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FAO Timber plantationsplantations FORESTRY in the humidhumid tropicstropics PAPER ofof AfricaAfrica 98

by B. Dupuy Research EngineerEngineer,, CTFTCTFT,, CoteCôte d'Ivoired'ivoire and G. Mille ReResearchsearch EngineerEngineer,, CTFT, FranceFrance

Food and Organization of thethe United Nations

CENTRE TECHNIQUE FORESTIERFORESTIER TROPICAL DépartementDepartement forestier du CIRADCIRAD 45 bis, avenueavenue dede lala Belle-GabrielleBelle-Gabrielle 94736 Nogent-sur-MarneNogent-sur-Marne CEDEXCEDEX FRANCE Rome, 19931993 TheThe designationsdesignations employed and the presentation of material in this publicationpublication do not implyimply thethe expressionexpression of anyany opinionopinion whatsoeverwhatsoever on thethe part of thethe FoodFood andand AgricultureAgriculture OrganizationOrganization of thethe UnitedUnited NationsNations concerningconcerning thethe legallegal statusstatus ofof anyany country,country, territory, citycity oror area or of itsits authorities,authorities, oror concerningconcerning thethe delimitationdelimitation of itsits frontiers or boundariesboundaries..

M-32 ISBN 92-5-103020-092-5-103020-0

All rights reserved.reserved. No part of thisthis publicationpublication maymay bebe reproduced,reproduced, storedstored inin aa retrieval system, or transmittedtransmitted inin anyany formform oror byby any means, electronic,electronic, mechani-mechani­ cal, photocopying or otherwise, without thethe prior permission ofof the ropyrightcopyright owner.owner. Applications forfor such permission,permiSSion, withwith aa statement of the purpose and extent of the reproduction,reproduction, shouldshould bebe addressed toto thethe Director, Publications Division,Division, Food and Agriculture Organization of the UnitedUnited Nations,Nations, VialeViale delledelle TermeTerme didi CarCan-calla walla,, 00100 Rome,Rome, Italy.Italy.

© FAOFAO 19931993 - iii

PREFACE

The clearing ofof tropicaltropical forestsforests continuescontinues atat aa fastfast pace.pace. Certain countries inin the humid tropicstropics havehave over thethe past few decades lost the greatergreater part of theirtheir forestforest cover.cover. In additionaddition to payingpaying attention to sustainable managementmanagement of thethe remainingremaining ,forests, it is essentialessential toto greatlygreatly increaseincrease efforts in reforestationreforestation inin mostmost tropicaltropical countriescountries inin orderorder toto relieverelieve pressure onon thesethese forestsforests andand toto provideprovide rawraw materialsmaterials forfor present-daypresent-day use.use .

Through itsits considerableconsiderable experienceexperience inin manymany humidhumid tropicaltropical AfricanAfrican countries, thethe Centre TechniqueTechnique ForestierForestier TropicalTropical (now(now CIRAD-Forét)CIRAD -Foret) isis inin anan excellent position toto provide an overview of availableavailable knowledgeknowledge in commercialcommercial tree plantations inin thesethese countries.countries. SuchSuch anan overviewoverview isis presentedpresented inin the present paper.paper. The authors describe common techniquestechniques usedused andand lessonslessons learned from a great number ofo f fieldfield trialstrials carried out over the past in the closedclosed tropicaltropical forestforest zonezone ofof ,Africa, and provide informationinformation onon species selection and reforestationreforestation techniques.techniques.

The presentpresent document includes two main parts,parts, oneone onon enrichmentenrichment plantingplanting and oneone onon reforestationreforestation onon clearedcleared lands.lands. It recordsrecords thethe evolutionevolution inin forestry techniques inin thisthis regard,regard, and discusses a range ofof associatedassociated issues related tot o forestryf o restry inin thethe humidhumid tropics.tropics.

It isis clearclear thatthat the prOblemsproblems ofof deforestationdeforestation cannotcannot bebe solvedsolved throughthrough an isolated, t~chnicaltechnical approachapproach.. ManyMany related economic, social and institutional questionsquestions willwill needneed to be addressedaddressed in orderorder toto adequatelyadequately shoulder thet~e challengechallenge andand toto ensureensure thethe conservationconservation andand developmentdevelopment ofof thethe tropical forests.fores·ts·.

Recognizing thethe valuevalue andand importance of recording available information for the benefit of AfricaAfrica asas wellwell asas ecologicallyecologically similarsimilar zoneszones in otherother trtropicalopical regions,regions, FAOFAO agreedagreed toto publishpublish thethe present documentdocument preparedprepared byby thethe CTFTCTFT inin itsits ForestryFore stry PaperPaper series.series .

FAO sincerelysince rely thanksthanks thethe CentreCentre TechniqueTechnique ForestierForestier TropicalTropical forfor thethe cooperationc ooperation whichwhich ledled toto thethe preparationpreparation ofof thethe presentpresent document.document. Special thanks go to the twotwo main authors,authors, Messrs B. Dupuy and G. Mille, forfor theirtheir outstandingoutstanding work.work.

J.PJ.P.. Lanly F. Cailliez Director Director Forest Resources Division Centre Technique ForestierForestier TropicalTropical Forestry Department Forestry Department -- CIRADCIRAD FAO, Rome Nogent-sur-Marne, FranceFrance - iviv --

TABLE OF CONTENTSCONTENTS

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CHAPTER II -- HISTORICAL SURVEYSURVEY 1

1. DEFINITIONS 2

1.1 formationsformations 2 1.2 The concept ofof enrichmentenrichment 3

2. EVOLUTION OF METHODS: FROMFROM ENRICHMENT TO TOTAL REPLACEMENT 5

2.1 The line-planting method 5 2.2 The modified line-plantingline-planting method 6 2.3 The plot method 6 2.4 The undergrowth method 7 2.5 Total and gradual destruction of forests by devitalization 7 2.5.1 The regrowth method 7 2.5.2 The Martineau method 8 2.6 Total destruction of thethe forestforest beforebefore plantingplanting ·8 2.6.1 The Taungya method 8 2.6.2 The Limba method 9 2.6.3 Methods based on mechanized deforestationdeforestation 10

3. EXAMPLES OF APPLICATION OFOF THE METHODS DESCRIBED 10

3.1 CoteCôte dd'Ivoire1 Ivoire 10 3.2 NigeriaNigeria 11 3.3 12 33.4. 4 Congo 13 3.53 . 5 13 3.6 Zaire 14 3.73.7 OtherOther countries: , SierraSierra Leone,Leone , LiberiaLiberia 16

4. KNOWLEDGE ACQUIRED 16

4.14.1 TheThe light factor 16 44.2. 2 ChoiceChoice of species 17 44.3. 3 Results 17 - v -

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CHAPTER IIII -- RECENTRECENT TECHNIQUESTECHNIQUES AND ORIENTATIONS:ORIENTAT I ONS: REFORESTATION IN CLEARED AREAS

1. FORESTRY TECHNIQUESTECHNIQUES 19

1.1 Choice ofof sitessites 2211 11.1.1. 1.1 Appropriate sitessites forfor commercialcommercial reforestationreforestation 21 1.1.1.1.2 2 Criteria forfor choosingchoosing intensive-reforestationintensive-reforestation sitessites 22 1.2 Nurseries 26 1.2.1 produced fromfrom seedsseeds 26 1.2.2 Plants produced from cuttings 28 1.3 Preparation ofof thethe sitesite andand plantingp l anting 29 1.3.1 Preparation of the site 29 11.3.2. 3 . 2 Planting 31

2. THE TECHNICAL-FINANCIAL EVALUATIONEVALUATION 32

2.12. 1 The manual regrowth method 32 2.2 Association ofof reforestationreforestation withwith agricultureagriculture (Taungya)(Taungya) 32 2.32 . 3 The mechanized method 35 2.42 . 4 Technical evaluation 36 2.5 Financial assessmentassessment 39 2.6 Overall assessmentass·essment 40

3. PRINCIPLES FORFOR INTENSIVEINTENSIVE REFORESTATION 41

3.1 Constraints for intensive reforestationreforestation 41 3.2 Basic principles 42 33.3. 3 Limits on thethe introductionintroduction ofof plantationplantation speciesspecies 45 33.4.4 General silviculturals ilvicultural rulesrules 49 3.4.1 ClearingClearing 49 3.4.3.4.1.11.1 Mechanical method 50 33.4.1.2. 4.1.2 Chemical method 52 33.4.2. 4 . 2 Artificial pruning 54 33.4.3. 4 . 3 Thinning 55 3.4.4 Designation of finalfinal cropcrop treestrees 55 3.5 Dendrometric parametersparameters 57 3.5.1 Dendrometric characteristicscharacteristics ofof standsstands 57 3.5.2 Volume tables 60 3.5.3 Yield tablestables 62 3.5.3.13 . 5.3.1 Construction of provisional yield tables 63 3.5.3.23 . 5 . 3 . 2 Establishment of the various ratiosratios 67 3.5.3.33.5 . 3 . 3 Description ofof silviculturalsilvicultural practicespractices 67 3.5.3.43.5.3 . 4 Compilation of yieldyield tables 69 3.5.3.5 Validity limitationslimitations ofo f yieldyield tablestables 69 - vi --

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CHAPTER III -- SILVICULTURAL RULESRULES FORFOR THETHE PRINCIPALPRINCIPAL REFORESTATION SPECIESSPECIES 71

1. LONG-ROTATION SPECIESSPECIES 72

1.1 72 1.2 Okoume"Okoume 79 1.3 Niangon 82 1.4 Badi 85 1.5 86 1.6 Sipo 91 1.7 Ilomba 92 1.8 AzobeAzobé 93 1.9 MakoréMakore 96

2. MEDIUM-ROTATION SPECIESSPECIES 97

2.1 FramirdFramire 97 2.2 FrakéFrake 102 2.3 Samba 107 2.4 Cedrela odorataodorata 112

3. FAST-GROWING SPECIES FORFOR TIMBERTIMBER PROMOTIONPROMOTION 116

3.1 116 3.2 Gmelina arborea 120

4. SPECIES TO BE CONFIRMED 126

4.1 Padouk 126 4.2 alliodora 128 4.3 Cleistopholis glauca 131 4.4 Maesopsis eminiieminii 132 4.5 Funtumia elastica 134 4.6 Araucarias 136

5. PRODUCTIVITY CHARACTERISTICSCHARACTERISTICS 137

55.1. 1 The principalprincipal species 137 5.15.1.1. 1 Yield volume 137 5.1.2 Characteristics of thethe principal speciesspecies atat end of rotationrotation 140 5.2 Thinning products 142 - vii -

