L a réputation dubois de teck s’est

construite à traversl’utilisation des boisdes forêts naturelles.Cette ressource, large-ment surexploitée de-puis le XIXe siècle, aété partiellement re-constituée grâce à desplantations réaliséesen Asie, en Afrique eten Amérique. La majo-rité de ces plantationsest aujourd’hui en pro-duction.

La sylviculture desplantations de teck re-pose sur une séried ’ é c l a i rcies succes-sives dans les jeunespeuplements. De fait,

les bois de plantationd i ff è rent de ceux deforêt naturelle parl’âge, les dimensions,les qualités technolo-giques, la couleur. . .Cela conditionne lestypes d’utilisation et lavalorisation de ces boisjeunes et de petites di-mensions. A term e ,c’est la rentabilité finan-c i è re des plantations deteck qui est concern é epar ces questions. Dansle même temps, il fautnoter que le marché dubois de teck s’est diver-sifié et adapté à la re s-s o u rce. Tous ces sujetssont abordés dans cedossier sur le bois det e c k .

5BOIS ET FORÊTS DES TROPIQUES, 2000, N° 263 (1)

d o s s i e r

Troisième part i eLe bois de teck

Utilisation du bois dans la fabrication de produits haut deg a m m e .Use of wood in the manufacture of upmarket objects.

6 BOIS ET FORÊTS DES TROPIQUES, 2000, N° 263 (1)

LE TECK EN FRANCE

In the tropics, teak (Tectona grandisL.f.) is clearly the most preferred tim-ber species for the production ofhigh quality sawn wood and veneerfrom fast-growing plantation hard-wood (photo 1). “Among timbersteak holds the place which the dia -mond maintains among preciousstones and gold among metals” (SirDIETRIC BRANDIS). In addition to en-demic countries, e.g. India, Myan-mar, Thailand and Laos, teak hasbeen introduced in exotic forestrycontexts in almost all tropical partsof the world, including the followingcountries: • Asia Pacific RegionB a n g l a d e s h , N e p a l , Pakistan, Sri Lanka, Cambodia, Indonesia,Malaysia, Vietnam, Philippines, Taiwan, Japan, Australia, Fiji, etc.• East and West African RegionTanzania, Sudan, Somalia, Zim-

Timber qualityof teak

from managedt r o p i ca l

p l a n t a t i o n swith specialre f e rence to

Indian plantations

The author compares thetechnological properties

of plantation-grownteakwood with referenceto a study undertaken at

Nilambur (India).Contrary to general

opinion, it was found thatthe quality of wood

derived from dominantfast-growing trees was not

inferior to that fromslower-growing trees. Tips

for intensive teak timbermanagement are also put

forward.

K. Mahabala BHAT

Photo 1. Intensively managed shortrotation teak plantation.Plantation de teck à rotation courte etexploitation intensive.

TABLE I

STATUS OF TEAK PLANTATIONS IN IMPORTANT TEAK PRODUCINGC O U N T R I E S

Extent of Initial Rotation MAI Number of CPTCountry plantations spacing (yr) (m3/ha/yr) selected in

(thousands ha) (m) tree breeding

Bangladesh 1.8 × 1.8 40 7.4 319Brazil 25 10-13India > 1 500 1.8 × 1.8 50-80 5-9 714

2 × 22.5 × 2.53.6 × 2.7/3.6

Indonesia 1 080.867 3 × 3 60-80 5-6 122Côte d’Ivoire 21 5-7 to 10-16Malaysia 2.45 2.5 × 2.5 35-40

to4 × 4.5

Nigeria > 70 2.44 × 2.44 to 272.96 × 2.96

Sri Lanka 70.814 3 × 3 40 7Tanzania 5 12-19Thailand 170 2 × 4 40-60 13.52 260

4 × 4CPT : candidate plus tree.MAI : mean annual increment.Source: BHAT, INDIRA (1997a).

babwe, Uganda, Kenya, Malawi,Senegal, Guinea, Côte d’Ivoire,Ghana, and Nigeria.• Central and South American Re-gionBelize, Costa Rica, El Salvador,Cuba, Panama, Honduras, West In-dies, Jamaica, Nicaragua, etc. Per-country statistics on teak planta-tion area are scarce. The availabledata are given in table I.

