Wood Anatomy of Three Lesser Known Species from Mozambique Ernesto Uetimane Junior1,2,*, Nasko Terziev1 and Geoffrey Daniel1 Th

IAWA Journal, Vol. 30 (3), 2009: 277–291

Wood anatomy of three lesser known species from Mozambique

Ernesto Uetimane Junior1,2,*, Nasko Terziev1 and Geoffrey Daniel1

SUMMARY Three lesser known wood species from Mozambique were studied to gen- erate information for identification purposes and facilitate the introduction of these species into the wood working industry by assigning or widening the potential uses of these species. Selected anatomical features were used to predict some important wood properties, subsequently confirmed by measurements of both density and impregnability. Comparative wood anatomy showed that all three wood species have anatomical features typical for their genus after comparisons with their closest relatives. Both ntholo (Pseudolachnostylis maprounaefolia Pax) and muanga (Pericop- sis angolensis Meeuwen) are diffuse-porous (with 14–24 and 16–20 vessels /mm2 respectively), have extractives in the heartwood vessels and thick-walled fibres, features consistent with good natural durability and strength respectively. Metil (Sterculia appendiculata K. Schum.) is also diffuse-porous with very wide vessels at much lower frequency 2 (< 5 /mm ), it lacks extractives in the heartwood vessels, and thin-walled axial and ray parenchyma constitutes the bulk of the ground tissue. This set of characteristics makes the wood light and satisfactory for construction purposes but highly vulnerable to biodegradation. Key words: Tropical hardwoods, Pericopsis angolensis, Pseudolachno- stylis maprounaefolia, Sterculia appendiculata, wood anatomy, wood properties.

INTRODUCTION

According to a national forest inventory (Marzoli 2007), about 70% (65.3 million ha) of Mozambique’s area is currently covered with forest (definition of FAO, FRA 2005), including some other types of woodland, all generally designated as miombo. The protected and conserved forest areas include about 14.4 million ha. The remaining woodlands contribute with up to 37% of the total forested area or 24 million ha. Recently, some authors (Ogle & Nhantumbo 2006; Ali et al. 2008) have addressed the need to explore the potential of lesser-known or lesser-used timber species in order not only to minimize pressure on the most sought species, but also to increase the productivity

1) Swedish University of Agricultural Sciences, Department of Forest Products/Wood Science, Box 7008, 750 07 Uppsala, Sweden. 2) Universidade Eduardo Mondlane, Departamento de Engenharia Florestal, CP 257 Maputo, Mozam- bique. *) Corresponding author [E-mail: [email protected]].

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 278 IAWA Journal, Vol. 30 (3), 2009 of the forest exploitation. Encouraging experience concerning studies of lesser known wood species in Africa was recently reported from Ghana (Ogle & Nhantumbo 2006; Oteng-Amoako 2006). In this context, a complete analysis was carried out in the 2007 Forest Inventory, in which some unknown and lesser used wood species were recorded, viz. Pseudolach- nostylis maprounaefolia Pax (ntholo), Pericopsis angolensis Meeuwen (muanga) and Sterculia appendiculata K. Schum. (metil). Ntholo is ranked amongst the most abundant wood species in the provinces of Zambézia, Tete, Cabo Delgado, and Manica, with 2% of the total volume of the national dense forest (FAO 2005 terminology) or 4.1 million m3. Earlier, Gomes e Sousa (1968) described this tree species botanically and emphasized its potential for common uses, especially for furniture and construction purposes, but no accounts about its wood anatomy, processing, and current uses were found. The authors also indicated that the trees are suitable for parks and gardens. Metil also accounts for 2% (i.e. about 4.1 million m3) of the total volume found in dense forest but its occurrence is mainly confined to the provinces of Cabo Delgado and Nampula. Muanga shares 3.4% (i.e. 1.9 million m3) of the standing volume available in open forests across Cabo Delgado, Zambézia, Manica and Sofala (Marzoli 2007). As in the case of ntholo, no data about the anatomy and processing of metil and muanga were found. This study is an attempt to contribute to the description of the wood anatomical features and to discuss the potential properties of the above mentioned species. Former studies correlating the wood structure and corresponding properties include Dinwoodie (1975); Ezell (1979); Leclercq (1980); Beery et al. 1983; Hillis (1989); Zhang & Zhong (1992); Lee et al. (2001); Perré & Badel (2003); Rahman et al. (2005); Bran- cheriau et al. (2006) and Wu et al. (2006). Some anatomical attributes commonly used to predict timber properties are fibre wall thickness, porosity pattern, fibre length, ground tissue proportions, microfibril angle and grain pattern. Despite recognized natural vari- ability in wood, structure-property relations from studies in the past have proved to be valid for many different wood species in such a way that many have become established theories with practical application in the field of wood science and technology. For example, the presence of extractives is associated with good natural durability and is an obstacle for fluid flow into wood, while high porosity and thin-walled fibres reflect low density. Thus, deriving properties from the structure is increasingly becoming reliable to the extent that foresters use this knowledge in silvicultural practice to produce trees with a set of desired wood properties. The present anatomical study was carried out in combination with a study of end- use properties of these three species, and we could therefore test the validity of some generally held views on structure-property relations.