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5.3 Rotations periods 144 5.3.1 Ratio of exploitableexploitable diameterdiameter toto usableusable volumevolume 144 5.3.2 Ratio of exploitableexploitable diameterdiameter toto numbernumber of thinnings 145 5.3.3 Ratio of exploitableexploitable diameterdiameter toto averageaverage exploitable ageage 146 5.3.4 Exploitable diameterdiameter andand profitability 146 5.35.3.5. 5 Rotation recommendationsrecommendations 147

6. MIXED STANDS 148

6.1 Ways ofof associatingassociating twotwo speciesspecies inin mixedmixed standsstands 148 6.1.1 Creation of a two-storey stand 148 6.1.2 Creation of a single-storey stand 149 6.26 . 2 Comparative growthgrowth andand compatibilitycompatibility ofof mixedmixed speciesspecies 150 6.36 .3 Silvicultural constraintsconstraints onon thethe creationcreation ofof mixedmixed standsstands 155 6.4 Recommendations 158

7. PLANTATIONS OF FIFTY-EIGHTFIFTY-EIGHT LESSER-KNOWNLESSER-KNOWN SPECIESSPECIES NATIVE TO AFRICAN MOIST FORESTSFORESTS 162

7.1 Major resultsresults afterafter tenten yearsyears 164 77.2. 2 Findings and recommendations 164

CHAPTER IV - EVOLUTIONARY TRENDS AND NEEDS 168

1 . THE STUDY OF NEW SPECIES 168

2. THE /GROWTH RELATIONSHIP 168

3. PRODUCTION MODELS 169

4. STUDIES OF MIXED STANDSSTANDS 169

5. RELATIONSHIPS BETWEEN GENETICGENETIC IMPROVEMENT,IMPROVEMENT, SILVICULTURESILVICULTURE AND TECHNOLOGY 169

6. PLANTATION MANAGEMENT 170

CONCLUSIONCONCLUS ION 171

BIBLIOGRAPHY 177

1 . Bibliography onon enrichmentenrichment plantationsplantations 177

2. Bibliography on plantations inin clearedcleared areasareas 181 CHAPTER II

HISTORICAL SURVEYSURVEY

The first foresters responsibleresponsible for managing tropical forests (1900-1905 inin ,Nigeria, 1925-1930 inin the other African countries) hadhad the impression thatthat thethe closedclosed tropicaltropical forestforest waswas inexhaustibleinexhaustible andand thatthat naturenature itself took carecare ofof replenishingreplenishing itsits capital.capital. However, the progressprogress of knowledge on the composition and functioning of this ecosystem has disillusioned managers and,and, mostmost important,important, convincedconvinced themthem ofof thethe needneed forfor human interventionintervention inin thethe regenerationregeneration process.process.

The great diversitydiversity ofof environmentsenvironments andand thethe lengthinesslengthiness ofof responseresponse times in forestryforestry experiments, with their necessary replications, diddid not make the tasktask ofof thethe pioneerspioneers ofof tropicaltropical forestryforestry anyany easier.easier. Nonetheless,Nonetheless, thethe will to progress waswas rapidlyrapidly translatedtranslated intointo thethe applicationapplication ofof theoriestheories thatthat were to dividedivide thethe forestryforestry worldworld byby opposingopposing thethe conceptsconcepts of natural and artificial regeneration.regeneration.

At thethe samesame time,time, these disagreements enabled knowledge to evolveevolve separately.

There existexist aa greatgreat numbernumber ofof methodsmethods basedbased onon naturalnatural regeneration.regeneration. The'l'he basic principle isis "to"to graduallygradually permitpermit lightlight toto reachreach thethe ground floorfloor in order to trigger thethe germinationgermination ofof fallenfallen seedsseeds andand stimulatestimulate thethe growthgrowth of prepre-existing- existing plants languishinglanguishing underunder thethe canopy" (R.(R . CATINOT, 1965)1965). . These methods may be divideddivided inin twotwo mainmain groups,groups, according to theirtheir immediateimmediate objective:

- improvement techniques which do not immediately seek natural regeneration; in this case, stand homogeneity will be thethe easiereasier aspect to regenerate (improvement of OkoumeOkoum6 stands in , standardization according toto heightheight andand standardizationstandardization inin Zaire);Zaire);

- techniques aimed atat the immediate useuse of natural regeneration (improvement of naturalnatural stands in the CoteC8te d'Ivoire,d'Ivoire, tropical shelterwood systemsystem inin NigeriaNigeria andand Ghana).Ghana) .

Without going intointo detaileddetailed analysis,analysis, itit appearsappears thatthat thethe limitationslimitations of these practices areare duedue to:to:

- the difficulty of systematically applyingapplying andand controllingcontrolling thethe rightright dosage of lightlight forfor saplings;saplings;

- the wide scatteringscattering ofof activities,activities, and,and, as a corollary,corollary, thethe longlong

duration of the actions,actions I which leads to a dilutiondilution of human and financial efforts.

It was thusthus easyeasy forfor thosethose whowho supportedsupported artificialartificial regenerationregeneration toto claim that it is moremore efficient and less costlycostly toto concentrateconcentrate operationsoperations inin the field over a shorter period of time,time, and with systematicsystematic (hence(hence stricterstricter and easier) control. The deliberate choice of the field of action and of the species was another positivepositive element.element.

The goalgoal was to createcreate aa newnew forestforest byby replacingreplacing thethe pre-existingpre-existing standstand moremore or lessless rapidlyrapidly andand radically,radically, while regularizingregularizing its structurestructure byby plantingplanting one or two dominant species.species . -- 2 --

In the next section we shall examine the evolution of methods wherebywhereby a natural forestforest cancan bebe replacedreplaced withwith aa high-yieldhigh-yield artificialartificial stand; they range fromfrom relativelyrelatively limitedlimited enrichmentenrichment toto completecomplete replacementreplacement followingfollowing total clearing.clearing .

1 - DEFINITIONSDEFINITIONS

1.1 - Plant formations

Before beginning a study, it is importantimportant to make suresure thatthat thethe technical language isis understood by everybody. It is therefore necessary to define the terminology empemployedloyed oror refer to commonly used andand known definitionsdefinitions.. In thisthis case,case, we areare concernedconcerned withwith tropicaltropical AfricanAfrican plantp lant formationsformations.. TheseThese werewere inventoriedinventoried andand defined at the YangambiYangambi (Zaire)(Zaire) meetingmeeting of experts inin 1956.1956.

Here we shall briefly describe the formations involved in plantation works undertaken in thethe variousvarious countriescountries of westernwestern andand centralcentral Africa (R(R.. LETOUZEY,LETOUZEY, 1969).1969).

CClosedl osed forestsforests areare thosethose inin whichwhich thethe crowns ofof treestrees and shrubs touch.touch. The existence ofof suchsuch formationsformations directlydirectly dependsdepends onon thethe .climate . TheyThey maymay bebe grouped asas follows:follows:

+ or moist forestforest

"AII A closed stand with trees and shrubsshrubs ofof varying height;height; no grasses on the ground, but often suffruticose plants and, more rarely,rarely, non-non­

graminaceous, broad-leaved herbs."herbs. 11

The climate is constantly warm and moist;moist; annualannual averageaverage temperaturetemperature ranges fromfrom 2020 toto 27°C.27°C. TheThe annualannual saturationsaturation deficitdeficit isis weak;weak; itsits monthly valuevalue variesvaries little.little.

Within thethe categorycategory ofof moistmoist oror rainrain forestsforests wewe have:have:

* Moist evergreen forest,forest, wherewhere mostmost treestrees bearbear leavesleaves allall yearyear long.long. Cumulative annual rainfall ranges from 1 600600 toto 22 200200 mm.mm. TheThe drydry isis 2 toto 44 monthsmonths long.long.

* Moist semi-deciduoussemi-deciduous forest, where a great numbernumber ofof treestrees loselose their leaves during part of thethe .year. Annual rainfallrainfall rangesranges fromfrom 1 200 to 1 600600 mm; thethe drydry seasonseason lastslasts 44 toto 66 months.months.

+ Dry closedclosed forestforest

IIA"A closed stand with treestrees andand shrubsshrubs ofof varyingvarying heightheight (though(though usually shorter thanthan inin moistmoist forests);forests) i most upper-storeyupper-storey treestrees lose their leaves during part of the yearyear (in exceptionalexceptional casescases they may remainremain greengreen allall yearyear round:round: thisthis isis knownknown asas drydry evergreenevergreen forest);forest) i the undergrowthundergrowth consistsconsists ofof evergreen and deciduousdeciduous shrubs, and clumpsclumps of grassesgrasses are foundfound here andand therethere onon thethe

ground.ground." II - 3 3 -

Degraded forestforest beforebefore reforestationreforestation

The climate isis characterizedcharacterized by one or twotwo rainyrainy seasonsseasons withwith anan annual rainfall RR rangingranging fromfrom 11 000000 toto 11 600 mm. The may last 4 toto 88 months.months.

The qualitative floristicfloristic compositioncomposition ofof thesethese forestsforests alsoalso differs,differs, as well as certain quantitative aspectsaspects regardingregarding theirtheir potentialpotential inin termsterms ofof commercial species.species.

The plant formationsformations described above constitute thethe areaarea in which artificial enrichmentenrichment operationsoperations havehave beenbeen concentrated.concentrated.

Almost all of thethe earliestearliest trialstrials (dating(dating back to around 1910) were conducted in moist evergreen forests.forests.

11.2. 2 - The concept of enrichmentenrichment

Contrary to what thethe forestersforesters who firstfirst tackledtackled tropicaltropical forestsforests at the start of this century may have believed, the standing volume theythey containcontain is not very large.large . ItIt isis inin thethe order ofof 250250 to 300 cubic metres per hectare.

If one refersrefers toto thethe purelypurely merchantablemerchantable volume,volume, the figuresfigures fallfall sharply.sharply . OnOn average,average, they range fromfrom 55 to 25 cubiccubic metresmetres perper hectare,hectare, according toto the degree to which the forest is exploited,exploited, the commercialcommercial value of its specific composition,composition, andand thethe minimumminimum acceptedaccepted logginglogging diameter.diameter. - 4 -

This lastlast factorfactor hashas variedvaried considerablyconsiderably over time.time . When forestryforestry services firstfirst beganbegan operations,operations, itit appliedapplied toto aa relativelyrelatively limitedlimited numbernumber ofof species.species . However, thethe servicesservices soonsoon became concerned about the stands' loss of value and thethe needneed toto preventprevent it.it.

The main concern was thusthus to define and finalize appropriate forestryforestry actions to increaseincrease oror atat leastleast maintainmaintain thethe commercial-timbercommercial-timber potential of natural stands. WithinWithin thethe generalgeneral frameworkframework of forestforest management, the goal was to ensure highhigh yields,yields, asas homogeneoushomogeneous asas possible.possible. EnrichmentEnrichment becamebecame thethe way to save forests,forests, andand twotwo fundamentalfundamental optionsoptions tooktook shapeshape toto implementimplement it,it, dividing, as we have seen, the advocates of naturalnatural regeneration andand artificial regeneration.regeneration.

