Changes

'''== Trade groups'''==

*'''Balau''': heavy hardwood, e.g. ''Shorea laevis'' Ridley, ''S. materialis'' Ridley, ''S. maxwelliana'' King and ''S. scrobiculata'' Burck.

*'''Red balau''': heavy hardwood, e.g. ''S. collina'' Ridley, ''S. guiso'' (Blanco) Blume and ''S. kunstleri'' King.

The timber of some species (e.g. ''S. elliptica, S. kunstleri'' ) is either traded as red balau or red meranti, depending on the density of the wood. Hence, the distinction between those trade groups is not sharp.

*'''Balau'''*Balau. Brunei: selangan batu

*'''Red balau. '''*Brunei: red selangan, selangan merah

The fruits of many species can be boiled and eaten (mainly as famine food). A few species yield fruits from which a fat similar to cocoa butter is obtained (e.g. ''S. seminis'' ). It is used in Europe for manufacturing chocolates and cosmetics and was formerly used in soaps, candles and tallow. The fruits are often called "illipe nuts" which sometimes leads to confusion with the illipe nut from ''Madhuca'' spp. ( ''Sapotaceae'' ).

The bark and wood of some species (e.g. ''S. robusta'' Gaertner f., ''S.'' ''obtusa'' and ''S. siamensis'' ) contains tannin.

No export figures for balau and red balau are available for Indonesia. The export of sawn balau timber from Peninsular Malaysia peaked in 1987 with 47 500 m³(worth US$ 6.4 million) falling to 27 000 m³(worth US$ 4.9 million) in 1990, and 17 500 m³(worth US$ 3.8 million) in 1992. In Peninsular Malaysia the price of exported sawn balau timber was US$ 115/m³in 1984 and US$ 220/m³in 1992. The export of sawn timber of red balau increased in Peninsular Malaysia from only 2400 m³(with a value of US$ 400 000) in 1983 to 12 000 m³(worth US$ 2.5 million) in 1989; in 1990 the export was 10 500 m³(worth US$ 1.8 million), and in 1992 5000 m³(worth US$ 1.2 million). The export of balau and red balau is more important in eastern Malaysia. In 1987 export of round logs of balau from Sabah was 526 000 m³(with a value of US$ 37.8 million), and of red balau was 33 000 m³(with a value of US$ 2.2 million); in 1992 the export of balau logs was 90 000 m³and of sawn timber 292 000 m³(with a total value of US$ 93 million), and the export of red balau logs was 12 500 m³and of sawn timber 750 m³(with a total value of US$ 1.5 million).

Balau is a heavy hardwood. The heartwood is yellowish- to reddish-brown when freshly cut, changing to red-brown, purple-brown or dark brown on exposure. The heartwood is moderately distinct from the sapwood, which is lighter and yellowish- to reddish- or purplish-brown. The radial section shows a stripe figure, the end surface shows a metallic lustre and is variably glossy. The density is (600-)850-1160 kg/m³at 15% moisture content. The grain of the wood is straight to spiral or interlocked, texture moderately fine to moderately coarse and even.

The rates of shrinkage are high when compared, for instance, to the otherwise very similar chengal ( ''Neobalanocarpus heimii'' (King) P. Ashton): from green to 15% moisture content 1.5-2.7% radial and 3.1-3.9% tangential, and from green to oven dry c. 4.2% radial and 9.3% tangential. Balau dries slowly with moderate to severe end checks and slight to severe splits; surface checks are moderate but the timber does not warp. The air drying of 15 mm and 40 mm thick boards takes about 4 months and 10 months, respectively. In Malaysia kiln-drying schedule B is recommended.

