The Effect of Carbonization on Wood Structure Of

IAWA Journal, Vol. 33 (1), 2012: 73–90

THE EFFECT OF CARBONIZATION ON WOOD STRUCTURE OF DALBERGIA VIOLACEA, STRYPHNODENDRON POLYPHYLLUM, TAPIRIRA GUIANENSIS, VOCHYSIA TUCANORUM, AND POUTERIA TORTA FROM THE BRAZILIAN CERRADO Thaís A.P. Gonçalves¹,², Carmen R. Marcati² and Rita Scheel-Ybert¹,*

Summary Brazil is the world’s largest producer of charcoal and a great part of this material still comes from native forests – especially from the cerrado biome, which is highly impacted by anthropogenic degradation. The need to control charcoal production increases the demand of charcoal identification, but there is little information about the anatomical modifications due to carbonization. In this paper, fresh and charred wood samples from five Brazilian species were analyzed (Dalbergia violacea, Stryph- nodendron polyphyllum, Tapirira guianensis, Vochysia tucanorum, and Pouteria torta). Anatomical characters were described and measurements of the main anatomical features of wood and charcoal were statistically compared. Minor modifications were observed: reduction of tangential vessel diameter was the most evident change after carbonization; shrinkage of rays (in width) occurred only in some individuals. The present study supports the identification of charred woods, hopefully contributing to the control of charcoal production, and to palaeoenvironmental and archaeobotanical studies. Key words: Wood anatomy, charcoal, anthracology, cerrado, Brazil.

Introduction The first identifications of charred wood were made by the end of the nineteenth century, and frequently related to archaeological samples (Heer 1865; Prejawa 1896; Breuil 1903). At that time, however, such studies were slow and hard to reproduce due to the difficulties of embedding and sectioning charcoal. Only after the 1960s, reflected light microscopy facilitated these analyses (e.g. Western 1963; Vernet 1973; Vernet & Thiébault 1987; Heinz & Thiébault 1998; Figueiral & Mosbrugger 2000; Théry- Parisot et al. 2010), giving rise to anthracology, a specialized field for the analysis and identification of charcoals based on wood anatomy (the word is derived from the Greek anthrakos, charcoal). In Brazil such studies started in the late 1990s, and were especially related to archaeobotany and palaeoenvironmental reconstruction (e.g. Scheel-Ybert 2000, 2001; Scheel-Ybert et al. 2003; Beauclair et al. 2009).

1) Museu Nacional, Universidade Federal do Rio de Janeiro (MN/UFRJ) – Departamento de Antro- pologia, Quinta da Boa Vista, São Cristóvão, 20940-040, Rio de Janeiro, Brazil. 2) Universidade Estadual Paulista (UNESP) – Departamento de Recursos Naturais, Ciências Florestais. CP 237, 18603-970, Botucatu, SP, Brazil. *) Corresponding author [E-mail: [email protected]].

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Recently, a new application for anthracological studies is developing in Brazil from the demand for charcoal identification (Gonçalves et al. 2008). The country is the world’s largest producer of charcoal, which is intensively used in industry (above 80% of all the charcoal produced), especially in iron and steel manufacturing (ABRAF 2009; FAO 2009). Charcoal is a very important biofuel; if produced from forest plantations its use has a positive carbon balance and it can support the income of numerous families (ABRAF 2009; BRASIL 2010). On the other hand, a great part of this material still comes from native forests, and the unskilled workers include children (Carneiro 2008; ABRAF 2009). Anthracology might contribute to help control illegal charcoal production, and thus contribute to nature conservation and also to charcoal technology. There is, however, still little information about the anatomical modifications due to charring of tropical species. Previous works analyzed the structural changes in charcoal prepared at different temperatures, either focusing on mass loss and volumetric shrinkage (e.g. McGinnes et al. 1971; Beall et al. 1974; Slocum et al. 1978), or analyzing the wood anatomy in more detail: (Prior & Alvin 1983, 1986; Prior & Gasson 1993; Kim & Hanna 2006; Kwon et al. 2009; Dias Leme et al. 2010). In spite of these important studies, the modifications in wood anatomy after charring are still poorly known, especially in Brazilian species. The present study aims to understand the anatomical changes in charcoals produced at 400 ºC. This temperature is the average temperature of the most common kilns used in Brazil, known as “hot-tail” (rabo quente) (Pennise et al. 2001; Pinheiro et al. 2005; Peláez-Samaniego et al. 2008). We also aim to understand the behaviour of different wood types during the the carbonization process, and to provide information on the wood anatomy of native Brazilian cerrado species. The cerrado biome, or Brazilian savanna, is highly impacted by anthropogenic degradation, including charcoal production. The ultimate aim of this study is to help identifying charred wood species, especially for the sake of controlling charcoal production, but also to trace charcoal from natural or illegal fires, and for palaeoenvironmental and archaeobotanical studies.