TIMBER QUALITYCRITERIA

Teak timber quality, which could beaffected by high input management,depends partly on tree form andpartly on basic wood structure andstrength properties. The major struc-tural factors that should receive plan-tation managers’ attention are: treeheight and diameter, bole shape(taper, buttressing, fluting, etc.),knot size and frequency, grainangle (degree and pattern of spiral-ity), tension wood and juvenilewood proportions, heartwood-sap-wood proportions and characteris-tics (colour and extractives), grainand texture, i.e. the proportion andarrangement of tissues, includingearlywood and latewood propor-tions (growth ring width) and cell di-mensions.Comparative suitability indiceswere drawn up in India with the aimof developing a system for end-useclassification of a large number oftropical hardwoods, using teak asthe reference species (RA J P U T, GULATI, 1983). With the renownednatural durability and decorativevalues of heartwood, teak is emi-nently suitable for multiple end uses,including construction, furniture andcabinets, railway sleepers, decora-tive veneer, joinery, ship and vehi-cle body building, mining, reconsti-

tuted products, etc. Indeed, teak issuitable for a wide range of enduses.

HEARTWOOD PROPORTION IN FAST- AND SLOW-GROWN

TREES

In plantation-grown timber, endusers seek a maximum volume ofheartwood with a minimum amountof non-durable sapwood. FE R G U-S O N (1934) observed that for thesame stem diameter there was ahigher proportion of sapwood intrees with faster growth rates due toimproved site quality. According toBH A T (1998), trees selected forfaster growth (“candidate plustrees”) did not show marked heart-

wood percentage differences in ma-ture trees at ages 55 and 65 y e a r s( f i g u r e 1). In contrast, in youngtrees at age 13 years, faster growthwas correlated with higher heart-wood percentage. The effects ofgrowth rate on the timber heart-wood-sapwood ratio seemed to de-cline with age, resulting in negligi-ble differences between fast– a n dslow-grown trees. Figure 1 clearlyshows that longer rotation is moreimportant than slower tree growthwith respect to producing a higherpercentage of heartwood. Never-theless, lower heartwood contentdue to young age would be accept-able for improving pulp quality andpreservative treatment of thinnedm a t e r i a l .

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TEAK IN FRANCE

Figure 1. Comparison of mean heartwood percentages (at breast height) of fast-,medium-and slow-grown teak from the same plantations at different ages withinthe same geographic location in India (Nilambur).Comparaison des pourcentages moyens de bois de cœur, à hauteur d’homme,pour des tecks à croissance rapide, moyenne et lente issus des mêmes plantations,à différents âges dans un même lieu géographique de l’Inde (Nilambur).

TIMBER WEIGHT AND STRENGTH

The general assumption amongteakwood users is that fast-grownteak produces only light, weak andspongy wood. On the contrary, newdata available from an ongoing re-search project (figures 2-4) revealedthat trees selected for faster growthin forest plantations of different ages(21, 55 and 65 years) mostly dis-play non-significant differences inwood specific gravity and mechani-cal properties, including fibre stressat elastic limit, Young’s modulus,modulus of rupture and maximumcrushing stress (parallel to grain).These results support the findingsthat wood specific gravity (at 12%moisture content) and mechanicalproperties are independent ofgrowth rate and fast-grown trees ofring-porous species have higherwood specific gravity and strength.Furthermore, figures 2 to 4 clearlyindicate that wood specific gravityand strength properties of youngtrees (e.g.13- and 21-years-old) arenot necessarily inferior to older treesat ages 55 and 65 years. This offersscope for reducing the rotation ageof fast-grown wood without affect-ing timber strength. Test results onteak samples obtained from differ-ent countries such as Bangladesh,India and Myanmar indicate that thestrongest wood is produced fromtrees with modest radial growth of 4-5 mm annually. Timber samplesshould therefore be collected andtested from plantations where treeswere forced to grow very rapidlywith high silvicultural inputs such ascontinuous irrigation and fertilisa-tion before assessing growth-prop-erty relationships. Considerable evi-dence is available from differentparts of the world which shows thatplantation-grown teak is not inferiorto naturally-grown timber in terms ofstrength properties, but in some lo-calities naturally-grown teak showssuperiority or vice versa. Discrepan-

cies in research findings could main-ly be attributed to different tree re-sponses during wood formation todifferent growth-enhancing factorssuch as spacing/thinning, site con-ditions including moisture and nutri-ent status, as well as heredity andgenetic interactions with the envi-ronments. Furthermore, very heavyand moderate thinning treatmentsdid not alter the strength propertiesof teak in India and Myanmar(KADAMBI, 1972).Growth enhancement due to the con-trol of insect defoliation in juveniletrees did not alter cell wall percent-age and specific gravity of woodformed at ages 6, 7, and 8 y e a r s .Similarly, when trees from the sameplantation were analysed, fastergrowth in the juvenile wood (within 8rings from pith) did not alter the spe-cific gravity and cell wall percent-ages, while there was a significantpositive correlation between the ringwidth and cell wall percentage inmature wood. This is because the rel-ative proportions of latewood andfibre wall substance are more pro-nounced in wider rings of maturewood (60-65 rings from pith) than injuvenile wood (BH A T, 1998). How-ever, without regard to juvenile andmature wood zones, RA O et al.(1966) concluded that there was nosignificant relationship between ringwidth and tissue proportions.The effects of growth rate in juvenileand mature woods are clearly of different magnitudes, particularlyheartwood percentage and strength.The general belief that fast-growingring-porous hardwoods producedenser and stronger wood is thus notapplicable to very young juvenileteak trees, i.e. 5-8 years or less.