Red balau is also a heavy hardwood. The heartwood is light to dark red-brown or purplish-red, darkening on exposure and losing much of its red colour, fairly distinct from the lighter sapwood (pink, greyish-brown). Planed surfaces occasionally show a stripe figure. The density is generally somewhat less than that of balau: (675-)750-880(-1090) kg/m³at 15% moisture content. The grain of the wood is deeply interlocked, texture moderately fine to slightly coarse and even. Generally speaking, red balau is slightly inferior to balau in mechanical properties and durability, but it is markedly superior to dark red meranti. At 55% moisture content the modulus of rupture is 84-105 N/mm², modulus of elasticity 13 700-19 000 N/mm², compression parallel to grain 43-58 N/mm², compression perpendicular to grain 5.5-9.5 N/mm², shear 9.5-10.5 N/mm², cleavage 67-75 N/mm radial and 77-93 N/mm tangential, and Janka side hardness 4490-6940 N.

Red balau is usually easier to work than balau but the working qualities are rated as slightly difficult. It is slightly difficult to difficult to saw, but planing is easy, giving a smooth to slightly rough finish. Boring is easy to slightly difficult and turning is easy to difficult. The nailing property is rated from poor (for ''S. kunstleri'' ) to good ( ''S. guiso'' and ''S. ochrophloia'' ).

*Medium-sized to very large trees up to 60(-75) m tall; bole straight, cylindrical, branchless for 6-25(-40) m and with a diameter of up to 180(-300) cm; buttresses prominent, up to 5 m high and very thin, growing away from the bole more or less spirally; bark surface longitudinally cracked or square-section fissured and usually flaky, shedding in thin, flat scales, grey, red or brown, outer bark usually comparatively thin, inner bark yellowish to greenish-yellow or red, exuding a clear, sticky, pale yellowish or brownish resin; crown hemispherical or dome-shaped, sympodial. *Leaves alternate, simple, entire, glabrous, pinnately veined with scalariform tertiary venation, often glaucous on the lower surface; stipules and bracts small, fugaceous. *Inflorescences terminal or axillary, paniculate. *Flowers secund or distichous, bisexual, 5-merous, actinomorphic, scented; calyx lobes free, hirsute; petals free or connate at base, cream, often pink at base, the outer surface hirsute; stamens 15-60, the anthers with 4 pollen sacs, usually broadly oblong, both the appendages and pollen sacs usually barbate; ovary surmounted by a stylopodium, tomentose, style usually shorter than the ovary. *Fruit usually shortly stalked with the outer 3 or rarely all calyx lobes much elongated, these more or less thickened at base and saccate, sometimes all calyx lobes short and subequal; nut 1-seeded, free from the calyx, subglobose to ovate, with a long beak. *Seedling with epigeal germination; pericarp splitting irregularly; cotyledons reniform-sagittate, greenish-orange or red; first two leaves opposite, subsequent leaves arranged spirally, often larger than those on mature trees.

*Heartwood yellowish- to reddish-brown when freshly cut, darkening to dark brown or dark purplish-brown on exposure, moderately distinctly demarcated from the lighter sapwood (yellowish-, red- or purplish-brown). *Grain straight, spiral or interlocked. *Texture varying from fine to coarse, generally moderately coarse to coarse; quarter-sawn surface often with a stripe figure, end grain shiny with a metallic lustre. *Growth rings absent, but the long tangential bands of resin canals with white contents and the parenchyma associated with them may have the appearance of growth rings; vessels fairly evenly distributed, but with a tendency to form short, oblique lines mostly filled with tyloses, but without deposits, visible to the naked eye; parenchyma not distinct without a lens; rays visible to the naked eye but not conspicuous on the radial surface, containing brown deposits. *Ripple marks mostly absent.