Here we shall discuss only methodsmethods whichwhich are applicableapplicable toto fairlyfairly largelarge plantations.

Forest,Forest. or "enrichment,"lIenrichment,1I plantations aim to introduce into a more or less transformed forestforest environment thethe valuable species which willwill eventuallyeventually constitute itsits essential output.output . Additional outputoutput maymay come from pre-existing valuable species,species, oror thosethose whichwhich havehave appearedappeared duedue toto naturalnatural regeneration.regeneration.

The earliest operations werewere quitequite cautious,cautious, andand involvedinvolved only the few species sure toto find outlets inin the export market [Niangon:[Niangon: Tarrietia utilis; Sipo: EntandrophraymaEntandrophragrna utile; Mahogany: KhayaKhaya spp.;spp.; Sapelli: EntandrophragmaEntandrophragrna cylindricum;cylindricllin; Okoum6:Okoume: AucoumeaAucoumea klaineana;klaineana i Iroko:Iroko: Chlorophora excelsa].excel sa] The

intention was toto "encouragelIencourage andand helphelp nature,nature, toto hastenhasten itsits work."work. II

Intervention onon original natural forests was subsequently intensified for commercial reasonsreasons (broadening(broadening thethe rangerange ofof regularlyregularly exportedexported species)species) and silviculturalsilvicultural reasonsreasons (better knowledgeknowledge of the characteristicscharacteristics and reactions ofof thethe relevantrelevant species).species).

Enrichment planting techniques may be classifiedclassified accordingaccording toto thethe degree of intervention andand alteration ofof the original ecosystem. Starting with minimal interventionsinterventions -- plantingplanting widely-spacedwidely-spaced straightstraight lineslines which did not overly disturb thethe environmentenvironment -- thesethese techniquestechniques havehave evolvedevolved towardstowards thethe gradual destructiondestruction ofof thethe pre-existingpre-existing naturalnatural forest.forest.

The original termterm "enrichment"II enrichment II hashas thusthus acquired a connotation that is both more destructivedestructive andand moremore intensive,intensive, inasmuchinasmuch asas itit isis veryvery difficult,difficult, if not impossible, toto transformtransform thethe forestforest ecosystem into a more productive system without resortingresorting toto methodsmethods thatthat resultresult inin aa totallytotally newnew ecosystem.ecosystem. In such cases, thethe interventionintervention isis actuallyactually aa conversionconversion plantation.plantation.

For its part,part, thethe FAOFAO CommitteeCommittee (1969)(1969 ) onon ForestForest DevelopmentDevelopment inin thethe Tropics (FDT)(FDT) recommendedrecommended thethe followingfollowing terminology:terminology:

II" _- Enrichment plantation:plantation: group or line planting, of varying intensity, designed toto improveimprove thethe percentage of desirable speciesspecies

in naturalnatural forests,forests I withoutwithout eliminatingeliminating existingexisting usefuluseful trees.trees . Natural regenerationregeneration formsforms aa significantsignificant portionportion of thethe cropcrop atat maturity.

- Conversion plantation:plantation : aa plantationplantation aimingaiming atat totaltotal replacementreplacement ofof pre-existing natural with a completelycompletely newnew man-mademan-made

forest.forest." II - 5 --

Yapo, OkouméOkoume andand NiangonNiangon mixedmixed forest,forest, 2525 yearsyears oldold (1963)(1963)

2 - EVOLUTION OF METHODS: FROMFROM ENRICHMENT TO TOTAL REPLACEMENT

Many methods havehave beenbeen triedtried outout withwith moremore oror lessless success,success, andand theythey have evolved over time,time, sometimessometimes with fewfew distinguishingdistinguishing features,features, soso thatthat we find transitionstransitions ratherrather thanthan sharpsharp boundaryboundary lineslines amongamong them.them.

We shall briefly describedescribe these methodsmethods in the order of their increasing transformationtransformation ofof thethe originaloriginal forest.forest.

2.1 - The line-plantingline- planting method

This is an extensive method which translatestranslates intointo aa fairlyfairly slow-goingslow-going enrichment thatthat producesproduces standstand homogenizationhomogenization onlyonly inin thethe longlong term,term, afterafter atat least twotwo rotations.rotations .

It consistsconsists ofof openingopening parallelparallel andand equidistantequidistant lines in thethe forestforest andand planting nursery-grown seedlingsseedlings ofof commercialcommercial speciesspecies atat regularregular intervals.intervals. The point isis to give the trees the benefit of extra light while remaining in a forest environment:environment :

all vegetation isis eliminatedeliminated fromfrom aa 2 2 metre-widemetre-wide strip;strip; - seedlings areare plantedplanted inin singlesingle filefile atat 2,2, 2.52.5 oror 5-metre5-metre intervals;intervals; - the lateral canopycanopy isis destroyeddestroyed moremore oror lessless intensely;intensely; - the seedlings are thinnedthinned outout earlyearly toto ensureensure theirtheir survivalsurvival andand avoid overlyoverly drawn-outdrawn-out tending.tending.

The method has evolved over time, and the distancedistance betweenbetween lines is nownow 20 to 25 m, leaving 88 to 10 metres between thethe treetopstreetops ofof adjacentadjacent lines.lines. AtAt the same time,time, all treestrees thatthat formform aa thickthick andand lowlow canopy which wouldwould preventprevent light from reaching thethe stripstrip areare girdled.girdled . -6-- 6 -

2.2 - TheThe modified line-planting method

In thethe precedingpreceding method, the narrownessnarrowness of the lines allowsallows a relativerelative light of only 7-87-8 percent. TheThe behaviourbehaviour ofof thethe speciesspecies involvedinvolved waswas notnot wellwell understood at thethe timetime thesethese actionsactions began. ItIt waswas onlyonly whenwhen theirtheir lightlight requirements were confirmed and taken into account that it became necessary to:

- limit the competition of the undergrowth for light by widening the lines, though not excessively, and still planting only one rowrow ofof seedlings inin eacheach line;linei

- increase incidental light by lowering the height of the inter-line stand (devitalizing(devitalizing itit with plant hormones).hormones) .

With a line 5 metres wide andand anan inter-lineinter-line stand whosewhose heightheight hashas beenbeen reduced to 1515 cm,cm, the result is 25 percent direct light and 35-40 percent lateral, forfor aa totaltotal ofof 6060 toto 6565 percentpercent relativerelative light.light.

The goal isis toto allowallow thethe saplingssaplings betterbetter initialinitial growthgrowth byby limitinglimiting competition atat anan earlyearly age.age.

In practical terms,terms, thethe techniquetechnique isis asas follows:follows:

- lines are 5 mm wide and set 10 toto 2020 mm apart,apart, accordingaccording toto thethe chosenchosen enrichment rate;rate;

- within thethe line,line, all trees whose diameter is less than 15 cmem are manually cut downdown atat kneeknee height;heighti this makesmakes it possiblepossible toto preserve a forestforest micro-environment at ground level while ensuring protection against invasioninvasion by undesirable pioneer species such as the Aga umbrella treetree (Musanga(Musanga cecropioides);

throughout the forest, all trees whose diameter is larger thanthan 15 cm are killedkilled byby fellingfelling oror girdling.girdling. The largestlargest treestrees areare oftenoften girdled or poisoned. TreesTrees whose diameter isis lessless than 5 cm do not much disturb laterallateral illumination;illumination;

- transplants are set inin singlesingle filefile withinwithin thethe lines,lines, at 3 metre intervals;

saplings are cleaned manually (climbers),(climbers), and regrowth is kept belowbelow their tops.tops.

Thanks toto thisthis method, itit isis possible to obtain about fifty well-grown valuable treestrees perper hectare,hectare, though permanent surveillancesurveillance and energeticenergetic intervention are required to ensure their protection against natural competitors.

2.32 . 3 -- The plot method

This method, usedused byby BelgianBelgian forestersforesters inin Zaire,Zaire, isis derived fromfrom thethe technique used byby AndersonAnderson toto reforestreforest ScottishScottish heaths.heaths . - 7 --

In this technique, thethe species which are toto regenerate are introducedintroduced with high-density plantings. SaplingsSaplings areare uniformly distributed over widely separated plots ofof equalequal area.area. InIn practicalpractical terms:terms:

- temporary nurseries are created beneathbeneath thethe forest,forest, toto accustom thethe transplants toto growinggrowing inin thethe shade;shade;

- 4 x 4 m squares are marked off, measuring 10 m from centre to centre in the fourfour cardinalcardinal directions;directions;

- all climbersclimbers andand herbaceousherbaceous undergrowthundergrowth are eliminatedeliminated from thethe squares, leavingleaving shrubsshrubs intact;intact;

the different formsforms of the desired species (seedlings,(seedlings, stumps and so on), are plantedplanted veryvery closeclose toto eacheach other;other;

- once thethe transplantstransplants havehave takentaken hold,hold, the shrubsshrubs areare graduallygradually eliminated, asas is,is, veryvery cautiously,cautiously, thethe overstorey.overstorey.

The goalgoal of this method is to avoid disturbingdisturbing the ecologicalecological environment andand immediatelyimmediately recreaterecreate thethe forestforest state for thethe newly-introducednewly-introduced species, while distributing thethe plotsplots widelywidely forfor economiceconomic reasons.reasons.

The relative light thereby obtained atat the level ofof thethe saplingssaplings hardlyhardly ever exceeds 5-105-10 percent.percent.

2.4 - The undergrowth method

This method isis basedbased onon partialpartial manualmanual destructiondestruction ofof thethe canopycanopy atat plantplantinging time.time.

Contrary toto whatwhat wewe shallshall seesee furtherfurther on,on, thethe objectiveobjective here isis toto preserve the lower storey, or undergrowth, between one line and the next, in order to accommodateaccommodate speciesspecies whichwhich cannotcannot taketake broadbroad sunlightsunlight immediatelyimmediately after planting, forfor instanceinstance thethe SipoSipo ((Entandrophragrna utile).utile).

Accordingly, thethe methodmethod consistsconsists ofof devitalizing treestrees thatthat make up the oveoverstorey,rstorey, opening planting lines,lines, andand temporarilytemporarily preservingpreserving partpart ofof thethe undergrowth between lines,lines , thenthen eliminating it gradually as the transplantedtransplanted seedlings grow.grow .

2.5 - Total andand gradual destructiondestruction ofof thethe forestforest byby devitalizationdevitalization

Under thisthis method,method, thethe pre-existingpre-existing forestforest is destroyed without the mechanical interventionintervention which would scrapescrape thethe soil away and allowallow secondary light-demanding species toto grow backback tootoo fast.fast .