MATERIAL AND METHODS Tree sampling Five trees of ntholo were felled and sampled at random within a stand as recom- mended for anatomical, physical and mechanical property studies (Pan American

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 279

Standard Commission, Co p a n t 1972). Due to technical difficulties, samples of both muanga and metil were taken from a sawmill in the same province (Cabo Delgado). It is assumed that these trees originated from approximately the same type of open forest and climatic conditions as the ntholo trees. Each tree was cut into three logs. The logs were sawn to 50-mm-thick planks. Samples for the anatomical study were taken from butt logs at breast height.

Site description Sampling took place in the northern province of Cabo Delgado, about 60 km from central Montepuez in an open dry forest stand frequently subjected to fires set by local people as a consequence of either shifting cultivation or traditional hunting activities. The climate of this region is mostly semi-arid, sub-humid and dry with an annual average precipitation ranging from 800 to 1000 mm and a temperature varying from 20 to 25 °C on average per year (Mozambique Ministry of State Administration, 2005). The geographical location of the ntholo stand is S 12° 15' 39.5" and E 39° 11' 57.4" (Fig. 1) and the stand altitude 376 m. In the sampling area, the trees are typically growing in association with bamboo (Fig. 2).

Microscopic observation and wood property measurements Sections used for light microscopic study were prepared after boiling small blocks of wood in water with 10% glycerin for 4 h. Afterwards the samples were rinsed and left in water overnight, but the blocks were still hard to section. Sections (20–40 µm

30°0'0"E 35°0'0"E 40°0'0"E

Congo, DRC Tanzania

10°0'0"S N

Zambia

Montepuez $ Pemba Lichinga Malawi $

Nampula Mocambique $ $ Mozambique 15°0'0"S

$Tele

$Quellmane Zimbabwe

$Chimolo Indian Ocean Beira $

0 75 150 300 20°0'0"S km = Sampling site

Figure 1. Sampling site location: Montepuez-Mozambique.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 280 IAWA Journal, Vol. 30 (3), 2009

Figure 2. Ntholo trees growing in dry open forest. thick) were cut using a Leitz sliding microtome. Some sections were stained either with 1% lactophenol blue (longitudinal sections) or 1% safranin (transverse sections). Anatomical features were described using terminology and procedures outlined in the IAWA Hardwood List (IAWA Committee 1989). Quantitative features like vessel density, vessel lumen diameter, number of rays, average tissue proportions, vessel element length including the tails, and fibre length were measured with the help of the software package Image-Pro Plus. Tissue proportions were measured from cross sections. Samples were delignified and macerated by treatment in a 1:1 mixture of 100% acetic acid and H2O2 under 60 °C for 18 hours (Wise et al. 1946) to allow vessel element and fibre length measurements. Scanning electron microscopy (SEM) was used to observe features like vestured pits and crystals. For SEM, semi-thin sections (i.e. TS, TLS, RLS) were air-dried, mounted on stubs, coated with gold and observed using a Philips XL30 ESEM at 15 kV (Daniel et al. 2004). The described features were compared with the wood anatomy of closely related taxa and subsequently used tentatively to predict or discuss potential wood properties as well as features that can hinder wood performance in common use.

Density and treatability Density at 12% moisture content was measured by the classical water displacement method. Standard procedures for impregnability tests were applied. The treatability was expressed as the ability of the wood samples to take up water under impregnation.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 281

Samples were subjected to a vacuum pressure of 60 mbar during 20 minutes followed by 8 bar pressure (30 min) and then kept in distilled water for 2 hours under atmospheric pressure. The amount of water retained in each sample was determined in kg/m3 by calculating weight differences (i.e. before and after impregnation).