*Growth rings absent. *Vessels diffuse, 2-10(-14)/mm², mostly solitary but also in radial or oblique multiples of 2-4, round to oval, with a tangential diameter of 75-300μm300 μm; perforations simple; intervessel pits alternate, dense and vestured, with an average diameter of 5-7μm7 μm; vessel-ray and vessel-parenchyma pits large, round or gash-like, simple; helical thickenings absent; vessels mostly filled with tyloses. *Fibres 900-1600μm 1600 μm long, 14-16μm 16 μm in diameter, non-septate, walls 5-7μm 7 μm thick, pits minutely bordered, largely confined to the radial walls. *Parenchyma scarce to moderately abundant, occasionally abundant (e.g. in ''S. exelliptica'' , ''S. falciferoides'' , ''S. foxworthyi'' ), mainly paratracheal consisting of narrow incomplete sheaths around the vessels, often distinctly aliform (e.g. in ''S. laevis'' ), but sometimes (locally) confluent; apotracheal parenchyma diffuse and diffuse-in-aggregates or as concentric bands containing the vertical resin canals, as occasional terminal bands, and as short fine lines of varying widths. *Rays 5-12/mm, mostly multiseriate, 3-4(-5)-seriate and frequently under 30 cells high (350-650μm650 μm); uniseriate margins of rays typically only 1 or 2 cells high, with occasional margins 3-4 cells high; most of the rays similar (usually Kribs type heterogeneous II-III, rarely homogeneous). *Crystalliferous axial parenchyma strands and/or ray cells with solitary prismatic crystals usually abundant. *Silica bodies absent. *Intercellular canals smaller than vessels and arranged in long or short concentric (tangential) bands filled with white resin.

Species studied: ''S. astylosa'' , ''S. ciliata'' , ''S. exelliptica'' , ''S. falciferoides'' , ''S. foxworthyi'' , ''S. glauca'' , ''S. havilandii'' , ''S.'' ''inappendiculata'' , ''S.'' ''laevis'' , ''S.'' ''lumutensis'' , ''S.'' ''malibato,'' ''S.'' ''maxwelliana,'' ''S.'' ''scrobiculata,'' ''S.'' ''seminis,'' ''S.'' ''submontana'' , ''S.'' ''superba'' .

Optimal growth of seedlings of ''S. materialis'' in terms of increases in height, stem diameter, leaf area and overall dry matter was observed between 30-55% relative light intensities. Seedling growth of ''S. laevis'' is best under moderate shading and is considerably better than when grown in full sunlight or under heavy shading. As in all dipterocarps, mycorrhizae are essential for good growth. Research in the forest understorey showed that 42% of ''S. maxwelliana'' seedlings had no ectomycorrhizae. Infected seedlings are taller than seedlings without ectomycorrhizae. Once established, balau saplings are able to persist for a number of years in the understorey under heavy shade, but they need moderate to high light intensities for rapid growth. Balau-producing species grow slowly. Annual diameter growth of ''S. siamensis'' in Thailand is reported to be only 1-2 mm. In Peninsular Malaysia planted trees of ''S. geniculata'' and ''S. scrobiculata'' reached bole diameters of only 27 cm and 18 cm respectively in 40 years. The red balau ''S. guiso'' grows considerably faster; the annual girth increment of this species was 1.6-2.0 cm in Peninsular Malaysia. Other red balau-producing species also grow comparatively fast, e.g. ''S. kunstleri'' and ''S. ochrophloia'' , which may reach a bole diameter of 55 cm in 40 years. Large balau trees can be very old, several hundreds of years at least.

Regrowth from stumps does occur after coppicing, e.g. in ''S. siamensis'' . The best coppicing power is found in small trees (up to 20 cm in diameter). Coppice shoots grow well. Coppicing may be applied for firewood production.

Anatomical features of the wood and bark provide useful evidence for the classification of species at infrageneric level. The division of the genus ''Shorea'' into 4 major timber groups (red meranti, white meranti, yellow meranti, and balau and red balau) coincides in broad outline with the division of the genus into botanical sections. Timbers of the balau group belong to the sections ''Shorea'' and ''Neohopea'' P. Ashton. The section ''Pentacme'' (A.DC.) P. Ashton contains two species, ''S. siamensis'' and ''S. contorta'' S. Vidal. The first is classified as a balau; the second, however, is classified as a light red meranti, white meranti or a white lauan (this being the timber trade name for species of the genus ''Parashorea'' ). The section ''Pentacme'' is botanically rather aberrant from the other sections.