INTENSIVE MANAGEMENT

In India, 2 × 2 m initial spacing fol-lowed by two early mechanical thin-

nings and then silvicultural thinningsis the most common strategy formanaging forest plantations. How-ever, wider spacing, such as 2.5 ×2.5 m, 3 × 2.5 m or 4 × 5 m, is nowmore common in commercial teakplantations set up by private opera-tors, e.g. in Indonesia, Malaysiaand Thailand. Previously, the 2.5 ×2.5 m spacing pattern was also rec-ommended in India since pruningwas found to be useful for achievingthe desired grade and for recoveryof sawn wood with fewer defects. Inhigh forest zones of Nigeria, the rec-ommended spacing is between2.44 × 2.44 m and 2.9 × 2.9 m al-though percentage survival, dbhand specific gravity were found toincrease with spacing up to 3.96 ×3.96 m. Data available on the ef-fects of spacing/thinning regimeson wood quality are insufficient fordesigning an efficient managementstrategy, although very heavy andmoderate thinning treatments werefound to not alter the strength prop-erties of timbers in India and Myan-mar (KADAMBI, 1972).

FERTILIZER TREATMENT

In India, fertilizer (mixture of nitro-gen, phosphorus and potassium)treatment of 5-year-old trees prompt-ed a greater than twofold increasein ring width and a 15% increase inwood specific gravity, while vesseldiameter and fibre wall thicknessdid not show significant changes(table II). The increase in ring widthwas accompanied by a slight reduc-tion in vessel percentage and aminor increase in fibre percentage,resulting in a slight increase in spe-cific gravity. Similarly, apart from a20% lower modulus of elasticity andslightly higher shrinkage rates dueto juvenility, the similar bending andcompression (parallel to grain)strength levels of treated 5-year-oldtrees relative to mature wood indi-

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cates that timber produced in fertil-ized stands is not necessarily weaker. This suggests that there is no causefor concern with regard to the wood

quality of fertilized stands, at leastfor juvenile wood production, butfurther data are required to be ablet o p r e s c r i b e s u i t a b l e f e r t i l i z e rdosages.

IRRIGATION EFFECTS

As compared to standard teak,while some studies revealed highvalues for bending and compression

TABLE III

MEAN VALUES OF SELECTED MECHANICAL PROPERTIES (AIR-DRIED CONDITIONS) FOR IRRIGATED TEAK INTHREE LOCATIONS (INDIA) COMPARED WITH MEAN CONTROL VALUES FOR STANDARD INDIAN TEAK

Property Control Locations of irrigated plantations in India

Tamilnadu Karnataka Maharashtra

Specific gravity 0.645 0.591 0.564 0.479Static bending (MORN/mm2) 86.5 121.2 129.4 60Stiffness (MOE N/mm2) 10 745 17 215 17 147 6 921Max. compressive stress parallel to grain (N/mm2) 47.7 57.9 51.2 29

Source: BHAT (1998).

TABLE IIWOOD PROPERTIES OF AN INTENSIVELY MANAGED 5-YEAR-OLD PLANTATION COMPARED WITH CONTROL

(based on sampling of 10 dominant trees each)

Property Control Fertilized trees Test of significance

Mean SD Mean SD

Diameter at breast height (cm) 7.8 0.9 11.0 0.6 **Basic specific gravity 0.444 0.035 0.522 0.03 **Ring width (mm) 2.8 1.1 7.7 3.2 **Vessel element length (mm) 0.270 0.06 0.300 0.01 *Vessel diameter (µm) 116 9 118 16 nsFibre percentage 56.4 3.2 63.5 1.6 *Vessel percentage 18.5 3.9 12.5 1.8 *Parenchyma percentage 17.8 2.2 24.0 1.7 nsFibre length (mm) 0.80 0.02 0.895 0.04 *Fibre wall thickness(µm) 4.3 0.6 4.6 0.5 nsMicrofibrillar angle(˚) 19 1 21 1 nsRadial shrinkage (%) 4.1 2.0Tangential shrinkage (%) 5.9 1.2Vol. shrinkage (%) 10.0 2.9FS-EL (N/mm2) 86 10MOR (N/mm2) 111 12MOE (N/mm2) 8 141 2 612MCS (N/mm2) 45.9 5.5

strength of irrigated plantation tim-ber from two different states in India,another study reported lower valuesin trees irrigated with sewage waterin Maharashtra (table III). More re-search data are required to be ableto draw up an irrigation schedule forfaster growth of plantation teaktrees.