2.5.1 -- The regrowth method

Upon planting, thethe seedlingsseedlings areare givengiven maximummaximum light,light, whilewhile thethe soilsoil is protectedprotected by preservingpreserving regrowth of shade-tolerant species. By covering the ground, the regrowthregrowth prevents the developmentdevelopment of thethe AgaAga umbrellaumbrella treetree (Musanga cecropioides) andand otherother weedweed species.species . - 8 -

This method includesincludes thethe followingfollowing operations:operations:

- all treestrees withwith aa diameterdiameter belowbelow 15-2015-20 cmem areare cutcut downdown manuallymanually atat knee height and left where they fall, without being burned. They are too small to require anyany cross-cutting;cross-cutting;

- trees which cannotcannot be cutcut downdown areare immediatelyimmediately devitalizeddevitalized with plant hormones. InIn actual fact, these trees, gradually eliminated by poisoning, at firstfirst formform aa thinthin canopy.canopy. OnceOnce dead,dead, theirtheir fallfall cancan cause significant damage toto thethe plantationplantation saplings;saplings; saplingssaplings areare transplanted at equalequal 4 to 6-metre6 - metre intervalsintervals inin straightstraight lineslines reopened manually inin thethe regrowth;regrowth;

- manual tendings,tendings, repeatedrepeated over aa 5-5- toto 8-yeara-year periodperiod accordingaccording toto

the speciesspecies 1 rate of growthgrowth andand targetingtargeting AgaAga umbrellaumbrella treestrees inin particular, keep the regrowthregrowth below thethe tops of the valuablevaluable species.

2.5.2 - The Martineau methodmethod (1930-32)(1930-32)

This method isis moremore onon thethe order of dense plantingplanting underunder forestforest cover.cover . It cautiouslycautiously introduces valuable species under a gradually-destroyedgradually-destroyed canopy. This was oneone ofof thethe firstfirst closed-plantationclosed-plantation methodsmethods conceivedconceived for African tropicaltropical closedclosed forests,forests, andand isis designeddesigned toto replacereplace thethe heterogeneousheterogeneous forestforest with a standstand consistingconsisting onlyonly ofof commercialcommercial species.species.

This techniquetechnique consistsconsists of:of :

- manually destroying all undergrowth with bole diameters less than 10 cm;cm;

- transplanting 22 500500 seedlings/ha,seedlings/ha, thenthen thinningthinning outout thethe saplings;saplings;

- gradually destroying the main canopycanopy by girdlinggirdling atat intervalsintervals ofof one, twotwo and fivefive yearsyears afterafter planting. SupplementarySupplementary lightlight isis thenthen ensured by sweeps made every five years startingstarting from the tenthtenth year.year .

Contrary to the preceding method, this proceeds by creating a closed plantation beneathbeneath aa canopy,canopy, withwith gradualgradual thinningthinning afterafter planting.planting.

2.62 . 6 - Total destruction ofof thethe forestforest beforebefore plantingplanting

The whole forestforest canopycanopy isis removedremoved inin aa singlesingle operation,operation, inin orderorder toto give thethe transplantstransplants fullfull lightlight rightright fromfrom thethe start.start.

2.6.1 - The Taungya method

Plots in government-ownedgovernment-owned forestlandforestland areare temporarilytemporarily grantedgranted toto farmers to establish an association ofof forestforest treestrees andand intercrops.intercrops.

The goalgoal herehere is to associateassociate agricultureagriculture andand forests. FarmersFarmers benefitbenefit by having the use of the land for severalseveral years,years, forestersforesters by lowerlower plantationplantation and tendingtending costs.costs. - 9 -

Tree spacingspacing dependsdepends veryvery muchmuch onon thethe choicechoice ofof interplantedinterplanted crop;crOPi usually greater thanthan 55 xx 55 m.m.

Saplings transplantedtransplanted byby oneone or the other partnerpartner thus profitprofit fromfrom goodgood growth conditions duringduring thethe twotwo oror threethree yearsyears ofof thethe cultivationcultivation period,period, after which thethe forestryforestry serviceservice resumesresumes tendingtending operationsoperations forfor asas longlong asas necessary.

This agro-silviculturalagro-silvicultural system, which usually favoursfavours thethe forestryforestry side, is an economicaleconomical way to reforest land that might otherwise be lost to the forest domain inin thethe longerl onger run.run.

In exchangeexchange for their work, farmers have the right to till andand disposedispose of their crops,crops, andand maymay havehave socialsocial benefitsbenefits oror economiceconomic incentivesincentives asas well.well. Their main advantageadvantage isis temporarytemporary accessaccess toto thethe forestforest andand itsits fertilefertile land.land. The Taungya method hashas producedproduced goodgood resultsresults inin areas where fertilefertile land isis scarce.

2.6.22.6 . 2 -- The LimbaLirnba methodmethod

The Limba (Terminalia superba)superba) grows inin fullfull sunlight,sunlight , veryvery straight,straight, and doesdoes notnot needneed toto bebe pruned.pruned. It is thereforetherefore unnecessary to preservepreserve accompanying regrowthregrowth oror planplan veryvery closeclose plantations.plantations.

Old FramiréFramire plantation (20(20 years old)old) atat SangouéSangoue - 10 -

The pre-existingpre-existing forestforest isis completely destroyed soso thatthat the transplants can get well rootedrooted beforebefore thethe drydry seasonseason setssets in.in. InIn thisthis technique:technique:

- all trees with a diameter inferiorinferior toto 3030 cmem areare felledfelled manually;manually;

- all trees with a diameter aboveabove 3030 cmem areare girdled oror poisoned;poisoned;

- all residues areare burned;burned;

- planting lines are opened inin thethe burnt wastes;wastes;

- Limba stump plants, 1-1.51-1.5 m tall, are plantedplanted at definitive intervals of 12-14 m or, ifif futurefuture selectionselection isis planned,planned, semi-definitive intervalsintervals ofof 66 xx 1212 m.m.

2.6.32 . 6.3 - Methods based on mechanized

The preceding methodmethod waswas adaptedadapted toto plantationsplantations of of Okourn6 Okoume (Aucournea(Aucoumea klaineana), thethe onlyonly difference beingbeing mechanizationmechanization ofof thethe clearingclearing process.process.

Trees with a diameter inferior to 30 cmem are felled byby bulldozersbulldozers whose power isis appropriateappropriate forfor thethe kindkind ofof originaloriginal growth;growth; largerlarger treestrees areare devitaldevitalized.i zed. Remnants are windrowed and buburned,rned, and the transplants are set between thethe windrows.windrows. TheThe choicechoice ofof plantingplanting intervalsintervals isis moremore varied,varied, sincesince the ground isis totallytotally cleared.cleared. TendingTending operationsoperations are importantimportant but lessless vigorous, because'because" thethe soilsoil has already been scraped.scraped.

This method is nownow usedused forfor manymany otherother speciesspecies asas well:well: TerminaliaTerminalia ivorensis, T. superba, Samba (Triplochiton(),scleroxylon), and soso on.on. Today,Today, more powerful equipmentequipment makesmakes itit possiblepossible toto fellfell allall treestrees mechanically.mechanically .

3 - EXAMPLES OF APPLICATION OF THETHE METHODS DESCRIBED

Soon after thethe establishmentestablishment ofof forestryforestry servicesservices inin westernwestern Africa,Africa, resource managers brought toto notice thethe problems causedcaused by the heterogeneous composition and regeneration ofof Africa'sAfrica 's tropicaltropical closed forests. Artificial enrichment and environmental homogenization operations were therefore undertaken inin thethe variousvarious countriescountries involved.involved .

33.1.1 -- CoteCate d'lvoired'Ivoire

Starting in 1930-31,1930-31, tightly-spaced forestforest plantations were established in the YapoYapo forest,forest, about fiftyfifty kmkm northnorth ofof AbidjanAbidjan (Martineau(Martineau method).method). AnAn area of 90 ha was enriched with Niangon (Tarrietia(Tarrietia utilis) wildings planted at 2 x 2 mm intervals, for a total of 2 500 trees per hectare. TheThe area isis thethe natural environment of this species. Other species such as Mahogany ((Khaya ivorensis),ivorensis) , Dibetou ((Lovoa trichilioides) and Tiama ((EntandrophragmaEntandrophragma angolense) have alsoalso beenbeen introducedintroduced inin smallsmall proportions.proportions.

A 19851985 inspectioninspection ofof thethe plotsplots showedshowed thatthat thethe results,results, thoughthough notnot spectacular, were relatively satisfactory. OnOn two plotsplots coveringcovering anan areaarea ofof 23 ha, the residual density of the Niangons (Tarrietia utilis)uti/is) is 9090 to 131300 plants per ha (diameter(diameter over 30 em);cm); the trees often seem weakweak.. From observations mademade overover thethe lifetimelifetime ofof thesethese stands,stands, itit appearsappears that:that: - 11 -

- The original canopy was definitely removed too late.late . Several trees belonging toto secondarysecondary speciesspecies still dominateddominated thethe 30-year-old30 - year-old stand.

- The stand waswas firstfirst thinnedthinned whenwhen itit waswas alreadyalready 25-3025-30 yearsyears old.old. AtAt that advanced age, the remaining trees can no longer react dynamically, and may be tootoo weak toto survivesurvive badbad weatherweather (greater(greater risk of windfalls).windfalls) .

- The endings were carried outout regularlyregularly duringduring thethe firstfirst eighteight years,years, and irregularly thereafter.thereafter.

A few yearsyears later, for economic as wellwell asas otherother reasons,reasons, lineline plantingplanting was started. The lineslines were setset 1010 m apart, with planting intervals of 5 or 2.5 m along the lineslines (making(making aa totaltotal ofof 200200 oror 400400 transplantstransplants perper ha).ha).

Until 1948, thethe plantations hadhad benefited byby a regular spacing of 25 m between lines, withwith planting intervalsintervals ofof 22 or 2.5 m along the lines, makingmaking a total of 160-200160-2 00 transplantstransplants perper ha.ha . TheThe transplantedtransplanted speciesspecies werewere stillstill Niangon (Tarrietia(Tarrietia utilis),utilis), MahoganyMahogany (Khaya(Khaya ivorensis),ivorensis), andand DibetouDibetou (Lovoa(Lovoa trichilioides), with the addition of FramireFramir6 (Terminalia ivorensivorensis)is) and BosseBosse (Guarea cedreta).cedreta). About 1111 000000 haha werewere treatedtreated inin thisthis way.way.

Mixed methodsmethods have alsoalso beenbeen usedused toto enrichenrich plotsplots wherewhere naturalnatural regeneration was consideredconsidered insufficient.insufficient. In particular,particular, Mahogany (Khaya(Khaya ivorensiivorensis)5) has been planted at intervalsintervals of 10 x 5 m, with a certain degree of flexibility thatthat enablesenables eacheach transplanttransplant toto benefit fromfrom thethe best living space that can bebe obtainedobtained withwith aa minimumminimum ofof interventionintervention onon thethe originaloriginal forest.