Materials and methods

Three different specimens from each of five species representative of the cerrado environment were analyzed: Dalbergia violacea (Jacq.) Hoffmanns. (Fabaceae, Faboideae); Stryphnodendron polyphyllum Mart. (Fabaceae, Mimosoideae); Tapirira guianensis Aubl. (Anacardiaceae); Vochysia tucanorum Mart. (Vochysiaceae); and Pouteria torta (Mart.) Radlk. (Sapotaceae). The species selection comprises a diversity of wood anatomical types (Metcalfe & Chalk 1950) that might be differently affected by the carbonization process. The samples were collected from a 180 ha private reserve of cerrado sensu lato in São Paulo state, Brazil (23º 02' 55.5" S and 48º 31' 26,1" W), where all the selected species are quite common (Marcati et al. 2006). Three-cm-thick discs were obtained from the basal portion of the most developed branches (diameter c. 3–5 cm) and divided into two parts, one for wood anatomy and one for anthracological analyses.

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For light microscopic wood anatomical study 15–20 µm thick sections (transverse, tangential, and radial) were cut with a sliding microtome, double-stained with safranin and astra blue (Roeser 1972), and permanently mounted in Entellan synthetic medium. For anthracological analyses, wood samples were wrapped in tinfoil and carbonized in a muffle furnace at 400ºC during 40 minutes. Charcoal samples were manually split according to the three wood planes and examined with reflected light brightfield/dark- field microscopy.SEM micrographs were obtained from gold-sputter-coated charcoal samples at the Instituto de Pesquisas Jardim Botanico do Rio de Janeiro. Wood samples and slides were deposited in the xylarium ‘Maria Aparecida Mourão Brasil’ (BOTw) (Departamento de Recursos Naturais, Universidade Estadual Paulista, UNESP). Charcoals were deposited in the Laboratória Arqueobotânica e Paisagem (Museu Nacional, Universidade Federal do Rio de Janeiro) charcoal collection. As there are no formal recommendations for charcoal studies, we used the IAWA Committee (1989) recommendations for descriptions and measurements of wood and charcoal anatomy. The only exception was intervessel pit diameter. As pit chambers are frequently indistinct in charcoal samples (Fig. 1), we measured the tangential diameter of the apertures, instead of the pit chambers. Tangential vessel diameter (µm) was cal- culated from 25 measurements; 10 measurements were taken for vessel frequency (vessels /mm²), tangential diameter of intervessel pit apertures (µm), ray frequency (rays/mm), ray width (µm), and ray height (µm). The results are presented as the means followed by the full range. The quantitative data were analyzed by SAS 9.1.3, statistical procedure PROC- GENMOD. Continuous variables (vessel diameter, intervessel pits aperture tangential diameter, ray width, ray height) were fitted using generalized linear models for repeated measurements assuming normal error (in case the variable passed the Kolmogorov- Smirnov test for normality), or gamma (in case it failed this test). Discrete variables

Figure 1. Dalbergia violacea intervessel pits, shown from the lumen side in charcoal (right). Scale bars: 10 μm (wood, on the left) and 2 μm (charcoal, on the right).