JUVENILE WOODIn commercial teak plantations,trees are grown very rapidly to re-duce rotations to 20-30 years fromthe traditional practice of 50-80 years (table I). This results in ahigher proportion of juvenile woodin harvested timber. Problems com-monly associated with juvenilewood are excessive longitudinalshrinkage, warp and reducedstrength with lower specific gravity.New evidence suggests that differ-ences between juvenile and maturewood are not sufficient to affectmeeting many end-users’ require-ments. Compared to mature wood,juvenile teakwood is characterisedby wide rings, short fibres, small di-ameter vessels, low vessel percent-age, high cell wall percentage,wide microfibrillar angle and rela-tively low or almost similar mechan-ical properties (photo 2). With re-gard to timber strength, there isscope for reduction of rotation peri -ods to about 20 years as recent re-sults indicate that the mechanicalmaturity of teakwood occurs at thisage and further improvement ofstrength properties with age is prac-tically negligible (figures 2-5). Theonly anticipated problems are re-ductions in natural resistance (due tolower heartwood content and ex-tractives) and lower recovery ofsawn wood and veneer, owing togrowth stresses and smaller log di-ameter as well as a higher propor-tion of knots. These results indicatethat a better understanding of juve-

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LE TECK EN FRANCE

Photo 2. Microphotography of juvenile wood (left) and mature wood with barktissue (right).Microphotographie de bois juvénile (à gauche) et de bois mature (à droite) mon -trant le tissu cortical.

Figure 2. Comparison of air-dried wood density (kg/m3) of fast-, medium- andslow-grown teak within the same geographic location (Nilambur) at differenta g e s .Comparaison de la densité du bois séché à l’air (kg/m3) de tecks à croissance ra -pide, moyenne et lente, à différents âges, issus du même lieu géographique (Ni -l a m b u r ) .

nile wood structure and properties isneeded for efficient utilisation of ju-venile teakwood resources in futuretropical plantations.

HIGH SAPWOODVOLUME IN SHORTROTATION TIMBER

Results showing a consistent in-crease in heartwood volume withtree age suggest that sapwood yieldper tree will be higher from thinningsand relatively small timber harvest-ed from short rotation plantations.The mean sapwood proportion atbreast height of 21-year-old trees is40%, in contrast to 16% and 15% in55- and 65-year-old trees, respec-

tively (figure 1). This means that thesapwood yield from existing planta-tions is considerable although thiswood is not necessarily inferior withrespect to all strength properties.The main concern is reduced naturaldurability of sapwood for structur-al/solid wood uses unless the mate-rial is adequately treated with envi-ronment-friendly preservatives. Withhigher penetrability, sapwood iseasier to treat with preservativesthan refractory heartwood. The utili-sation potential of short rotationteakwood is also evident from thefollowing observations:• Teak can attain optimum timberstrength properties in 21-year-oldforest plantations, as recorded inIndia.• The mean annual increment (MAI)recorded for shorter rotations of

20-30 years is almost twofold (10-20 m3/ha/year) that of tradi-tional 60-year-rotations.

• Faster growth is correlated withthe higher heartwood percentageof juvenile trees. Plantation man-agers therefore can aim at produc-ing larger diameter logs withgreater heartwood yield (largercylinder) per tree by acceleratingtree growth of short rotation planta-tions. This means that growers canget better timber prices for eachfast-grown tree of larger size if itcan meet the property/processingrequirements of high-value productssuch as veneer and sawn wood ofdesired dimensions.

FIGURE (COLOUR,GRAIN, TEXTURE) OFTEAKWOOD FROMMANAGED STANDS

Wood colour differences betweenmanaged stand trees and controltrees are small compared to differ-ences due to geographic location( p h o t o 3). For instance, teak grownin Nilambur (India) is golden brownor yellow, while that from Konni is adarker golden brown colour. Thefigure shows that heartwood of 5-year-old teak from a managedstand is almost similar in colour.However, grain and texture is slight-ly different since rapidly grown ju-venile teakwood loses its typicalring porosity, and vessels becomemore uniform in size (photo 4). Fast-grown juvenile wood is thus likely tobe finer and more evenly texturedthan traditional teakwood, whichwill have some influence on the mar-ket value of the timber, although theprice will not necessarily be muchlower.