The Taungya method has been used inin different periods, but only to a very limitedlimited extentextent inin closedclosed forestforest areas.areas.

Trial species were Frak6Frake (Tenninalia(Terminalia superba),superba), FramiréFramire (Terminalia() and Samba (Triplochiton scleroxylon). Initial results were promising, butbut becamebecame veryvery unevenuneven atat aa more advanced age.age. BetterBetter resultsresults werewere achieved in areas, particularly withwith TeakTeak ( grandis), Gmelina (Gmelina arborealarborea) and Cassiacassia (Cassia(Cassia siamea).siamea).

Since the 1960s, preference has been given to plantations in cleared areas. ThisThis techniquetechnique has beenbeen chosenchosen particulaparticularlyrly forfor light-demandinglight-demanding speciesspecies such as: Frak6Frake (Terminalia(Terminalia superba),superba), FramiréFramire (Terminalia(Terminalia ivorensis),ivorensis), SambaSamba (T(Triplochitonriplochiton scleroxylon),scleroxylon) , Teak (Tectona(Tectona grandis),grandis) , CedarCedar (Cedrela(Cedrela odorata),odorata) , and so forth.forth .

3.2 - Nigeria

Nigeria's foresters became concernedconcerned at an earlyearly datedate toto ensureensure thethe artificial regeneration of closedclosed forests.forests. SinceSince 1916,1916, loggers have been required to plant 2424 saplingssaplings forfor eacheach felledfelled adultadult tree;tree; a praiseworthy requirement in itself, but difficultdifficult toto monitormonitor becausebecause ofof thethe far-rangingfar-ranging operations and operators it entails. The transplants could not be systematically defended fromfrom naturalnatural vegetation,vegetation, and few tracestraces of themthem remain. - 12 -

TheThe line-planting method was usedused duringduring thethe 1930s,1930s, but with fewfew variations asas regardsregards placementplacement and,and, mostmost important,important, withwith littlelittle attentionattention toto tending and light dosage. ItIt has thus beebeenn impossible to draw any interesting conclusions fromfrom thesethese efforts.efforts.

LaterLater on, towards the 1950s,19505, the Taungya method was employed onon aa large scale for both short-rotationshort-rotation species such asas CassiaCassia siameasiamea andand EucalyptusEucalyptus

spp. andand longer-livedlonger-lived species such as TeakTeak (Tectona grandis)grandis), I Terminalia spp.,spp., and Bilinga (Nauclea(Naucl ea trilesii).trilesii).

Plantations consistedconsisted ofof mixedmixed oror purepure stands.stands.

In mixedmixed stands, shade-tolerant speciesspecies -- essentially Mahogany'Mahoganyl - werewere introduced, with aa 4-metre4-metre spacingspacing forfor shortshort stumpstump plantsplants or,or, sometimes,sometimes, forfor striplings (whole(whole treestrees withwith onlyonly thethe twotwo terminalterminal leavesleaves leftleft on).on) .

In purepure stands,stands, the spacingspacing becamebecame 6 x 6 m, especiallyespecially for thethe introduction ofof Bilinga andand Terminaliaspp.Terminaliaspp. OneOne overalloverall tendingtending isis carriedcarried out the second year, andand saplingssaplings areare thinnedthinned outout onlyonly onceonce beforebefore thethe sixthsixth year.year.

A clearing isis plannedplanned forf or thethe 11th11th year,year, oror earlierearlier ifif necessary.necessary.

At present, plantings needed toto re-establish destroyeddestroyed forestsforests areare mademade inin full sunlight on totally-cleared areas andand mechanically-prepared .soils.

3.3 - CameroonCamerOon

Artificial enrichment waswas launched quite early inin thisthis country, particularly inin thethe MbalmayoMbalmayo forestsforests andand thethe Makak-NyongMakak-Nyong reserves,reserves, andand itit hashas been pursued inin otherother regions.regions.

In the MbalmayoMbalmayo forest,forest, thethe line-plantingline-planting method has been employedemployed since 1932 forfor speciesspecies suchsuch asas AyousAyous (or(or Samba:Samba: TriplohitonTriplohiton scleroxylon),scleroxylon), Mahogany (Khaya ivorensis), Sapelli (Entandrophragma(Entandrophragma cylindricum),cylindricum), Bibolo (or(or Dibetou:Dibetou : Lovoa trichilioides), and soso on.on.

After 18 years, only 48 percent of the transplanted saplings were stillstill standing,standing, but there was a significant additional amount of natural regeneration whichwhich broughtbrought thethe numbernumber ofof valuablevaluable treestrees upup toto 7575 percentpercent ofof those planted. Moreover, thethe contributioncontribution fromfrom natural regeneration ledl ed the forestry services toto changechange theirtheir enrichmentenrichment method,method, encouraging naturalnatural regeneration.regeneration . This was done on one-hectare plots in conjunction withwith controlled cultivation.cultivation. TheseThese plots,plots, groupedgrouped inin 100100 toto 300-ha300-ha sections,sections, werewere bounded by lines planted with Mahogany (Khaya ivorensis)ivorensis),, Sapelli (Entandrophragma cylcylindricum) indri cum) snd Bibolo (Lovoa(Lovoa trichilioides).trichilioides) .

In the Makak-Nyong reserve, 2 500 ha were planted in the periodperiod from 1932 to 1949 withwith. .the the following species:species , Sapelli (Entandrophragma cylindricum),cylindricum) , Mahogany (Khaya(Khaya ivorensis),ivorensis) , Bibolo (Lovoa(Lovoa trichilioides),trichilioides) , Iroko {Milicia(),excelsa) , Bosse"Bosse (Guarea cedrata), Ayous (Triplohiton(Triplohiton scleroxylon),scleroxylon), Kosipo (Entandrophragma(Entandrophragma candollei),candollei) , etc.

Mahogany (Khaya(Khaya ivorensis,ivorensis, KhayaKhaya anthothecaanthotheca and and ¡(haya Khaya grandifolia)grandifolia) tolerate andand growgrow fasterfaster inin fullfull sunlight.sunlight. - 13 -

Here too, the line-plantingline-pl anting memethodt hod was notnot veryvery suitabsuitablel e forfor strstrictlyi ctly light-demanding species.species . TheThe bestbest resultsresul ts were achievedachieved withwith MahoganiesMahoganies (Kbaya(Khaya spp.), Dibetou (Lovoa trichilioides) and Sapelli (Entand(Entandrophragmar ophragma cylindricum), inin decreasingdecreasing order.order .

InI n thethe coastalcoastal areaarea ofof the ,south, OkoumeOkoumé plantationsplantations have beenbeen establishedestablis h ed alongalong thet h e samesame lineslines asas the enrichment pprogrammesr ogrammes of neighbouring Gabon.

AroundAr ound 1975,1975, thethe wide-linewide- line methodmethod waswas usedused againagain onon anan experimentalexperimental basis inin thethe easterneastern semi-deciduoussemi-deciduous forestforest (Belabo)(Belabo) andand thethe coastalcoastal closedclosed forests. Five-metre-wideFive-metre-wi de lineslines werewere setset 15-20 m apart, with 33-metre- metre iintervalsntervals between treestrees alongalong eacheach line.line. TheThe undergrowthundergrowth waswas cutcut downdown atat kneeknee height,height, and all treestrees withwith aa diameterdiameter overover 2020 cmem werewere girdledgirdled oror poisoned.poisoned.

The species plantedp l anted were TerminaliaTerrninalia ivorensis and T. superba, Entandrophragma cylindricum andand E.E . utile, Khaya ivorensis, Triplohiton scleroxylon, Tarrietia utilis,utilis, AfzeliaAfzelia africana,africana, LovoaLovoa trichilioides, etc.

3.4 - Congo

In this country, attention focused early on the LimbaLimba treetree (Te(Terminalia minalia superba) bebecausecause of its rapid growth andand thethe quality ofof itsits wood.wood .

In 1937,1937, closed plantations werewere mademade on smallsmall plotsplots toto serveserve asas arboreta.arboreta .

Later, lineline plantingsplantings werewere made,made, withwith thethe transplantstransplants setset atat 1010 xx 5 5 m m intervals. These initial experiments showed thatthat the Limba tree cancan growgrow straight and isis self-pruning.self- pruning . AtAt thethe beginningbeginning ofof thethe 1950s,19505, itit was therefore determined toto plantplant itit atat thethe definitivedefinitive spacingsspacings ofof 1212 xx 1212 mm oror 1212 xx 1414 m.m.

The Limba, a light-demanding species, requires completely open space.space . This was provided inin twotwo stages:stages:

- the chosen ground,ground, already heavily logged, was totally clearedcleared alongalong a largely open strip;strip;

- tall stump plants werewere transplanted;transplanted;

- the trees of the upper canopycanopy were girdled thethe followingf o llowing year;year;

- the lines were cleaned five times the first year and three or four times the second year, toto keepkeep thethe crownscrowns ofof thethe transplantstransplants freefree from other vegetation and to prevent creeper invasions.invasions. This method was later replaced with planting in full sunlight after mechanized forest clearingclearing andand soilsoil preparation.preparation.

3.5 - Ghana

The line-plantingline-plan t i ng methodmethod hashas also been used inin evergreenevergreen closedclosed forests, in areasareas wherewhere extremelyextremely heavy forest logging left no hope forfor natural regeneration.regeneration . - 14 -

Lines areare openedopened 1.801.80 m widewide andand 2020 mm apart,apart, andand climbersclimbers growinggrowing within 5 metres ofof bothboth sidessides ofof thethe lineline areare eliminated.eliminated. The canopycanopy is gradually reducedreduced byby poisoning,poisoning, enoughenough toto give thethe saplings light without much risk of stimulatingstimulating climberclimber growthgrowth withwith surplussurplus light.light. TheThe transplantstransplants areare spaced 55 mm apart,apart, and are at leastleast 11 m m tall,tall, to avoid being damaged by wildlife. The species plantedplanted areare Mahogany (Khaya ivorensis),ivorensis) , Sapelli

(Entandrophragma cylindricum),cylindricum) I Tiama (Entandrophragma angolense)angolense), I NiangonNiangon (Tarrietia utilis),utilis), andand soso forth. For MahoganyMahogany and some other species, the results obtained withwith line-plantingline-planting areare betterbetter thanthan withwith closeclose spacing.spacing.

Block plantations have also beenbeen createdcreated withwith Framir6Framire (Terminalia(Tenninalia ivorensis) and Niangon (Tarrietia(Tarrietia utilis), spaced at intervals of 5 x 6 6 m.m. Towards thethe endend ofof thethe 1960s,1960s, largelarge areasareas werewere enrichedenriched (about(about half ofof themthem with the Taungya method andand half with the regrowth method) with species such as SambaSamba (Triplohiton scleroxylon),scleroxylon), FramiréFramire (Tenninalia(Terminalia ivorensis),ivorensis), Teak (Tectona grandis), CedarCedar (Cedrela(Cedrela odorata),odorata), andand soso forth.forth.