Brief description of the trees Pseudolachnostylis maprounaefolia Pax (Euphorbiaceae, Ntholo) The trees are small, 5 to 10 m tall, with hemispherical crowns. The trunk is often about 30 cm in diameter and has a brown and cracked bark. The natural distribution of this species ranges from Central to East tropical Africa and in Mozambique ntholo grows on the northern Save River especially in plateau areas of open forest on sandy clay or frequently yellow soils (Gomes e Sousa 1968; Marzoli 2007).

Pericopsis angolensis Meeuwen (Leguminosae, Muanga) Muanga is a common tree growing both in the Brachystegia woodlands and wooded grassland within an altitude ranging from 500 to 1650 m. Muanga is mainly distributed across DRC, Zimbabwe, Tanzania and Mozambique (African Hardwoods n.d.). This species resembles Pericopsis elata found in West and Central Africa. Hyde and Wur- sten (2008b) reported muanga as mostly medium to large sized trees, with pale grey to whitish smooth bark and irregularly-shaped thin pieces peeling off the lower trunk. According to Dirninger (2004), muanga is a fast growing deciduous tree with a fairly open crown reaching 20 m in height with trunks 35 to 60 cm in diameter.

Sterculia appendiculata K. Schum. (Sterculiaceae, Metil) According to Hyde and Wursten (2008a), trees of this deciduous species have un- branched trunks and grow up to 40 m in height. The trunk diameter is 50 cm or more. The only branching is observed close to the crown. The bark is smooth, pale to yellowish grey and the young branchlets have dense woolly, rusty-yellow hairs. The natural distribution of this species is Malawi, Mozambique, Tanzania and Zimbabwe with the trees growing mainly in coastal and riverine forests (Hyde & Wursten 2008a).

RESULTS Wood anatomical descriptions Pseudolachnostylis maprounaefolia Pax (Ntholo) — Fig. 3 Growth ring boundaries indistinct to distinct; if present, marked by marginal parenchyma bands. Heartwood distinct. The grain is straight. Vessels diffuse, 18(14–24)/sq.mm, lumen diameter 108 (61–144) µm, solitary and in radial multiples of 2–4, rounded in TS (Fig. 3A); perforations simple, intervessel pits alternate and minute (4–5 µm), nonvestured (Fig. 3F). Vessel element length 765 (461–1099) µm. Vessel-ray pits similar to intervessel pits in shape and size. Gums and other deposits mixed with needle-like crystals present in the heartwood vessels (Fig. 3A, C: arrows).

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 282 IAWA Journal, Vol. 30 (3), 2009

Figure 3. Light (LM) and SEM micrographs of Pseudolachnostylis maprounaefolia (Ntholo). – A: Heartwood vessels filled with extractives (arrows). Extractives partly removed during sec- tioning (LM). – B: Rays at most 3 cells wide. Axial parenchyma strands of 4–8 cells (arrows) (LM). – C: Heartwood vessel containing needle-like crystals surrounded by extractives (SEM). – D: Chain of prismatic crystals in axial parenchyma (LM) (arrows). – E: Radial longitudinal section showing procumbent ray cells and square marginal cells (LM). – F: Minute intervessel pits (SEM). – G: Very thick-walled fibres with nearly occluded lumina (SEM). — Scale bars for A, B, D & E = 100 μm, C = 50 μm, F = 20 μm, G = 8 μm.

Fibres 2025 (1015–2533) µm long, very thick-walled, walls 6 (4–10) µm, with simple to minutely bordered pits mainly confined to the radial walls, nonseptate (Fig. 3G). Axial parenchyma in narrow, partly unilateral paratracheal bands, up to 4 cells wide (Fig. 3A), with 4–8 cells per strand (Fig. 3B). Both ray and axial parenchyma cells often filled with extractives (Fig. 3B, D). Rays 10 (5–15)/mm, 1–3-seriate and up to 650 µm tall (Fig. 3B, E), composed of square marginal cells and procumbent body ray cells. Prismatic crystals in chambered axial parenchyma, and in square marginal ray cells (Fig. 3D). Typically only one crystal of about the same size per cell or chamber (Fig. 3D: arrows).