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TEAK IN FRANCE

Figure 3. Comparison of maximum bending strength (N/mm2) of fast- and slow-grown teak within the same geographic location (Nilambur) at different ages.Comparaison des contraintes de rupture en flexion (N/mm2) de tecks à croissan -ce rapide, moyenne et lente, issus du même lieu géographique (Nilambur) et àdifférents âges.

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LE TECK EN FRANCE

GENETIC SELECTIONGEOGRAPHIC/PROVENANCE/

CLONAL EFFECTS

The quality of Myanmar teak is con-sidered to be superior because ofthe straighter cylindrical stems–al-though trees from northern parts ofthe country are often crooked andcross-grained (TINT, KYU PE, 1995).Teak also displays wide variationsunder different growing conditionsand regions in India. Malabar teak(Nilambur, Kerala), generally hav-ing good growth and log dimen-sions with desirable figure, is com-monly used for ship-building.Slow-growing trees from drier local-ities, which resist forest fire and tendto develop twisted/wavy grain, areknown to yield heavier, strongerclose-grained wood with a beautifulfigure. In a preliminary study, it was

found that the percentage of logswith flutes and knots was greater ingenerally quicker growing locations(Nilambur) than in slow-growingareas (Konni) of India (BHAT, 1998).

Figure 4. Comparison of maximum crushing strength parallel to grain (N/mm2) offast- and slow-grown teak within the same geographic location (Nilambur) at dif-ferent ages.Comparaison de la contrainte de rupture en compression parallèle (N/mm2) detecks à croissance rapide, moyenne et lente, issus du même lieu géographique(Nilambur) et à différents âges.

Photo 3. Plain sawn wood samplefrom intensively managed 5-year-old juvenile wood (left) comparedwith 8-year-old wood (control), dis-playing colour, grain, and texture ona tangential surface.Echantillon de bois scié normale -ment provenant de bois juvénile( 5 ans) d’exploitation intensive (àgauche), comparé à du bois de 8 a n s(contrôle) et montrant la couleur, legrain et la texture sur une surface tan -g e n t i e l l e .

Photo 4. Transverse section showing a resumption of ring porosity in fast grownteak after 5 years of growth.Coupe transversale montrant la zone semi-poreuse dans du teck à croissance ra -pide après 5 ans de croissance.

Timber produced in plantations fromTrinidad was not inferior in terms ofmechanical properties to samplesfrom Myanmar (SMEATHERS, 1951).According to BRYCE (1966), the me-chanical properties of 51-year-oldTanzanian-grown teak were 15% in-ferior to teakwood from Myanmarand Trinidad. Teak samples fromWest Africa were found to be har-der and heavier than those fromAsian regions (SALLENAVE, 1958).Considerable evidence is availablefrom different parts of the worldwhich show that plantation-grownteak is not inferior to naturally growntimber in terms of strength proper-ties, although in some localities nat-urally grown teak is superior or viceversa (BHAT, 1998).

SELECTION OF CLONES/PROVENANCES FOR WOOD

SPECIFIC GRAVITY

Recent tests conducted in the KeralaForest Research Institute showed thatthere was no significant differencebetween clones; and the phenotypiccoefficient of variation was as lowas 8% (BHAT, INDIRA, 1997). The es-timated genotypic coefficient of vari-ation was 0-3%, which is almostnegligible. The relative indication ofgenetic control over wood specificgravity is seen from low values ofbroad-sense heritability.The genetic gain was found to be1.7% of the mean on an individualtree basis and 3.3% of the mean ona clonal basis. Although heritabilityon a clone-mean basis was higherthan on an individual tree basis, thegenetic gain was only 3.3 %. Thiswas due to the low coefficient ofvariance shown by the clone. Ifgood clones are identified and envi-ronmental conditions are suitable,wood specific gravity can be im-proved.Among the six provenances, thewood specific gravity of 60-year-oldtrees was not significantly correlated

with dbh, although the Nilamburprovenance had the highest specificgravity and tree diameter (table IV).The North Burma (Myanmar) prove-nance displayed poor growth withrelatively high wood specific gravi-ty. Selection of provenances and in-dividual trees for faster growthwould not likely adversely affect thestrength or solid wood uses.PURKAYASTHA and SATYAMURTHI(1975) also reported that seed ori-gin contributed to only 1.5% of thevariation, while the locality factorcontributed to 31.4% of the varia-tion–but the analysis was basedsolely on limited data from twoprovenances. These results implythat provenance selection will not bevery effective for genetic improve-ment of specific gravity, but the with-in provenance variation (tree-to-treevariation) should be exploited. Forinstance, two dominant trees of thesame age and grown in the sameplantation showed different patternsof pith-to-bark variations in specificgravity, probably due to genetic dif-ferences (BHAT et al., 1989). It is im-portant to take advantage of thissource of variation in selecting andproducing structural timber of de-sired weight and strength with moreuniform specific gravity distributionfrom pith to bark regions. However,selection of specific gravity alone in