3.6 -- Zaire

As regards this country, it is necessarynecessary toto distinguishdistinguish methodsmethods appliedapplied within the framework of extensiveextensiv e programmes from those used on an experimental basis.basis . InIn effect,effect, BelgianBelgian scientistsscientists were veryvery activeactive inin thisthis work before Zaire'sZaire I s independence, mainlymainly atat the Yangambi site. ManManyy techniquestechniques werewere tested,tested, includinginc luding thethe following:following:

Enrichment by uniformizationuniformization atat groundground levellevel

This method isis a special application of the silvo-agricultural systemsystem and differs fromfrom thethe TaungyaTaungya methodmethod inin thatthat saplingssaplings belongingbelonging toto valuableval uable species areare identified andand preserved atat the time the land isis putput underunder cultivation (essentially(essentially with with banana-treesbanana-trees at at first,first, thenthen coffee,coffee, thenthen cocoa),cocoa) , simultaneously plantingplanting somesome oneone hundredhundred TerminaliaTenninalia superbasuperba perper hectare.hectare. TheThe stand resulting from thisthis method should be a heterogeneous secondary forest whose overstorey includes,includes, besidesbesides TeiminaliaTenninalia superba,superba, the valuable species that were sparedspared whenwhen thethe landland waswas putput underunder cultivation,cultivation, as wellwell as economically importantimportant speciesspecies thatthat regeneratedregenerated naturally.naturally.

Where there was no regrowth of valuable specspecies,ies , the simple forest/banana methodmethod was applied. After thethe landland waswas cleared,cleared, generally without burning, LimbaLimba treestrees were plaplantednted at 6 x 12 mm intervalsintervals intercroppedintercropped with banana trees.trees. TheThe periodperiod ofof cultivationcultivation waswas supposedsupposed toto bebe limitedlimited toto 5 or 7 years. It was often extended withwith permanentpermanent coffee and cacaocacao plantations which areare stillstill toto bebe foundfound therethere today.today. TheThe LimbaLimba plantationsplantations have seldom been thinnedthinned out; exploitation begins after 40-45 years, when their average diameterdiameter reachesreaches 6060 cm.cm.

Line enrichmentenrichment

This hashas alsoalso beenbeen testedtested atat differentdifferent intensities.intensities . ExperienceExperience hashas shown that this method isis better suitedsuited forfor enrichingenriching fairlyfairly openopen formations,formations, or even fallows, than established forests which are exploited little or notnot at all.all. This methodmethod hashas producedproduced goodgood resultsresults withwith fast-growing,fast-growing, light­light- demanding species, which develop a nnormalormal shape eveneven whenwhen isolatedisolated (Terminalia - 15 -

Spp'/spp., for exampexample).l e). In 19871987-89,- 89, limitedl imited lineline-planting- p l anting programmes were resumed in the Mayumbe forestforest reserves.reserves .

Success has beenbeen veryvery limited,limited, forfor wantwant ofof thethe resourcesresources neededneeded forfor intensive forestryforestry care.care.

WideWide-strip- strip planting

Strips 10 m widewide andand 25-5025-50 mm longlong areare cutcut everyevery 50SO mm (10(IO aresares perper hectare) and planted with one principal species (Entandrophragma,(Entandrophragma, Autranella) plusp l us accompanying species,species, atat intervalsintervals ofof 44 x x 4 4 m,m, 2 x 2 mrn or 11 xx 11 m.m.

Direct seedingseeding inin narrownarrow stripsstrips afterafter thoroughthorough cleaningcleaning

This method consists ofof meticulously cleaningcleaning stripsstrips 22 m wide and 20 m apart, clearedcleared ofof allall naturalnatural rootroot tangle.tangle. SixSix seedsseeds perper m2m2 are planted everyevery 2 m (Entandrophragma spp.,SPP" MiliciaMilicia excelsa,excelsa, Tarrietia utilis, CeibaCeiba spp.,SPP'I Khaya spp.)spp.). . Results vary according toto the species. Growth is quitequite comparablecomparable to that obtained with lineline planting, butbut seedingseeding allowsallows higherhigher densitydensity andand aa somewhat better shape than transplanting, the possibilities of quality wood yields areare greater,greater, andand thethe latitudelatitude forfor selectionselection byby thinningthinning isis wider.wider.

The plot method

This method,method, inspiredinspired byby Anderson'sAnderson's plots,plots, originallyoriginally consistedconsisted of planting largelarge plots,plots, sized from one toto manymany ares,ares, underunder standsstands ofof AgaAga umbrella treestrees (old(old wildland);wildland) i thethe undergrowthundergrowth waswas clearedcleared andand seedlings werewere planted with spacingspacing varyingvarying fromfrom 44 x x 4 4 m m toto 11 x x 1 1 m.m. TheThe resultsresults achieved,achieved, especially withwith spacingspacing ofof 11 xx 1 1 m or even 2 x 22 m,m, promptedprompted BelgianBelgian foresters to develop thethe tightlytightly spacedspaced plotplot methodmethod (E.(E. MAUDOUX,MAUDOUX, 1958). This method aimed to combine the biological advantages of tightly-spaced planting with the lower costs of extensiveextensive enrichment methods. Small groupsgroups ofof saplings are transplanted oror sownsown fairlyfairly closeclose together,together, withwith thethe groupsgroups widelywidely scatteredscattered over thethe areaarea toto bebe enriched.enriched. ThisThis principleprinciple hashas beenbeen adaptedadapted toto differentdifferent environments andand hashas producedproduced goodgood resultsresults inin openopen environmentsenvironments (moors,(moors, openopen savanna, deforested land),land), but in closedclosed forestsforests it has met the same difficulties ofof canopy opening, regrowth control and plantplant tendingtending encounteredencountered in llineine planting,planting, with the additionaladditional problem of widelywidely scatteredscattered sites, which makes accessibility moremore difficult.difficult.

Enrichment in clear fellingfel l ing areasareas

This method is usedused onlyonly inin areasareas fullyfully exploitedexploited forfor fuelwoodfuelwood oror lumber.l umber. The forest fallow is enriched with valuable species by plantingplanting light­light- demanding species suchsuch as TerminaliaTerminalia superba,superba, Milicia (Chlorophora)(Chlorophora) excelsa and so forth,forth, uniformly spaced at 10 x 1010 m oror 1515 xx 1010 m.m. ItIt isis hopedhoped thatthat regrowth will guardguard thethe valuablevaluable treestrees introduced.introduced. ProblemsProblems inin controllingcontrolling this regrowth andand tendingtending thethe planted saplingssaplings havehave appearedappeared withwith thisthis method as well.well .

In conclusion, of all these methods testedtested inin actual practice, onlyonly thethe first two - the "uniformizationlIuniformization at ground level"level ll or "LimbatlLimba method,method," 11 and the "lineIIline enrichment"enrichment tl methodmethod - have beenbeen appliedapplied toto fairlyfairly extensiveextensive areas,areas, - 16 -

especially in Mayumbe, butbut were later abandoned for historical reasons. It has not been possible toto obtainobtain recentrecent informationinformation onon theirtheir results.results.

3.7 -- Other countries:countries: Guinea.Guinea, ,

The other West African countriescountries havehave applied,applied, onon aa relativelyrelatively modestmodest scale, techniques testedtested oror perfectedperfected elsewhere.elsewhere.

In Guinea, lineline enrichmentenrichment has been carriedcarried outout inin severalseveral reservedreserved forests, butbut it has notnot beenbeen possiblepossible toto learnlearn eithereither thethe extentextent oror thethe results of these plantations.plantations.

In SierraSierra Leone,Leone, various natural stand improvement techniques havehave beenbeen used. On the one hand, techniques favouring natural regeneration,regeneration, suchsuch asas thethe Tropical Shelterwood System (TSS)(TSS) also used in Nigeria and Ghana, have been applied at a raterate ofof manymany hundredshundreds of hectareshectares a year; at thethe endend ofof thethe 1950s, the area so treated amounted to 4 000 ha. On the other hand, methodsmethods involving planting inin thethe strictstrict sensesense werewere appliedapplied onon aboutabout 55 000000 haha inin 1960,1960, but statistics notnot distinguishdistinguish amongamong intensiveintensive planting,planting, TaungyaTaungya method,method, under-cover planting andand lineline planting.planting. TheThe resultsresults areare notnot known.known. However,However, methods which were tootoo extensively spreadspread out,out, line enrichment inin particular, were abandonedabandoned atat thethe beginningbeginning ofof thethe 1960s1960s duedue toto strongstrong agriculturalagricultural pressure on thethe land.land.

Lastly, except forfor aa fewfew trials,trials, nono naturalnatural forestforest improvementimprovement oror enrichment system has been established in Liberia. As of 1977, the Forestry Development Authority'sAuthorityfs plantationsplantations coveredcovered 55 500500 haha (pines,(pines, Teak,Teak, Gmelina,Gmelina, etcetc.).. ) .

4 - KNOWLEDGEKNOWLEDGE ACQUIREDACQUIRED

4.14 . 1 - - The lightlight factorfactor

In the forestforest environment whichwhich interestsinterests usus here,here, itit soonsoon became clearclear that light was the growth-limitinggrowth-limiting factor affecting saplings.saplings. ItIt isis true that this fact waswas notnot apparentapparent in thethe forestforest environment,environment, thoughthough A.A. AubrevilleAubreville hadhad noted that "GrowthIIGrowth depends in very largelarge measure on the quantity of light received byby the crown.crown. Obviously no one could doubtdoubt this, but withinwithin thethe constantly moist and warm tropical rain forest environment it was thoughtthought that plants couldcould developdevelop eveneven underunder poorpoor light."light. II

Initially inadequateinadequate knowledge of the behaviourbehaviour ofof economically valuable species underestimated the importanceimportance ofof light.light. ResearchResearch andand thethe development of forestryforestry techniquestechniques subsequentlysubsequently showedshowed thatthat resultsresults dependdepend essentially on thethe amountamount ofof light,light, especiallyespecially forfor youngyoung plants.plants.

Though lightlight helpshelps thethe growthgrowth ofof newly-introducednewly-introduced species,species, it alsoalso powerfully stimulates aa wholewhole rangerange ofof invasiveinvasive speciesspecies whosewhose developmentdevelopment isis very damaging to the saplings.saplings. ParticularlyParticularly aggressiveaggressive pioneerpioneer species,species, suchsuch as the Aga umbrella tree,tree, tendtend toto occupyoccupy opened opened areasareas veryvery fast.fast.