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 283

Tissue proportions: ray parenchyma 22(19–24)%; axial parenchyma 8(7–9)%; vessels 14 (12–16)%; fibres 57 (53–60)% (Fig. 6).

Pericopsis angolensis Meeuwen (Muanga) — Fig. 4 The wood of muanga has distinct heartwood, straight grain, and indistinct to distinct growth ring boundaries. Vessels diffuse, 18 (16–20)/sq.mm, lumen diameter 131 (69–173) µm, solitary and in radial multiples of 2–4 (Fig. 4A). The outline of solitary vessels is rounded. Perfo-

Figure 4. Light (LM) and SEM micrographs of Pericopsis angolensis (Muanga). – A: Heart- wood vessels filled with yellowish brown extractives (arrows) (LM). – B: Very thick-walled fibres with occluded lumina (SEM). – C: Alternate intervessel pits (left arrow) and rays 3 cells wide (right arrow) (LM). – D: Small rays irregularly storied (LM). – E: Radial section showing procumbent ray cells (LM). – F: Alternate and vestured pits (SEM). — Scale bars for A, C, D & E = 100 μm, B & F = 10 μm.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 284 IAWA Journal, Vol. 30 (3), 2009 rations simple (Fig. 4A). Intervessel pits vestured, small to medium (4–9 µm wide), alternate (Fig. 4C, F). Vessel-ray pits with distinct borders, similar to intervessel pits in size and shape. Vessel element length 504 (379–664) µm. Gums and other deposits present in heartwood vessels (Fig. 4A: arrows). Fibres 2156 (1250–3000) µm long, very thick-walled, 9 (7–14) µm, with occluded lumina (Fig. 4B), with simple to minutely bordered pits, non-septate.

Figure 5. Light (LM) and SEM micrographs of Sterculia appendiculata (Metil). – A: Large vessels in very low frequency (< 5/mm2). Broad bands of axial parenchyma, and small blocks of thick-walled fibres (LM) (arrows). – B: Sheath cells (arrows) in multiseriatre rays (LM). – C: Very thin-walled axial parenchyma cells and intercellular spaces (LM). – D: Prismatic crystals (arrows) in chambered axial parenchyma (LM). – E: Procumbent and upright ray cells in radial section (LM). – F: Intervessel pitting (SEM). — Scale bars for A–E = 100 μm, for F = 50 μm.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 285

Axial parenchyma, winged-aliform to confluent and in up to 5 cells wide discontinu- ous paratracheal bands, in 3–4 cells per strand, storied with the vessel elements. Rays 6 (4–14)/mm, 1–3-seriate, 434 (240–950) µm tall, composed of procumbent central cells with one row of square to upright marginal cells (Fig. 4E): small rays irregularly storied (Fig. 4C, D). Prismatic crystals rarely observed in chambered parenchyma on the border of axial parenchyma and fibre tissue. Silica bodies were not observed. Tissue proportions: ray parenchyma 17 (14–20)%; axial parenchyma 7 (5–9)%; vessels 19 (17–20)%; fibres 58 (51–64)% (Fig. 6).

Sterculia appendiculata K. Schum. (Metil) — Fig. 5 The wood has a straight grain and the growth ring boundaries are indistinct. Heart- wood and sapwood are indistinguishable at the macroscopic level. Vessels diffuse, 3 (1–4)/sq.mm, lumen diameter 371 (195–527) µm, solitary or in radial pairs, rounded and oval in TS, perforations simple, intervessel pits alternate, 8–10 µm in diameter (Fig. 5A, F). Vessel-ray pits with reduced borders to simple and similar to the intervessel pits in size and shape. Vessel element length 489 (298–583) µm. Tyloses, gums or other deposits absent from the heartwood vessels. Fibres 2220 (1500–2750) µm long, thick-walled 6 (4–9) µm, in bands that are narrower than the very broad axial parenchyma bands (Fig. 5A, B). Ground tissue fibres with simple to minutely bordered pits. Axial parenchyma in 3–20 cells wide bands, in strands of 3–4 cells, storied (Fig. 5B). Prismatic crystals in both chambered and non-chambered axial parenchyma cells (Fig. 5D: arrows). Rays 1–4(–3)/mm, 3–17-seriate, 1429 (500–3000) µm tall, composed of procumbent central cells, with 1–4 rows of square to upright marginal cells, and surrounded by sheath cells (Fig. 5B, E). Tissue proportions: ray parenchyma 19 (13–24)%; axial parenchyma 53 (50–61)%; vessels 6 (0–13)%; fibres 22 (17–27)% (Fig. 6).