genetic improvement of timber qual-ity will be misleading due to the in-consistent relations with mechanicalproperties (BHAT, INDIRA, 1997b).While much literature is availablefor some temperate tree species,e.g. poplar, radiata pine and loblol-ly pine, knowledge is limited on ge-ographic/seed source/provenancevariations in specific gravity andstrength of teak (PURKAYASTHA et al.,1975). Nevertheless, according toBRYCE (1966), the mechanical prop-erties of 51-year-old Tanzanian-grown teak were 15% inferior tothose of Myanmar and Trinidad.Once the best provenances areidentified for certain regions/coun-tries, individual trees with superiorwood quality traits could be selectedfor future planting stock. It has beenshown that wood specific gravityvariation patterns with age are notthe same in fast-growing trees. Twodominant teak trees of the same ageand grown in the same plantationshowed different radial variationpatterns, probably due to geneticdifferences (BHAT et al., 1989). Thissource of specific gravity variationshould be tapped for selecting andproducing timber of desired weightwith more uniform specific gravitydistribution from pith to bark regionsfor structural purposes since specific

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TEAK IN FRANCE

TABLE IV

MEAN BASIC SPECIFIC GRAVITY VALUES OF DOMINANT TREES FROM SIX PROVENANCE TRIALS OF 60-YEAR-OLD TEAK (n = 5 )

Provenance dbh (cm) Specific gravitymean cv (%) mean cv (%)

Nilambur 40.1 21.8 0.539 11.9Anamalais 39.0 18.6 0.528 10.9Travancore 36.3 15.7 0.486 13.5South Bombay 37.6 14.7 0.488 6.5South Burma (Myanmar) 39.9 21.2 0.524 7.9North Burma (Myanmar) 31.5 10.9 0.538 9.1

cv: coefficient of variation.

14 BOIS ET FORÊTS DES TROPIQUES, 2000, N°263 (1)

LE TECK EN FRANCE

gravity has proven to be a heritableproperty in many species.

PROCESSING SMALLDIMENSIONAL

TIMBERSawing trials undertaken to evaluatesmall timber yields for furniture stockand strips gave satisfactory results inplantation grown teak from Côted’Ivoire (DURAND, 1983). The twomajor factors that influenced sawnwood grade and recovery were un-sound hollow knots and deep flutesin the logs. SANGKUL (1995) report-ed 51% sawn wood recovery from20-year-old trees, with a log diame-ter range of 9-20.5 cm, by throughand through sawing. In a prelimi-nary study, it was found that the per-centage of logs with flutes and knotswas greater in a generally quickergrowing location (Nilambur) than ina slow-growing area (Konni) inIndia. However, no relevant dataare available for timber grown withintensive silvicultural practices, in-cluding pruning.

FURTHER RESEARCHBecause of the complexity of siteconditions as well as genetic and en-vironmental interactions, the resultsof a short-term study from one coun-try are not sufficient to develop aspecific strategy for high input man-agement. Nevertheless, they offerscope for using intensive techniquessuch as genetic selection and fertil-izer treatment to obtain higher

yields without reducing timbervalue. One possible option wouldbe to grow teak in the most suitablesites in order to tap the maximum bi-ological potential of trees and as-sess the economic returns of highinput management.Interventions with appropriate pro-cessing technologies are needed forconversion (sawmilling) of small di-mensional timber, solar drying andtreatment with environment-friendlypreservatives–in this way, qualityproducts can be manufactured thatmeet market standards. They also in-clude processing of early thinningsand small dimensional materials for

t h e m a n u f a c t u r i n g v a l u e - a d d e dproducts such as finger-jointed struc-tures (for buildings), decorative ve-neer, furniture components, handi-crafts/toys/souvenirs, etc. Revisionof grading regulations and drawingup industrial codes of conduct arenecessary for internal quality controland to ensure the quality of productsderived from sustainable plantationmanagement.

