0.19 ab	0.54 ± 0.19 a	1.05 ± 0.32 b	1.89 ± 0.17 c	3.27 ± 0.65 d
P_o-NaOH	4.72 ± 1.92 ab	5.49 ± 3.20 b	5.86 ± 3.14 b	11.65 ± 2.63 b	13.60 ± 2.25 c

P fraction	Intercept	Leaf litterfall P input	Ferralsol	Podsol	Random effect (month) SD
Inorganic
P-resin	21.838 (< 0.001)	0.017 (0.060)	0.193 (0.016)	-10.002 (< 0.001)	0.274
P_i-NaHCO₃	10.878 (< 0.001)	0.019 (0.207)	0.032 (0.772)	-0.100 (0.375)	0.379
P_i-NaOH	26.138 (< 0.001)	-0.014 (0.339)	0.259 (0.015)	-11.968 (< 0.001)	0.363
P-HCl	0.585 (0.010)	-0.003 (0.796)	0.185 (0.053)	-4.802 (<0.001)	0.327
Organic
P_o-NaHCO₃	0.602 (< 0.001)	0.051 (0.025)	0.411 (0.023)	-0.011 (0.950)	0.615
P_o-NaOH	23.984 (< 0.001)	-0.009 (0.670)	0.534 (< 0.001)	-0.505 (0.001)	0.523
Overall
P-Total	4.641 (< 0.001)	-0.002 (0.811)	0.387 (< 0.001)	-1.110 (< 0.001)	0.178
P-Labile	3.728 (< 0.001)	0.008 (0.220)	0.353 (< 0.001)	-0.623 (< 0.001)	0.177
P-Residual	4.132 (< 0.001)	-0.024 (0.225)	0.447 (0.003)	-1.692 (< 0.001)	0.441

[1] * Corresponding author: emilyandrad@gmail.com

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Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest

ABSTRACT