Timber of the red balau group originates mostly from species in section ''Shorea'' . ''S. elliptica'' is placed within the section ''Rubella'' P. Ashton (red meranti timber) but the wood of this species is usually traded as a red balau. In terms of wood anatomy, this species resembles species of the section ''Shorea'' , which is in accordance with the trade classification. The timber of ''S. kunstleri'' and ''S. inaequilateralis'' Sym. is traded either as red balau or red meranti. However, these species belong in the section ''Brachypterae'' Heim, which otherwise includes red meranti timbers. The distincion between red balau and red meranti is not sharp. Several species may yield both types of timber (depending on the density). Their classification in either one of the groups, as presented here, is debatable. ''S. kunstleri'' is treated as red balau, ''S. inaequilateralis'' as red meranti, together with some other species producing both types of timber ( ''S. albida'' , ''S. balangeran'' ).

The wood of several species of ''Hopea'' , of ''Parashorea aptera'' v. Slooten and of ''Upuna borneensis'' Sym. is sometimes traded as balau as well.

''Shorea'' species are confined to the tropics with average annual rainfall exceeding 1600 mm and a dry season of less than 6 months. Most species occur below 1000 m altitude. They reach the largest number of species and individuals per species on deep, well-drained soils in the lowland. Comparatively few species are restricted to a single vegetation type or substratum, whereas some species are common to gregarious in a certain habitat but are also found scattered in others. A few species are confined to specific edaphic habitats such as heath (kerangas) forest (e.g. ''S. materialis'' ) or sandy soils (e.g. ''S. falcifera'' , ''S. geniculata'' ).

Trials on propagation of balau and red balau have been carried out occasionally. Like other ''Shorea'' species, the seeds lack dormancy. Experiments in Indonesia showed a maximum germination rate of 70% within 6 days for ''S. laevis'' seeds after 4 days of storage; the fruit wings were removed and the seeds were sown in shaded nursery beds. However, the survival rate of seedlings is usually low. A maximum of 40% was observed in seedlings of ''S. astylosa'' in the Philippines, transplanted when about 20 cm tall. Seedlings of ''S.'' ''guiso'' raised in the nursery had a survival rate of only 20%. Attempts to propagate ''S. seminis'' from cuttings in Malaysia failed. ''S. guiso'' and ''S. seminis'' are commercially propagated in East Kalimantan.

'''== Silviculture and management''' == Under selective cutting systems, natural regeneration may be good, at least locally, but is often unevenly distributed (e.g. ''S. laevis'' ). If natural regeneration is inadequate, enrichment planting may be practised using seedlings 20-25 cm high from the forest or nursery. Since most species are slow growers, cutting cycles should be adequately long.

Seeds and seedlings are regularly attacked by insects. The weevil ''Nanophyes shoreae'' has been reported to attack and destroy large numbers (more than 90%) of seeds of ''S. laevis'' in East Kalimantan. Feeding of insects on ''S. maxwelliana'' seedlings of 10-40 cm tall was found to be less severe than in some red meranti-producing species ( ''S. leprosula'' Miq., ''S. acuminata'' Dyer), probably because of a higher content of essential oils in the former.

Balau and red balau as timber groups include many species. Some of them occur widespread and gregariously (e.g. ''S. guiso, S. laevis, S. maxwelliana'' ), but others are much less common or occur only locally (e.g. ''S. collina, S. elliptica, S. falciferoides, S. geniculata, S. inappendiculata, S. lumutensis, S. malibato'' ). Since identification at species level is usually not made before logging, the latter group of species may be liable to genetic erosion or even extinction. Some species are threatened in specific areas and should be protected there, e.g. ''S. materialis'' and ''S. scrobiculata'' in Peninsular Malaysia.