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– – – + + inclus. – – – canals elements traumatic Secretory m in. radial canals

– + + + + G – – – – + Fibres Septos 3 2 2 2 3 wt

1–3 1–2 Ser 1 (2) Rays 1–2 (3) –––––––––––––––––––––––––– (1–2) 3–5 (6)

long confluent A xial parenchyma scanty to vasicentric irregular marginal bands irregular marginal lozenge-aliform and diffuse vasicentric, lozenge-aliform, short and vasicentric, lozenge-aliform, confluent, long confluent forming lines and bands, in lines and bands, tendency to reticulate : similar to intervessel pits, >: larger than intervessel pits, 2t: of two distinct sizes and types); ≈

≈ ≈ ≈ VR >/2t ≈/>/2t

al al IP al/vs al/vs al/vs

Vessels s s s s s PP – – – + + Ty ––––––––––––––––––––––

+ + + + + GR Table 1. Anatomical characters of the species analysed. 1. Table Qualitative data: +: presence; –: absence; GR: growth rings; – Vessels Ty: tyloses, PP: pits perforation (al: alternate, plates vs: vestured), VR: (s: vessel-ray pits ( simple, m: multiple), IP: intervessel Character violacea Dalbergia

Species Rays – Ser: seriate, Fibres: wt: wall thickness (1: very thin, 2: thin between ()to indicate rare or sporadic characters. thick, 3: very thick), G: gelatinous. Min. inclus.: Mineral inclusions. Data Stryphnodendron

Tapirira guianensis Tapirira polyphyllum tucanorum Vochysia Pouteria torta

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(vessels and ray frequencies) were fitted using the same models, but assuming Poisson error. All data were also fitted using a log link function and a linear predictor with factorial structure. When necessary, LSMeans tests for multiple comparisons were performed. These analyzes were interpreted at a significance level of 5%. Therefore, significance levels lower than 5% indicate significant differences between wood and charcoal (increase or decrease in the measured values).

Results

Anatomical characters are described below for fresh and charred wood of the five Brazilian species. Measurements of the main anatomical features of wood and charcoal are statistically compared in Tables 2 & 3.

Dalbergia violacea (Fig. 1 & 2, Table 1) Growth rings: present, demarcated by thick-walled and radially flattened fibres; boundaries distinct in wood and charcoal. – Vessels: wood diffuse-porous; vessels solitary (32%) and in radial multiples of 2 (18%), 3 (19%) and 4 or more (31%); simple perforation plates; alternate intervessel pits, vestured; vessel-ray pits with distinct borders, similar to intervessel pits in size and shape throughout the ray cell. – Axial parenchyma: lozenge- and winged-aliform, long confluent forming lines and bands,

Figure 2. Dalbergia violacea. Wood (above) and charcoal (below) micrographs. — Scale bars: 100 μm.

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Figure 3. Stryphnodendron polyphyllum. Wood (above) and charcoal (below) micrographs. Scale bars: 100 μm.

Figure 4. Prismatic crystals in chambered fibres (wood, left) and in chambered parenchyma cells (charcoal, right) of Stryphnodendron polyphyllum. — Scale bars: 10 μm.

Downloaded from Brill.com10/06/2021 01:08:40PM via free access Gonçalves, Marcati & Scheel-Ybert — Carbonization of Brazilian woods 79 and diffuse; 1–4 cells per parenchyma strand. – Rays: 1- to 2-seriate, rarely 3-seriate; procumbent, square and upright cells mixed throughout the ray body. – Fibres: with simple to minutely bordered pits; non-septate; thick- to very thick-walled; gelatinous fibres present. –Storied structure: rays, axial parenchyma and vessel elements irregu- larly storied. – Secretory elements: absent. – Mineral inclusions: few prismatic crystals in non-chambered axial parenchyma cells.