Ground tissue proportion 70

60 Ntholo 50 Muanga Metil 40

20 Average Average composition (%)

0 Ray Axial Vessels Fibres parenchyma parenchyma

Tissues Figure 6. Average tissue proportions for the three timber species.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 286 IAWA Journal, Vol. 30 (3), 2009

DISCUSSION Comparison with related taxa Pseudolachnostylis According to Mennega (1987), the genera Pseudolachnostylis and Securinega belong to the subtribe Securineginae Muell. Arg. of the family Euphorbiaceae. Thus, wood anatomy descriptions of Securinega durissima (bois dur) available on the InsideWood database were compared with that of Pseudolachnostylis maprounaefolia. Both species are diffuse-porous with vessels solitary and in radial multiples, although vessels of Securinega durissima are occasionally disposed in a diagonal pattern and are smaller in diameter. Vessel element length is of the same range. Securinega durissima has a higher vessel density (40–100/sq. mm) than Pseudolachnostylis maprounaefolia (14–24/sq. mm). Similar features include intervessel pit shape and size, vessel-ray pits, fibre pits, non-septate fibres, mean fibre length range, and very thick-walled fibres. The axial parenchyma of P. maprounaefolia differs from that of S. durissima which is diffuse or in irregular bands of only one cell wide. Ray features are similar and prismatic crystals are present in chambered axial parenchyma and in marginal square ray cells of both species. All these similarities confirm the close phylogenetic affinities of Securinega and Pseudolachnostylis (Wurdack et al. 2004).

Pericopsis angolensis & P. elata Wood anatomy of muanga is compared with that of its closest sister within the genus Pericopsis, i.e. Pericopsis elata (Harms) Meeuwen (Kokrodua), described by Richter and Dallwitz (2000) and available in the InsideWood database. Pericopsis elata is a CITES-listed species in Annex II, growing in West Africa and its wood anatomy is very similar to Pericopsis angolensis from Central and East Africa (UNEP-WCMC 2008). This can be easily inferred by comparing wood anatomical features of the two species. Virtually all wood anatomical features overlap or are identical. Small differences include vessel element length (reputedly shorter in P. elata), parenchyma distribution (greater tendency for banding in P. angolensis); prismatic crystals are found in slightly different patterns, i.e. in P. angolensis this trait is mainly observed on the border of axial parenchyma and fibre tissue while in P. elata they occur either in ray cells or in chambered axial parenchyma cells.

Sterculia appendiculata & S. comorensis Sterculia comorensis is a tree species growing in Madagascar, Mauritius, Réunion, and Comores, and its wood has been described by Détienne (unpublished, but data available on the InsideWood database website). The wood anatomy of these two species is very similar. The similarity extends to the lack of tyloses, gums or other deposits in heartwood vessels. The fibres are thin- to thick-walled in S. comorensis, but only very thick-walled in its counterpart, S. appendiculata. Chambered prismatic crystals are present in both species, but occur in both ray and axial parenchyma in S. comorensis, and are restricted to axial parenchyma in S. appendiculata. Metil is clearly within the range of wood anatomical variation of the species-rich genus Sterculia (cf. Chattaway 1937).

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 287

Table 1. Selected anatomical features related to properties of wood for Pericopsis angolensis, Pseudolachnostylis maprounaefolia and Sterculia appendiculata.

Wood species

Anatomical features P. maprounaefolia P. angolensis S. appendiculata (Ntholo) (Muanga) (Metil) Grain Straight Straight Straight Vessel diameter range (μm) (61–)108(–144) (69–)131(–173) (195–)371(–527) n = 33, sd = 21 n = 47, sd = 23 n = 36, sd = 78 Fibre length range (μm) (1015–)2025(–2533) (1250–)2156(–3000) (1500–)2220(–2750) n = 31, sd = 418 n = 32, sd = 346 n = 33, sd = 329 Vessel density / mm2 (14–)18(–24) (16–)18(–20) (1–)3(–4) n = 350 n= 333 n = 110 Ray width in cells 1–3 1–3 (1–)10(–17) Extractives in heartwood vessels Present (yellowish) Present (brownish) Not observed Volume % of thick-walled fibres 57 58 22 Fibre wall thickness (μm) Very thick-walled Very thick-walled Very thick-walled (4–)6(–10) (7–)9(–14) (4–)6(–9) n = 25, sd = 1.4 n = 29, sd = 1.5 n = 41, sd = 1.3