The care of saplings thusthus requires a good balance between light dosage and keeping natural vegetationvegetation atat aa suitablesuitable distance.distance. -- 17 --

4.2 - Choice of speciesspecies

The earliest enrichmentenrichment operationsoperations werewere carriedcarried outout atat aa timetime when the number ofof economicallyeconomically valuablevaluable speciesspecies (those(those whichwhich hadhad aa permanentpermanent market)market) was limited.l i mited. Accordingly,Accordingly, thesethese werewere thethe speciesspecies toto which priority waswas givengiven tot o enrichenrich forestsforests toto whichwhich theythey werewere nativenative butbut whichwhich hadhad beenbeen greatlygreatly impoverishedi mpoverished by intensiveintensive logging,logging, or toto increaseincrease the value of stands where theythey werewere absent:absent : MahoganiesMahoganies (Khaya(Khaya spp.),spp.) I NiangonNiangon (Tarrietia(Tarrietia utilis),utilis) I SipoSipo (Entandrophrayma(Entandrophragma uti/e),utile), Sapelli (Entandrophrayma(Entandrophragma cylindricum).cyl indri cum)

Two factorsfactors thenthen broadenedbroadened thethe choice:choice: onon thethe oneone hand,hand, thethe numbernumber ofof commercial speciesspecies increased;i ncreased; onon thethe other,other, forestersforesters realizedrealized thethe need toto use light-demanding speciesspecies forfor plantations.plantations. TerminaliaTerminalia spp., Teak, Gmelina and so foforthr th thusthus appeared. However,However , priority isis still given toto valuable commercialcommerci al species which,which, eveneven ifif onlyonly smallsmall numbersnumbers survivesurvive afterafter strictstrict selection, often moremore naturalnatural thanthan human,human, greatlygreatly enhanceenhance thethe perper hectarehectare valuevalue..

With canopycanopy stillstill relativelyrelatively thick,thick, thethe introductionintroduction ofof ,Mahoganies, Niangon, DDibetou,i betou, Tiama, Sapelli, Sipo andand SambaSamba accordinglyaccordingly continued.continued. Gradual clearing enabledenabled forestersforesters toto introduceintroduce eveneven moremore light-demandinglight-demanding species such asas TerminaliaTe~inalia spp. andand Okoumé.Okoume.

Total replacementreplacement has alsoalso ledled toto thethe introductionintroduction ofof fast-growingfast-growing species yielding secondary-gradesecondary-grade timbertimber butbut withwith shortershorter fellingfelling cycles. ThisThis is thethe casecase ofof pinepine (Pinus(Pinus caribaea),caribaea), GmelinaGmelina andand EucalyptusEucalyptus trees,trees, whosewhose initial uses forfor lumberlumber oror fuelwoodfuelwood maymay evolveevolve towardstowards thatthat ofof commercialcommercial timber.

The Taungya method hashas alsoalso mademade itit possible toto plantplant speciesspecies suchsuch asas Terminalia, Samba,Samba, Cassia,Cassia, Teak,Teak, Gmelina,Gmelina, andand soso forth,forth, inin clearedcleared areasareas withwith no competition.

4.3 -- Results

The saplings which have survived inin the various trials are those which have benefited fromfrom betterbetter lightinglighting andand intensiveintensive clearingclearing ofof thethe naturalnatural vegetation.

GeneraGenerallylly speaking, enrichment operations havehave not been a completecomplete success. The earliest line plantings suffered from a overlyoverly thickthick canopycanopy andand from strong undergrowth andand regrowthregrowth competition.competition. WhenWhen thethe lineslines werewere widened,widened, however, competition, especiallyespecially fromfrom climbers,climbers, becamebecame veryvery intense.intense. TendingTending and cleaning operations became very numerous and repetitive. The more light isis given toto introducedintroduced plants,plants, the more necessarynecessary itit is to controlcontrol thethe development of potential competitivecompetitive vegetationvegetation (even(even moremore soso inin the regrowth method, where accompanying vegetation must never be allowed toto getget thethe upperupper hand)hand). .

TheThe success of the variousvarious methods has thus been influencedinfluenced by thethe

forestersforesters' I perseverance inin protectingprotecting thethe treestrees theythey havehave planted;planted; however,however, theirtheir perseveranceperseverance has often beenbeen curbedcurbed byby thethe lacklack ofof personnel and money.money. Thus there are limitslimits toto thisthis technique,technique, which, as regardsregards extensive forestforest treatment, shouldshould bebe applicable toto large areas with a veryvery lowlow financialfinancial investment in material and humanhuman resourcesresources perper unitunit ofof area.area. Paradoxically,Paradoxically, - 18 -

it hashas becomebecome almostalmost as costlycostly asas intensiveintensive plantationsplantations whichwhich concentrateconcentrate high productivity inin smallsmall areas.areas.

Many forestryforestry operationsoperations andand investmentsinvestments were interruptedinterrupted during the

Second World War,War I and disorganization ofof the services ensued. Nature thus gave free rein to spontaneousspontaneous competition, whichwhich hashas seldom been favourable to introduced species, except for the more pioneer varietiesvarieties such as OkoumeOkoumé or Ter.minaliaTerminalia spp_/spp., which were able toto freefree themselvesthemselves fromfrom undergrowthundergrowth thanksthanks to strong initialinitial growth.growth.

The Taungya method couldcould according bebe thought thethe most effective,effectiv e, sincesince practically totalt o tal clearingclearing andand permanentpermanent andand totaltotal tendingstendings areare necessary forfor the survival of associated cultures. But this method, which African farmers have always foundfound limiting,limiting, hashas notnot beenbeen developeddeveloped asas widelywidely asas hoped.hoped. ItIt hashas been used mainly in openopen fforestso rests and for various reasons: accessibilty, facility ofof clearing andand,, most important, lack of available farmland. This method hashas createdcreated somesome good stands of Teak, Gmelina and other species in C6teCote d'Ivoire, Nigeria,Nigeria, etc.etc .

Extensive methods enabled large areas to be treated annually. In the end, however, tendingtending operations became so great as to be incompatible with the resources available. OnOn thethe otherother hand,hand, thethe enrichment methodmethod isis based on the determination to maintain aa heterogenousheterogenous standstand structurestructure byby conservingconserving part of the natural forest. The management of multispecies stands establishedestablished this way is highly complexcomplex andand difficult.difficult.

This isis whywhy enrichmentenrichment techniquestechniques havehave evolvedevolved towardstowards conversionconversion plantations permanently established on totallytotally cleared land. Natural heterogenous forest isis thusthus replacedreplaced byby high-yield,high-yield, monospecificmonospecific even-agedeven-aged stands.

The main resultresult ofof thesethese experiments isis that they have made clear what factors limit thethe techniques:techniques:

- costs of technical, human and financial resources that are incompatible with extensiveextensive treatmenttreatment ofof largelarge areas;areas;

lengthy follow-upfollow-up and workswo rks needingneeding long-term supervisionsupervision andand repeated intervention;intervention;

- economic and demographic developmentdevelopment ofof tropicaltropical African countries, which makes itit difficultdifficult toto reservereserve largelarge tractstracts ofof landland forfor low-low­ yield uses. ForestsForests are subjectedsubjected to intenseintense clearing by a ruralrural population thatthat isis growinggrowing exponentially.exponentially.

In thisthis connection,connection, it should be noted that due toto clearingclearing forfor agricuagriculturall tural use,use, a large part ofo f thethe olderolder plantationsplantations vanishedvanished beforebefore reaching loggingl ogging age.age. - 19 --

CHAPTER IIII

RECENT TECHNIQUESTECHNIQUES ANDAND ORIENTATIONS:ORIENTATIONS: REFORESTATIONREFORESTATION ININ CLEAREDCLEARED AREASAREAS

The technicaltechnical andand economiceconomic difficultiesdifficulties evidencedevidenced inin allall enrichmentenrichment operations havehave ledled forestersforesters toto preferprefer totaltotal replacement.replacement.

Considerations regardingregarding thethe evolutionevolution ofof thethe needneed forfor rawraw materialmaterial (timber asas wellwell as lumber and fuelwood)fuelwQod) inducedinduced officialsofficials toto intensifyintensify thethe rere-establishment- establishrnent oror creationcreation ofof usefuluseful resources.resources. TheThe objectiveobjective isis now toto seek optimal economic returnreturn perper unitunit ofof area, hence toto concentrate investments inin time and space.space.

The methodmethod selectedselected inevitablyinevitably impliedimplied totaltotal eliminationelimination ofof pre-pre­ existing formations by mechanizedmechanized clearing,clearing, followedfollowed by moremore oror lessless closeclose planting, which also permitted further use of machinerymachinery for tending operationsoperations.. This techniquetechnique hashas thethe advantageadvantage ofof beingbeing applicableapplicable toto anyany site,site, through a carefulcareful choicechoice ofof terrainterrain andand species.species.

The extensionextension ofof these new,new, usually monospecific,monospecific, ecosystemsecosystems hashas advanced with thethe modernizationmodernization ofof mechanicalmechanical equipment,equipment, and alsoalso withwith demographic pressurepressure on naturalnatural forests. The greatergreater needneed ofof farmland ~cceleratesaccelerates the disappearance ofof natural forests by considerablyconsiderably shortening fallow periods between plantings on thethe same site. The competition for land implies the limitation of wood-producing areas,areas, together withwith aa necessary intensification of artificialartificial regeneration.regeneration.

In WestWest Africa,Africa, CoteCate d'Ivoire is one ofof thethe countriescountries whichwhich hashas suffered the most from degradation of its forest resourcesresources by impoverishmentimpoverishment and disappearance.disappearance. In 1986,1986, it was said that 300300 toto 400400 000000 hectareshectares ofof productive forest were being destroyeddestroyed everyevery year. Reforestation actions in this countrycountry thus started quite early. The first plantationsplantations on areas that had been clearedcleared mechanicallymechanically began inin 1965. Total bulldozerbulldozer clearingclearing withwith windrowing ofof thethe remainsremains waswas adoptedadopted forfor TeakTeak inin 19681968 andand forfor otherother speciesspecies (Framire,(Framir6, Frake,Fraké, Samba,Samba, etc.) in 1977. This experience hashas made itit possiblepossible to develop techniquestechniques forfor preparingpreparing bothboth soilsoil andand seedlings.seedlings. Large-scaleLarge-scale actions have been undertaken inin otherother countriescountries asas well,well, includingincluding Nigeria,Nigeria, Gabon and Congo.Congo .

TheThe purpose of thisthis chapterchapter isis toto brieflybriefly reviewreview thethe principlesprinciples underlyingunderlying the most widely-used techniquestechniques of industrialindustrial reforestation.reforestation. MoreMore specialized studies and works, for instanceinstance liThe"The Forester'sForester's Handbook,Handbook," 11 provideprovide details, specifications and techniquestechniques forfor allall the phasesphases involved inin establishing aa stand.stand.