Stryphnodendron polyphyllum (Fig. 3 & 4, Table 1) Growth rings: present, demarcated by thick-walled and radially flattened fibres; boundaries distinct in wood and charcoal. – Vessels: wood diffuse-porous; vessels solitary (62%) and in radial multiples of 2 (18%), 3 (12%) and 4 or more (7%); simple perforation plates; alternate intervessel pits, vestured; vessel-ray pits with distinct borders, similar to intervessel pits in size and shape throughout the ray cell. – Axial parenchyma: vasicentric to lozenge-aliform, short and long confluent; 2–6 cells per parenchyma strand. – Rays: 1-, rarely 2-seriate; all cells procumbent. – Fibres: with simple to minutely bordered pits; non-septate fibres present; mostly thin- to thick-walled, some very thick-walled; gelatinous fibres present. –Storied structure: absent. – Secre- tory elements: absent. – Mineral inclusions: prismatic crystals in axial alignments in chambered fibres and parenchyma cells.

Figure 5. Tapirira guianensis. Wood (above) and charcoal (below) micrographs. — Scale bars: 100 μm.

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Figure 6. Tapirira guianensis. Details of wood and charcoal anatomy. Radial canal, charcoal (a) and wood (b); Vessel- ray pits (c); Fused rays (d, arrow). — Scale bars: a & b = 30 μm; c = 10 μm; d = 100 μm.

Tapirira guianensis (Fig. 5 & 6, Table 1) Growth rings: present, demarcated by thick-walled and radially flattened fibres; boundaries distinct in wood and charcoal. – Vessels: wood diffuse-porous; vessels solitary (58%) and in radial multiples of 2 (24%), 3 (12%) and 4 or more (6%); tyloses rare; simple perforation plates; alternate intervessel pits; helical thickenings in some vessel elements; vessel-ray pits larger than intervessel pits, with much reduced borders to apparently simple, rounded, angular and horizontally elongate (gash-like to scalariform). – Axial parenchyma: scanty to vasicentric; 4–7 cells per parenchyma strand. – Rays: 1- to 3-seriate, mostly 3-seriate; body cells procumbent with 1 to 4 rows of upright and square marginal cells; rays with procumbent, square and upright cells mixed throughout the body may also occur. – Fibres: with simple to minutely bordered pits; septate and non-septate fibres present; mostly thin- to thick-walled; gelatinous fibres present. – Storied structure: absent. – Secretory elements: radial canals present. – Mineral inclusions: prismatic crystals mostly in upright and square marginal ray cells, few in procumbent cells.

Vochysia tucanorum (Fig. 7 & 8, Table 1) Growth rings: present, demarcated by lines or bands of marginal parenchyma; boundaries distinct in wood and especially in charcoal. – Vessels: wood diffuse-porous; vessels solitary (59%) and in radial multiples of 2 (32%), 3 (7%) and 4 or over (2%); tyloses present; simple perforation plates; alternate intervessel pits, vestured; vessel-ray

Downloaded from Brill.com10/06/2021 01:08:40PM via free access Gonçalves, Marcati & Scheel-Ybert — Carbonization of Brazilian woods 81 pits with distinct borders, similar to intervessel pits in size and shape throughout the ray cell. – Axial parenchyma: vasicentric and lozenge-aliform, short and long confluent, and in irregular marginal lines and bands; 2–6 cells per parenchyma strand. – Rays: 3- to 5-seriate; body cells procumbent with 1 to 2 rows of upright and square marginal cells. – Fibres: with simple to minutely bordered pits; non-septate fibres present; thick- walled; gelatinous fibres present. – Storied structure: absent. – Secretory elements: traumatic canals present. – Mineral inclusions: absent.

Figure 7. Vochysia tucanorum. Wood (above) and charcoal (below) micrographs. — Scale bars: 100 μm.

Figure 8. Vochysia tucanorum traumatic canals (wood, left; charcoal, right). — Scale bars: 100 μm.

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Figure 9. Pouteria torta. Wood (above) and charcoal (below) micrographs. — Scale bars: 100 μm.