Anatomical features and wood properties Table 1 summarises selected features from which timber properties can be tentatively predicted. Apparently, all three species have a straight grain allowing a smooth surface of wood upon sawing and planing. Ntholo and muanga have similar features, e.g. vessel density (Table 1), presence of gums, extractives and a high volume percentage of very thick-walled fibres (Fig. 6). This suggests that both wood species have a low permeability and are naturally durable due to the presence of extractives (Table 2). Ntholo and muanga contain 57–58% of very thick-walled fibres combined with a relatively small tangential vessel diameter range (61–144 and 69–173 µm) compared to metil’s 22% fibres and much larger vessel diameter range (195–527µ m) (Table 1). The above mentioned features are prerequisites for the significantly higher density of ntholo and muanga compared to that of metil (Table 2) and consequently a higher mechanical strength can be predicted (Ezell 1979; Akachuku 1985; Bowyer et al. 2003). Moreover, large diameter wood vessels and thin-walled parenchyma are known to lower the strength of the wood, i.e. features shown by metil. The overall tissue proportions are almost identical for both ntholo and muanga (Fig. 6), thus suggesting very similar physical-mechanical properties and behaviour under timber processing. Metil is ecologically well-adapted for efficient water transport since it has wide vessels but very low vessel density (< 5/mm2) (Table 1). In contrast, ntholo and muanga show a hydraulic architecture in terms of vessel density and diameter that is better

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 288 IAWA Journal, Vol. 30 (3), 2009

Table 2. Measured and predicted wood properties.

Mean values of some wood Ntholo Muanga Metil properties and drying Density (12% MC) Very high Very high Low (kg/m3) (950) (941) (463) Treatability (heartwood retention) Extremely difficult Difficult Easy to treat (kg/m3) (43) (110) (463) Drying Slow Slow* Fast* (D = 2.49 E - 10 m2/s) Natural durability Very durable* Very durable* Slightly to non-durable* * Predicted properties. D = Diffusion coefficient measured through non-symmetrical drying test at 60 °C and 25 % relative humidity. adapted to hydraulic safety required in dry environments (Zimmerman 1983; Baas et al. 2004; Wheeler et al. 2007). Metil has a high volume percentage of axial parenchyma and wide vessels lacking extractives. The wood is lighter, probably very vulnerable to biodegradation by fungi and insects, but possessing a high impregnability (Table 2). Sterculia pruriens growing in Venezuela proved to be non durable under both laboratory soft rot tests and in ground contact trials (Castro-Medina et al. 2008; Márquez et al. 2008). Metil has many wide rays (10-seriate or more), however allowing rapid drying (although prone to radial splitting) compared to both muanga and ntholo with much narrower rays (Bowyer et al. 2003). Preliminary results (Uetimane et al. 2008 unpublished data) regarding the drying behaviour of ntholo confirmed that this species requires a long drying pe- riod since its calculated diffusion coefficient is 2.49 E-10 m2/s, i.e. a value close to other tropical and temperate hardwood species known as slow drying species, namely eucalyptus (Eucalyptus tereticornis), cherry (Prunus avium) and niangon (Tarrietia utilis). In this respect, muanga is likely to have the same drying behaviour as ntholo given its similarity in density. Hardwood fibre lengths are generally known to be shorter than those of softwoods. Thus, softwood fibres are more desirable for pulp and paper (Bowyer et al. 2003). Ntholo, muanga and metil have average fibre lengths of 2025, 2156 and 2220 µm respectively, values much lower than average softwood fibres of 3000 to 4000 µm, but still at the long end of the fibre length range in hardwoods.

CONCLUSIONS

In general, the structure of the selected lesser-known wood species from Mozambique revealed promising properties for diverse end uses. Specifically, ntholo and muanga may be interchangeable and be assigned to uses where mechanical strength and natu-

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 289 ral durability are important. In contrast, the structure of metil suggested a light wood with poor natural durability, though with good prospects if impregnated (i.e. few but wide vessels). Additionally, the drying rate of metil is likely to be significantly higher compared to both muanga and ntholo. In terms of end uses, metil is thought suitable for veneer production due to the absence of extractives within the heartwood vessels.