c K. Mahabala BHATKerala Forest Research Institute

Peechi 680 653TRICHUR DIST. KERALA

India

TIPS FOR TEAK TIMBER MANAGEMENTPlantation managers can aim at producing larger diameter logs withgreater heartwood yield (larger cylinder) per tree by accelerating treegrowth in short rotation plantations of about 20 years.Teak can produce timber of optimum strength in relatively short rota-tions of about 20 years.Fast-growing provenances/clones can be selected for teak manage-ment without reducing timber weight/specific gravity.Selection of individual trees within a specified provenance can offergreater potential than selection of provenances in breeding pro-grammes for the improvement of teakwood specific gravity.Wood specific gravity is not always the best single indicator of overallgenetic improvement of timber quality.Faster growth in relatively young forest plantations with judicious fertili-zer application/genetic inputs can turn out to be advantageous in termsof heartwood volume per tree and timber strength.More research is required on timber durability, preservative treatmentof sapwood, strength properties, as well as quality standards/gradingrules for fast-grown teak under high input management conditions.

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BANIK R. L., 1993.Teak in Bangladesh. In: Teak in Asia. HenryWood (ed.). FAO, Bangkok, p. 1-10.

BHAT K. M., 1998.Properties of fast-grown teak wood: impacton end-user’s requirements. J. Trop. For.Prod. 4(1): 1-10.

BHAT K. M., BHAT K. V.,DHAMODARAN T. K., 1989.Radial patterns of specific gravity variationsin eleven tropical hardwoods.Holzforschung 43(1): 45-48.

BHAT K. M., INDIRA E. P., 1997a.Teak timber production in intensively man-aged plantations of the tropics. In: The XIthWorld Forestry Congress, 12-22 October1997, Antalya, Turkey.

BHAT K. M., INDIRA E. P., 1997b.Specific gravity as selection criterion of ge-netic improvement of teak wood quality: treebreeder’s perspective. In: Timber manage-ment toward wood quality and end-productvalue. S. Y. Zhang, R. Grosselin &G. Chauret (eds). Proceedings CTIA-IUFROWorkshop, Quebec, Canada, p. 91-96.

BRYCE J. M., 1966.Mechanical properties of Tanzania-grown

teak. Technical note, Utilisation, School ofForestry Division, Moshi n˚ 34.

DURAND P. Y., 1983.Wood technology research in Ivory Coast:towards a rational utilisation of lesser-knownforest species and technological control ofplantation grown timber in quality and quan-tity. IUFRO Division 5 Conference, Madison,USA.

FERGUSON Jr. I. H. A., 1934.Thickness of heartwood and sapwood of teak (Tectona grandis L.f). Tectona 27:313-327.

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R E F E R E N C E S B I B L I O G R A P H I Q U E S

16 BOIS ET FORÊTS DES TROPIQUES, 2000, N°263 (1)

LE TECK EN FRANCE

R É S U M ÉQUALITÉ DES BOIS DE TECK ISSUS DE PLANTATIONS TROPICALES AMÉNAGÉES

Avec une mention particulière aux plantations indiennesDepuis le développement récent des plantations commerciales dans la plupart des pays tropicaux, la qualité des bois de teck à crois-sance rapide suscite un intérêt grandissant. Du fait du peu de données disponibles, des critères de la qualité de ces bois ont été choisisafin de faciliter le contrôle de leurs propriétés. Contrairement à l’opinion générale, les arbres dominants (phénotypiquement supérieurs)à croissance rapide comportent une proportion plus élevée de bois de cœur pendant la phase juvénile de croissance, jusqu’à la21e année, les différences ne sont plus significatives pour des arbres adultes âgés de 55 et de 65 ans. La rapidité de la croissance aeu très peu d’effet sur la résistance des bois de teck issus de plantations de 13, 21, 55 et 65 ans. Le teck a l’avantage de produire dubois de très grande résistance dans des conditions de rotation relativement courtes de 21 ans, dans les plantations favorables à sa crois-sance. Les données sur des plantations de tecks juvéniles sous une exploitation intensive montrent que: (a) les provenances à croissancerapide peuvent être sélectionnées pour l’exploitation du teck sans une réduction de la densité du bois ; (b) la sélection d’arbres indivi-duels au sein d’une même provenance offre de meilleures possibilités d’améliorer la densité du bois que la sélection de provenances re-levant de programmes d’amélioration ; (c) la densité du bois n’est pas toujours, par elle-même, le meilleur indicateur d’une améliorationgénétique globale de la qualité du bois ; (d) une croissance plus rapide dans des plantations forestières relativement jeunes, favoriséepar l’utilisation judicieuse de matériel génétique et d’intrants, peut être avantageuse sur le plan du volume de bois de cœur produit pararbre et de la résistance du bois ; (e) il est probable que le bois juvénile issu de plantations d’exploitation intensive différera du bois deteck classique par le grain et la texture, ce qui modifiera la valeur marchande du bois ; (f) la recherche sur la durabilité du bois, le trai-tement préventif de l’aubier, les propriétés de résistance et les normes de qualité ainsi que les règles de classement du teck à croissan-ce rapide doit être approfondie dans des conditions d’exploitation intensive.Mots-clés : Tectona grandis, plantation forestière, arbre plus, opération forestière, propriétés technologiques.