Pouteria torta (Fig. 9, Table 1) Growth rings: present, demarcated by lines or bands of marginal parenchyma; boundaries fairly distinct in wood and charcoal. – Vessels: wood diffuse-porous, vessels in diagonal and/or radial pattern, solitary (29%) and in radial multiples of 2 (30%), 3 (23%) and 4 or more (17%); simple perforation plates; alternate intervessel pits; vessel-ray pits larger than intervessel pits, with much reduced borders to apparently simple, rounded, angular and horizontal to vertical; vessel-ray pits with distinct borders, similar to intervessel pits may also occur, as well as vessel-ray pits of two distinct sizes and types in the same ray cell. – Axial parenchyma: in lines and bands of 1–4 cells wide; 5–9 cells per parenchyma strand. – Rays: 1- to 2-seriate, mostly 1-seriate; body cells procumbent with up to 4 rows of upright and square marginal cells or procumbent, square and upright cells mixed throughout the ray body. – Fibres: with simple to minutely bordered pits; non-septate fibres present; thick-walled. – Storied structure: absent. – Secretory elements: absent. – Mineral inclusions: silica bodies in ray cells.

Discussion From the species here studied, only Tapirira guianensis had been previously described in the literature. Our anatomical description for this species is very close to previous studies of its wood (Mainieri 1958; Kribs 1968; Détienne & Jacquet 1983; Terrazas 1994; Richter & Dallwitz 2000; León & Williams 2003) and charcoal (Gonçalves 2006).

Downloaded from Brill.com10/06/2021 01:08:40PM via free access Gonçalves, Marcati & Scheel-Ybert — Carbonization of Brazilian woods 83 p 2 0.0855 0.0853 0.0881 0.0862 0.0891 p 2 indicates p 1 0.3520 0.3984 0.3227 0.3642 0.4084 3 5 5 6 2 3 5 7 5 5 2 6 8 6 6 S D

2 Charcoal 15 (11-19) 25 (18-28) 31 (21-39) 28 (20-34) 22 (14-31) 20 (16-25) 24 (11-32) 33 (25-40) 38 (28-48) 28 (24-39) 22 (10-29) 27 (23-30) 26 (14-45) 19 (10-29) 22 (17-33) vessels / mm –––––––––––––– 5 5 4 6 3 2 2 9 4 9 3 4 8 5 11 SD

2 Wood 17 (8-31) 20 (8-32) 13 (5-26) 17 (11-26) 23 (15-33) 25 (19-32) 15 (10-20) 15 (12-19) 28 (24-32) 40 (28-53) 21 (16-27) 30 (25-34) 18 (14-24) 23 (12-39) 21 (12-30) vessels / mm ––––––––––––––– p 2 0.0846 <0.0001 <0.0001 <0.0001 <0.0001 p 1 0.0075 0.0973 0.7472 0.0006 0.0009 0.0004 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 -8 -4 -2 -7 -12 (%) -26 -18 -32 -21 -17 -16 -17 -23 -23 -27

R eduction

9 9 9 11 11 21 14 16 13 13 10 12 18 14 15 SD Charcoal 71 (55-90) 49 (35-70) 68 (50-90) 76 (60-95) vessels ( µ m) 87 (60-115) 85 (65-120) 75 (60-100) 83 (65-110) 90 (65-125) 81 (60-100) 87 (60-125) 78 (55-120) 75 (60-100) 69 (50-105) 114 (75-140) 114 ø –––––––––––––––– 8 21 19 18 26 12 20 13 13 15 22 22 22 19 17 SD p 1 indicates the significance levels between wood and charcoal quantitative features among individuals, while Wood 50 (39-65) 73 (51-98) 91 (63-118) 91 (73-159) 98 (67-149) vessels ( µ m) 94 (60-155) 97 (72-147) 99 (67-132) 94 (68-136) 115 (88-159) 115 129 (92-156) 104 (81-127) 103 (67-139) 100 (76-141) 103 (60-145) ø ––––––––––––––––

3 2 1 3 2 1 3 2 1 3 2 1 3 2 1 Indiv.

violacea torta tucanorum guianensis polyphyllum Pouteria Vochysia Stryphnodendron Dalbergia

Tapirira

significance levels inside the species. Species Table 2. Quantitative anatomical data of the species analysed and statistical analysis. Table individual; SD: standard deviation; Indiv.:

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We compared the other species with generic or specific descriptions of the same genera using the specialized literature and the InsideWood database. Descriptions of Dalbergia (Pearson & Brown 1932; Kribs 1968; Détienne & Jacquet 1983; Quirk 1983; Dyer 1988; Nardi Berti & Edlmann Abbate 1992; Richter & Dallwitz 2000; PROTA 2002; Miller & Wiemann 2006; Gasson et al. 2010; Détienne, unpublished), Stryphno- dendron (Détienne & Jacquet 1983), Vochysia (Metcalfe & Chalk 1950; Kribs 1968; Pérez Olvera et al. 1980; Quirk 1980; Mogollon 1981; PADT-REFORT 1981; Nardi Berti & Edlmann Abbate 1992; Miller & Détienne 2001), and Pouteria (Metcalfe & Chalk 1950; Kribs 1968; Normand & Paquis 1976; Meylan & Butterfield 1978; Kukachka 1979, 1980, 1981, 1982; Pérez Olvera et al. 1980; Détienne & Jacquet 1983; Soerianegara & Lemmens 1993; Barajas-Morales et al. 1997; Miller & Détienne 2001; Lens 2005; Lemmens 2007a, 2007b, 2007c) are also pretty close to the ones presented above. Differences among descriptions concern presence of growth rings, tangential diameter of vessels, number of vessels per square millimetre, presence of tyloses, ray width, and cellular composition of rays, all of which commonly vary inside genera (Metcalfe & Chalk 1950; Carlquist 2001), and some of which are also influenced by ecological factors and water supply (Carlquist 2001; Schweingruber 2007). Vessel sizes were the wood features most affected by charring (Table 2). A significant reduction in tangential vessel diameter was observed in four out of five of the analyzed species. The average reduction was of 17%, varying from 2% in Tapirira guianensis (individual 2) to 32% in Vochysia tucanorum (individual 2). These results are related to the anisotropic behaviour of wood on its conversion into charcoal, with larger con- traction in the tangential direction (e.g. McGinnes et al. 1971; Prior & Gasson 1993; Kwon et al. 2009). For Quercus variabilis, a ring-porous wood, vessel shrinkage in the tangential direction was about 7.6 times greater than that of the radial direction at carbonization temperatures around 350–500 ºC (Kwon et al. 2009). Some individuals of Dalbergia violacea, Stryphnodendron polyphyllum, Vochysia tucanorum, and Pouteria torta showed a change in vessel outline from circular to angular after carbonization (Fig. 2, 3, 7, 9). A similar behaviour was observed in two species of Mimosa (Dias Leme et al. 2010). In spite of the significant reduction in tangential vessel diameter, there was no significant change in vessel frequency (Table 2), and no significant difference in the tangential diameter of intervessel pit apertures between wood and charcoal (Table 3). The ray frequency of all species and individuals analyzed was higher in charcoal (Table 3), but the differences were not significant. Significant changes in ray width occurred only in Stryphnodendron polyphyllum (individual 1) and Vochysia tucanorum (individuals 1 and 2), which showed narrower rays in charcoal than in wood (Table 3). In V. tucanorum this shrinkage was greater in larger rays, suggesting a possible tendency of higher shrinkage in larger rays. However, as we have not studied other large ray species, and there is no information available in the literature, more studies are still necessary to test this hypothesis. There were no significant changes in ray height between wood and charcoal in any individual analyzed. In contrast, an apparent reduction in ray height was detected in the species Stryphnodendron polyphyllum and Tapirira guianensis (Table 3). This