ACKNOWLEDGEMENTS

Thanks are due to the Swedish International Development Agency (SIDA), particularly the Depart- ment for Research Cooperation (SAREC) and Eduardo Mondlane University (UEM) for funding the research project of which this study forms part. The authors also thank Pieter Baas for revision of the manuscript and Ann-Sofie Hansén for microscopic slide preparation.

REFERENCES

Ali, A.C., E. Uetimane, I.A. Lhate & N. Terziev. 2008. Anatomical characteristics, properties and use of traditionally used and lesser known wood species from Mozambique – a literature review. J. Wood Sci. & Technol. 42: 453–472. African Hardwoods. http://www.zanzibarconnection.com/specs.html [Accessed: 27/02/08]. Akachuku, A.E. 1985. The effects of some extrinsic and intrinsic factors on the proportions of vessels in Gmelina arborea Roxb. J. Wood Sci. & Technol. 19: 1–12. Baas, P., F.W. Ewers, S.D. Davis & E.A. Wheeler. 2004. Evolution of xylem physiology. In: I. Poole & A. Hemsley (eds.), Evolution of plant physiology: 273–295. Linnaean Society Symposium Series. Elsevier Academic Press, London. Beery, W.H., G. Ifju & T.M. McLain. 1983. Quantitative wood anatomy – Relating anatomy to transverse tensile strength. Wood and Fiber Science 15 (4): 395–407. Bowyer, J.L., R. Shmulsky & J.G. Haygreen. 2003. Forest products and wood science: an introduction. Ed. 4. 554 pp. Brancheriau, L., H. Baillères, P. Détienne, J. Gril & R. Kronland. 2006. Key signal and wood anatomy parameters related to the acoustic quality of wood for xylophone-type percussion instruments. J. Wood Sci. 52: 270–273. Castro-Medina, F., A. Márquez, L. Gómez & J. Velásquez. 2008. Wood biodegradation of forest species of the Venezuelan Guayana. In: 14th International Biodeterioration & Biodegradation Symposium 6-11 October 2008, Messina, Italy. Poster 112. IBBS-14. Chattaway, M.M. 1937. The wood anatomy of the family Sterculiaceae. Phil. Trans. Roy. Soc. Lond. B. 228: 313–366. Co p a n t . 1972. Norma Pan Americana. Maderas. Selección y colección de muestras. Commission Pan Americana de Normas Técnicas. Buenos Aires, Argentina. Daniel, G., I. Duchesne, C. Tokoh & S. Bardage, 2004. The surface and intracellular nanostructure of wood fibres: Electron microscope methods and observations. In Proceedings of COST Action: Wood Fibre Cell Walls: Methods to study their formation, structure and properties. 87–104. Eds. U. Schmit, P. Ander, J.C. Barnett, A.M.C. Emmons, G. Jeromidis, P. Saranpää, S. Tschegg (Available at http://www-wurc.slu.se). Détienne, P. (no date). Woods of Madagascar. CIRAD unpublished (Available at http://Inside- Wood.lib.ncsu.edu/search). Dinwoodie, J.M. 1975. Timber – a review of the structure-mechanical property relationship. J. Microscopy 104: 3–32.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access 290 IAWA Journal, Vol. 30 (3), 2009