A B S T R A C T

TIMBER QUALITY OF TEAK FROM MANAGED TROPICAL PLANTATIONSWith special reference to indian plantations

With the recent development of commercial plantations throughout most of the tropics, there has been renewed interest in fast-grown teaktimber quality. Some selected wood properties of fast-grown teak are appraised on the basis of current limited data to determine the qua-lity of timber from intensively managed plantations. Contrary to common opinion, fast-growing dominant (phenotypically superior) treeswere found to yield a higher percentage of heartwood per tree during the juvenile period (up to 21 years), whereas the differences werenot significant in the mature period (55 and 65 years). Faster growth had very little effect on the strength of timber from 13-, 21-, 55- and65-year-old plantations. Teak offers potential for producing timber of optimum strength with relatively short rotations of 21 years at suitableplantation sites. Data from intensively managed juvenile teak plantations indicate that: (a) fast-growing provenances/clones can be se-lected for teak management without reducing wood specific gravity. (b) Selection of individual trees within a specific provenance offersgreater potential than selection of provenances in breeding programmes for the purpose of improving wood specific gravity. (c) Woodspecific gravity is not always the best single indicator of overall genetic improvement of timber quality. (d) Faster growth in relatively youngforest plantations with judicious fertilizer application/genetic inputs can be advantageous in terms of heartwood volume per tree and tim-ber strength. (e) Juvenile wood from intensively managed plantations will likely differ from traditional teakwood with respect to grain andtexture, thus influencing the market value of the timber. (f) More research is required on timber durability, preservative treatment of sap-wood, strength properties, and quality standards/grading rules of fast-grown teak under high input management conditions.Key words: Tectona grandis, forest plantation, dominant tree, forestry operation, technological properties.

R E S U M E N

CALIDAD DE LA MADERA DE TECA DE PLANTACIONES TROPICALES MANEJADASCon especial referencia a las plantaciones indias

El reciente desarrollo de las plantaciones comerciales en la mayoría de los países tropicales ha provocado un creciente interés por la cali-dad de la madera de teca de crecimiento rápido. Algunas propiedades de la teca de crecimiento rápido se evalúan en función de los li-mitados datos actualmente disponibles para determinar la calidad de la madera de plantaciones de explotación intensiva. Se ha observa-do que, al contrario de lo que se pensaba, los árboles plus de crecimiento rápido (fenotípicamente superiores) producen un porcentaje másalto de duramen por árbol durante el periodo juvenil (hasta los 21 años), mientras que las diferencias eran insignificantes en árboles ma-duros (55 y 65 años). La rapidez de crecimiento apenas afecta a la resistencia de maderas de teca de plantaciones de 13, 21, 55 y6 5 años. Una de las cualidades de la teca es la producción de madera de muy alta resistencia en rotaciones relativamente cortas (21 a ñ o s )en plantaciones adecuadas para su crecimiento. Los datos procedentes de plantaciones de teca juvenil de explotación intensiva indicanq u e: (a) las procedencias/clones de crecimiento rápido pueden seleccionarse para la explotación de la teca sin reducir la densidad de lam a d e r a ; (b) la selección de árboles individuales dentro de la misma procedencia proporciona mejores posibilidades para mejorar la den-sidad de la madera que la selección de procedencias dependiente de los programas de mejora ; (c) la densidad de la madera no essiempre el mejor indicador de una mejora genética global en la calidad de la madera ; (d) un crecimiento más rápido en plantaciones fo-restales relativamente jóvenes, favorecido por el empleo razonable de fertilizantes e insumos genéticos puede ser ventajoso en cuanto alvolumen de duramen producido por árbol y a la resistencia de la madera ; (e) es posible que la madera juvenil de plantaciones de explo-tación intensiva difiera de la madera clásica de teca en su grano y su textura, lo que modificará el valor comercial de la misma ; (f) la in-vestigación sobre la durabilidad de la madera, tratamiento preventivo de la albura, propiedades de resistencia y normas de calidad/ re-glas de clasificación de la teca de crecimiento rápido debe intensificarse en condiciones de explotación de alta producción.Palabras clave : Tectona grandis, plantación forestal, árbol plus, operación forestal, propiedades tecnológicas.