Downloaded from Brill.com10/06/2021 01:08:40PM via free access Gonçalves, Marcati & Scheel-Ybert — Carbonization of Brazilian woods 85 p 2 p 2 0.7541 0.2702 0.0009 0.7839 0.0046 0.0294 0.0002 <0.0001 <0.0001 <0.0001 2 indicates 2 p p 1 p 1 0.8116 0.7623 0.5120 0.7447 0.0923 0.5544 0.9281 0.9997 0.1333 0.1295 3 2 2 2 2 2 2 2 2 2 1 2 2 2 1 48 63 77 67 19 40 49 56 63 69 SD SD 127 164 126 150 162 Charcoal 7 (6-8) 6 (5-8) 6 (4-9) 9 (6-12) 8 (6-12) 9 (7-12) 12 (9-16) 10 (7-14) rays / mm 15 (11-17) 13 (10-17) 13 (10-16) 16 (12-20) –––––––––––––– 17 (12-21) 17 (13-20) 16 (12-19) Rays height 176 (92-292) 149 (89-224) 127 (90-255) 200 (114-372) 133 (110-180) 301 (250-400) 343 (195-600) 607 (250-910) 358 (180-586) 260 (170-365) 456 (260-750) 237 (130-330) 482 (320-760) 303 (215-370) 348 (220-445) 2 2 2 2 2 2 1 1 2 1 0 1 1 1 1 89 79 79 73 75 38 89 68 34 43 93 SD SD 117 192 155 342 Wood 7 (4-8) 4 (3-4) 5 (3-6) 4 (2-5) 8 (6-11) 7 (5-10) 11 (8-15) 11 8 (5-11) 9 (6-12) 9 (6-12) 13 (10-14) 14 (12-16) 13 (8-16) 14 (11-16) 13 (10-15) Rays height rays / mm 140 (99-218) –––––––––––––– 211 (120-375) 211 196 (110-310) 332 (232-535) 342 (216-502) 517 (316-959) 349 (200-620) 226 (160-400) 250 (135-389) 162 (105-226) 276 (172-450) 410 (200-535) 343 (270-400) 385 (261-531) 585 (347-1444) p 2 p 2 0.2166 0.0833 0.4401 0.0833 0.8871 0.9943 0.0833 0.0833 0.0833 <0.0001 p 1 p 1

0.9176 0.3679 0.3734 0.3184 0.0284 0.3679 0.2797 0.3169 0.2724 0.3679 0.3679 0.3679 <0.0001 <0.0001

1 7 6 1 6 6 1 1 1 7 4 3 1 1 3 3 6 3 8 4 1 1 1 1 1 1 1 1 11 12 S D S D pits Charcoal ø 5 (4-6) 6 (4-7) 6 (5-6) 5 (4-6) 5 (4-6) 5 (4-6) 5 (3-6) 4 (3-6) 6 (5-7) 5 (3-6) 5 (4-6) 2 (1-3) 4 (3-5) 5 (4-7) 6 (5-7) –––––––––––– 29 (15-50) 24 (15-35) 35 (25-45) 30 (20-42) 34 (25-40) 57 (40-75) 54 (45-70) 19 (15-25) 17 (10-20) 19 (15-25) 26 (20-30) 23 (15-30) 27 (20-30) 54 (45-70) 20 (15-25) 8 0 5 6 1 7 8 1 1 1 4 3 1 1 5 2 4 4 8 4 1 1 1 0 0 1 1 0 14 10 S d r ays width S D 1 indicates the significance levels between quantitative features of wood and charcoal among individuals, while individuals, among charcoal and wood of features quantitative between levels significance the indicates 1 p Wood pits ø 5 (4-6) 5 (5-7) 5 (3-6) 5 (4-6) 5 (4-6) 5 (4-6) 5 (4-7) 4 (3-5) 5 (4-8) 5 (4-7) 6 (5-6) 2 (2-3) 4 (3-5) 6 (5-7) 6 (5-7) –––––––––––– 26 (14-39) 23 (15-31) 31 (16-40) 30 (20-40) 39 (29-51) 57 (37-70) 19 (13-25) 20 (15-25) 17 (10-27) 29 (25-30) 22 (15-28) 26 (20-33) 73 (63-88) 18 (14-28) 74 (47-100)

3 3 1 2 1 1 3 1 3 2 2 3 2 1 2 1 3 1 2 3 1 2 3 3 2 3 1 2 1 2 Indiv. r ays width Indiv.