Dirninger, P. 2004. Indicators and tools for restoration and sustainable management of forest in East Africa. ITTO working paper No. 25. University of Natural Resources and Applied Life Sciences, Vienna. Ezell, A.W. 1979. Variation of cellular proportion in Sweetgum and their relation to other wood properties. Wood and Fiber Science 11 (2): 136–143. FAO. 2005. Global Forest Resources Assessment. Forestry Paper 147. Annex 2. Terms and defi- nitions for national reporting tables for FRA 2005. Rome. Gomes e Sousa, A. 1968. Dendrologia de Mocambique. Vol. 1 & 2. Hillis, W.E. 1989. Structure-property relationships of wood as they affect end use: 13–24. The Second Pacific Regional Wood Anatomy Conference, Philippines. Hyde, M. & B. Wursten. 2008a. Sterculia appendiculata K. Schum. http://www.zimbabweflora. co.zw/speciesdata/species.php. Last modified: 24 February 2008 [Accessed: 27/02/2008]. Hyde, M. & B. Wursten. 2008b. Pericopsis angolensis. http://www.zimbabweflora.co.zw/species data/species.php. Last modified: 4 May 2008 [Accessed: 24/06/2008]. IAWA Committee. 1989. IAWA List of microscopic features for hardwood identification. Leiden, The Netherlands. InsideWood. 2004-onwards. Published on the internet. http://insidewood.lib.ncsu.edu/search [Accessed: 17/09/2008]. Leclercq, A. 1980. Relationship between beechwood anatomy and its physico-mechanical properties. IAWA Bull. n.s. 1/2: 65–71. Lee, B.J., A.G. McDonald & B. James. 2001. Influence of fiber length on the mechanical properties of wood-fiber/polypropylene prepeg sheets. J. Material Research Innovation 4: 97–103. Springer-Verlag. Márquez, A., F. Castro-Medina, L. Gómez & J. Velásquez. 2008. Natural durability of hardwoods in Venezuela. In: 14th International Biodeterioration & Biodegradation Symposium 6-11 October 2008, Messina, Italy. Poster 118. IBBS-14. Marzoli, A. 2007. Inventário Florestal Nacional. Direcção Nacional de Terras e Florestas. Draft final, Maputo, Moçambique. Mennega, A.M.W. 1987. Wood anatomy of Euphorbiaceae, in particular of the subfamily Phyl- lanthoideae. Bot. J. Linn. Soc. 94: 111–126. Ministry of State Administration. 2005. Montepuez District Profile. Cabo Delgado Province. Republic of Mozambique. Ogle, A. & I. Nhantumbo. 2006. Improving the competitiveness of the timber and wood sector in Mozambique. USAID, Maputo, Mozambique. Otengo-Amoako, A.A. (ed.). 2006. 100 Tropical African timber trees from Ghana. Tree description and wood identification with notes on distribution, ecology, silviculture, ethnobotany and wood uses. Forestry Research Institute of Ghana, Department of Publishing Studies, KNUST, Kumasi. Perré, P. & É. Badel. 2003. Predicting of oak wood properties using X-ray inspection: representa- tion, homogenization and localization. Part II: Computation of macroscopic properties and microscopic stress fields. INRA, EDP Sciences. Annals of Forest Sciences 60: 247–257. Rahman, M.M., S. Fujiwara & Y. Kanagawa. 2005. Variations in volume and dimensions of rays and their effect on wood properties of teak. Wood and Fiber Science 37 (3): 497–504. Richter, H.G. & M.J. Dallwitz (2000 onwards). Commercial timbers: descriptions, illustrations, identification, and information retrieval. In English, French, German, and Spanish. Version 16 April 2006. http://delta-intkey.com. Uetimane, E., O. Allegretti & N. Terziev. 2008. Drying behaviour of ntholo (Pseudolachnostylis maprounaefolia Pax) (Manuscript).

Downloaded from Brill.com10/08/2021 09:06:48PM via free access Uetimane, Terziev & Daniel — Timbers from Mozambique 291

UNEP-WCMC. 2008. Species database: CITES-listed species. Accessed on 18 September 2008. Wheeler, E.A., P. Baas & S. Rodgers. 2007. Variations in dicot wood anatomy: A global analysis based on the Insidewood database. IAWA Bull. n.s. 28: 229–258. Wise, L.E., M. Murphy & A.A. D’Addieco. 1946. Chlorite holocellulose, its fractionation and bearing on summative wood analysis and on studies on the hemicelluloses. Paper Trade J. 122: 35–43. Wu, Y.Q., K. Hayashi, Y. Liu & Y.C.M. Sugimori. 2006. Relationship of anatomical characteristics versus shrinkage and collapse properties in plantation-grown eucalypt wood from China. J. Wood Sci. 52: 187–194. Wurdack, K.J., P. Hoffmann, R. Samuel, A. de Bruijn, M. van der Bank & M.W. Chase. 2004. Molecular phylogenetic analysis of Phyllanthaceae (Phyllanthoideae pro parte, Euphorbiaceae sensu lato) using plastid rbcL DNA sequences. Amer. J. Bot. 91: 1882–1900. Zhang, S.Y. & Y. Zhong. 1992. Structure-properties relationship of wood in East-Liaoning oak. Wood Sci. & Technol. 26: 139–149. Zimmerman, M.H. 1983. Xylem structure and the ascent of sap. Springer-Verlag, New York.

Downloaded from Brill.com10/08/2021 09:06:48PM via free access