violacea violacea tucanorum polyphyllum guianensis polyphyllum guianensis tucanorum Species Dalbergia Dalbergia Stryphnodendron Stryphnodendron Tapirira Tapirira Vochysia Vochysia

Table 3. Quantitative anatomical data of the species analysed and statistical analysis. Table deviation; standard SD: individual; Indiv.: significance levels inside the species. Species

Pouteria torta

Downloaded from Brill.com10/06/2021 01:08:40PM via free access 86 IAWA Journal, Vol. 33 (1), 2012 variation cannot be assumed to be a consequence of the carbonization process, but is most probably due to natural differences in rays height among the three individuals sampled. Indeed, there is great interspecific and intraspecific variability of ray height, and this feature varies considerably inside individuals as well. These results, however, contrast to those obtained by Prior and Gasson (1993), who found significant reduction in ray height for all six African species they analyzed. Gelatinous fibres were found in most of the analyzed species, except in Pouteria torta (Table 1). Previous works reported that non-gelatinous fibres contract more than gelatinous ones (Prior & Alvin 1983; Prior & Gasson 1993), but this pattern was not observed in any of the species analyzed here. The qualitative analysis of fibres in wood and charcoal does not show any noticeable change. The same observation was made by Dias Leme et al. (2010). Carbonization did not damage wood structure in any of the studied samples. Gelati- nous fibres are as easily identifiable in charcoal as in wood. Radial and traumatic canals are very well preserved after charring, including the epithelial cells. Crystals and silica bodies are easier detectable in charcoal than in wood, due to light reflectance. Some wood features, as axial parenchyma, are frequently harder to observe in charcoal, but remain recognizable. On the other hand, Stryphnodendron polyphyllum parenchyma cells are more perceptible in charcoal than in wood. Among the studied species, charcoal of Tapirira guianensis showed the fewest modifications in cell dimensions. Species with large amounts of axial parenchyma showed a greater reduction in tangential vessel diameter, e.g.: Dalbergia violacea (21%), Vochysia tucanorum (20%), and Pouteria torta (19%). The same species also showed a higher deformation in vessel outline. We can hypothesize that the abundance of axial parenchyma might cause larger volumetric shrinkage in charcoal due to the thinner walls of the parenchyma cells. At the same time, none of the modifications found in the analyzed species prevent the correct identification of charcoal taxa.

Conclusions In all studied species, only small morphometric variations were observed in their wood anatomy. The wood and charcoal anatomy analyses demonstrate the preservation of qualitative structural features after carbonization at 400ºC. The main conclusions emerging from the analyses are: – Tangential vessel diameter reduced in four species. Only for Tapirira guianensis there was no significant variation in vessel diameter; – Vessels frequency showed little variability, with no significant statistical differences between wood and charcoal; – ray frequency increased in most of the individuals analyzed, but this trend was not statistically significant. – Ray width was significantly in only one out of three specimens ofStryphnodendron polyphyllum and two out of three specimens of Vochysia tucanorum; – Ray height showed no significant changes in any of the individuals analyzed.

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These conclusions corroborate the strong basis of anthracological identifications, as they demonstrate the close similarities of wood and charcoal anatomy.

Acknowledgments

This work is part of a MSc degree of the first author at the Universidade Estadual Paulista (Brazil). The authors are grateful to Dr Maria Aparecida Mourão Brasil (GAP/FAMESP, Universidade Estadual Paulista) and Dr Claudia Franca Barros (Instituto de Pesquisas Jardim Botanico do Rio de Janeiro) for helping with statistics and for the use of the scanning electron microscope, respectively, as well as for their useful comments and advice. We are also thankful to Dr. Pieter Baas for revision of the manuscript and helpful comments. This study was supported by grants from the CNPq (National Council for Scientific and Technological Development, Brazil) and FAPERJ (Research Foundation of the Rio de Janeiro State, Brazil). The first author benefited from a scholarship of FAPESP (Research Foundation of the São Paulo State, Brazil). The last author is a CNPq productivity scholarship holder.

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