11 - FORESTRYFORESTRY TECHNIQUES

The principalprincipal factor to mastermaster when plantingplanting inin a moistmoist forestforest environment isis light. However, thisthis isis nono problem ifif itit isis decided to install a light-demanding species on a terrainterrain whose original vegetation has been completelycompletely removed. NATURAL FOREST INVENTORIES

FINANCIAL STUDIES Socio-Socio-Economic Economic Studies

Definition of Management Series

NATURAL FOREST IMPROVEMENT PLANTATIONS

'"o SILVICULSILVICULTURALTURAL STUDIES SILVICULTURAL STUDIES - Flora range - Topographic - VulnerabilityVulnerability - Pedologic - RegenerationRegeneration - Hydromorphic

Ilr TECHNICAL OPTIONSOPTIONS \ ENRICHMENT / 1110. • PROTECTION PRODUCTION ~ ~ Extensive reforestation / \ Manual intensive reforestation Mechanical intensive reforestation ll' ..iv UNEVEN-AGE MULTISPECIES STANDS CONVERSION INTO EVEN-AGE SINGLE-SPECIES STANDS -- 21 --

1.1 - Choice of sitessites

Theoretically, thethe sitesite chosenchosen forfor reforestationreforestation shouldshould bebe inin perfectperfect harmony with thethe requirements ofof thethe speciesspecies that isis to be transplanted. InIn actual fact, however, this choicechoice is basedbased onon manymany kindskinds of criteria: technical, legal,legal, socio-culturalsocia-cultural andand political.political.

All decisionsdecisions areare basedbased onon thethe physicalphysical conditionsconditions (relief,(relief, soils,soils, rainfall, etc.), which will be reviewedreviewed inin detail below when we examine thethe principal speciesspecies reservedreserved forfor timbertimber plantations.plantations. However,However, financial,financial, socialsocial and political problems areare often associated withwith these background conditions, and sometimes eveneven overrideoverride them.them .

In the case of mechanized industrial reforestation,reforestation, therethere isis nono doubtdoubt that an extensive area (several(several hundred hectares atat least)least) isis required for the investment toto bebe profitable. ToTo avoidavoid thethe disappointmentsdisappointments ofof thethe past,past, itit isis necessary, in thisthis case,case, toto plantplant moremore thanthan oneone species.species. EachEach sectionsection ofof homogeneous groundground mustmust havehave anan appropriateappropriate newnew "guest""guest" assignedassigned toto it.it.

When preparingpreparing aa reforestation planplan for mediummedium oror long-rotationlong-rotation species, the first step is to list allall constraconstraints.ints. TheThe policypolicy decisionsdecisions which initiate suchsuch projects must nevertheless aimaim at a properproper matchmatch betweenbetween speciesspecies and environment, knowingknowing thatthat thethe periodperiod ofof occupationoccupation willwill bebe longlong andand thatthat competition for landland remainsremains strong.strong.

From a more technicaltechnical pointpoint ofof view,view, itit isis importantimportant toto recallrecall thatthat before undertaking anyany reforestationreforestation project,project, plannersplanners mustmust trytry toto assessassess thethe environment inin whichwhich thethe futurefuture standstand isis toto grow,grow, andand aimaim toto preserve oror eveneven improve site characteristics.characteristics.

1.1.11 . 1.1 -- Appropriate sitessites forfor commercialcommercial reforestationreforestation

The decisiondecision toto assignassign aa givengiven sitesite forfor intensiveintensive reforestationreforestation operations takestakes severalseveral differentdifferent parametersparameters intointo considerationconsideration (DUPUY, 1987)1987): :

- The wealth of thethe natural formations.formations. IfIf there are natural forests sufficiently rich inin valuable species, the possibility of managing them should bebe consideredconsidered first.first.

- The vulnerability ofof thethe area.area. InIn ecologically fragilefragile areas,areas, itit isis necessary to avoid heavyheavy interventionintervention and givegive preferencepreference to managing natural formations or to non-mechanized methods of reforestation.reforestation .

- Sites to bebe reforestedreforested must be easilyeasily accessibleaccessible so thatthat timelytimely intervention and timbertimber removalremoval areare possiblepossible inin anyany season.season.

- The soil must be fertile enough to allow stands to develop harmoniouslyharmoniously.. - 22 --

SITE CHARACTERISTICS ALLOCATION

- Rich pre-existing Management of natural standsstands forest stand - VulnerableVulnerable or not vulnerable - Poor fertility

- Poor pre-existing Commercial reforestation forest stand IntensiveIntensive manual methods - VulnerabVulnerablele butbut accessible - Medium toto good fertilityfertility

- Poor pre-existingpre- existing Commercial reforestationreforestation forest stand Intensive mechanized methodsmethods - NotNot vulnerable and accessible - MediumMedium to good fertility

- Poor pre-existing Management, possible with forest stand protective reforestation - Vulnerable using extensive methods - Poor fertility - Poor accessibility

1.1.2 - Criteria for choosing intensive-reforestation sites

* The climatic, topographic and edaphic features of sites chosenchosen for reforestation must be suchsuch asas toto encourageencourage satisfactory tree growth. Little or nono investment shouldshould be put into sites where some factors wouldwould limit stand growth.

* Accessibility of thethe planted areaarea isis aa parameterparameter thatthat cannotcannot bebe

overlooked, forfor itit isis importantimportant onlyonly inin reforestationreforestation perper se,se l butbut alsoalso inin thethe follow-up (tending,(tending, thinning, wildfire protection, etcetc.). ) and in takingtaking outout harvested products.

SitesSites which are difficult tot o reach (steep(steep slopes, swampy areas, etc.) rrequireequire preparatory worksworks of considerable entityentity or difficulty which are oftenoften incompatible with productionproduction targets.targets.

* Suitable edaphic conditions are necessary for successful plantations. SurfaceSurface soilssoils thatthat are unevenly textured and chemicachemicallylly poor mustmust be avoided. TheThe samesame isis truetrue forfor hydromorphichydromorphic soils.soils.

Intensive mechanized reforestationreforestation mustmust bebe reservedreserved mainlymainly forfor areasareas with gentle slope and favourable soil (depth,(depth, physical characteristics, water balance, etc.), wherewhere therethere nono longerlonger existexist naturalnatural formationsformations whichwhich wouldwould justify management plans.plans. - 23 -

* It is obviouslyobviously better toto concentrateconcentrate investments onon the most fertile sites. Since establishmentestablishment costscosts are high, the goal must be maximum return on investment.investment. A good compromisecompromise between material production and the product'sproductls economiceconomic valuevalue mustmust bebe sought.sought. AA fertilefertile sitesite allowsallows higherhigher short-short­ term yield andand improvedimproved stock.stock.

Once thethe reforestationreforestation sitesite has been identified,identified, the next stepstep isis toto summarily assess thethe differentdifferent areasareas withinwithin it.it. The factfact thatthat mechanizedmechanized clearing is now widespreadwidespread mustmust notnot obscureobscure thethe factfact thatthat thisthis methodmethod mustmust sometimes be adapted toto actualactual sitesite conditions.conditions.

The basic parameters toto considerconsider are:are:

- slope - soil depth - soil texture.texture.

slope

It is difficult toto establishestablish a precise thresholdthreshold above which erosion becomes a considerableconsider~ble risk,risk, sincesince thisthis dependsdepends onon many parameters (rainfall,(rainfall, soil, slope length, etc.). When thethe inclineincline isis overover 15I S percent,percent, mechanizedmechanized clearing must be ruledruled out.out.

Generally speaking, wherewhere thethe ground is not flatflat andand clearingclearing isis mechanized, windrows mustmust bebe orientedoriented perpendicularly to thethe slopeslope toto limitlimit erosion.

Useful soilsoil depth

If treestrees areare toto growgrow harmoniously,harmoniously, the soil must be deep enoughenough toto allow thethe developmentdevelopment ofof aa balancedbalanced rootroot system.system.

Soils are seldom homogeneoushomogeneous along the length of a slope; in particular, itit isis easyeasy toto encounter:encounter:

- shallow soils characterizedcharacterized byby thethe existenceexistence ofof hardenedhardened upperupper horizons (hard(hard pan,pan, laterite);latente);

- very gravelly, percolatingpercolating soilssoils onon moundsmounds andand plateaux;plateaux;

- hydromorphic soils withwith anan asphyxiatingasphyxiating layerlayer presentpresent forfor severalseveral months of the year at less than 50SO cm from the surface in depressions and areasareas subjectsubject toto flooding.flooding.

These ratherrather unfertileunfertile soilssoils areare easyeasy toto identify,identify, and areare oftenoften connected with a particular topographic position.position . If intervention is indispensable, foresters must fitfit theirtheir sitesite preparationpreparation andand reforestationreforestation techniques toto thesethese conditionsconditions by:by,

- subsoiling soils with hardenedhardened horizonshorizons - draining of wetwet areas,areas, etc.etc.

It mustmust bebe remembered,remembered, however, that these methods are costly and must be usedused sparingly.sparingly. -- 24 --

The existence ofof aa gravellygravelly horizonhorizon maymay affectaffect soilsoil fertility.fertility.

The presence of coarse particles influences the physical characteristcharacteristicsi cs ofof thethe soil,soil, particularlyparticularly byby increasingincreasing itsits macroporosity.macroporosity.

The followingfollowing parametersparameters mustmust bebe considered:considered :

- the percentage of coarsecoarse particles - the thickness of thethe gravelly horizonhorizon - the layl ay ofof thethe gravellygravelly horizon.horizon.

If the proportion ofof coarsecoarse particlesparticles isis greatergreater thanthan 30-4030-40 percent,percent, it is importantimportant to take the depth of the gravellygravelly horhorizoni zon into account.account . IfIf itit exceeds 30-4030-40 cm,em, with thethe proportion of coarse elements over 50 percent,percent, soisoill fertility is very low.low.

The negative influenceinfluence of a gravelly horizonhori zon is mitigated if it líeslies beneath other horizonshorizons thatthat havehave nono coarsecoarse particles, areare balanced inin texturetexture and are at least 40-5040-50 cmcm deep.deep.

Soil texturetexture

Sandy and clayeyclayey soilssoils areare particularlyparticularly vulnerablevulnerable becausebecause ofof theirtheir uneven texture.texture.

- Sandy soils are very permeable; often they are heavilyheavily leached and lack organic andand mineral matter.matter . TheirTheir capacitycapacity forfor waterwater retentionretention is low. The surface horizon, which contains very little humus, must not be scrapedscraped forfor anyany reasonreason whatsoeverwhatsoever whenwhen reforesting.reforesting.

- Clayey soilssoils areare oftenoften asphyxiatingasphyxiating andand easilyeasil y compacted.compacted. It isis inadvisable to extractextract stumpsstumps fromfrom thesethese soilssoils mechanically,mechanically, or allow the frequentfrequent transittransit ofof equipment.equipment.

These parameters should not be considered separately, since they can offset eacheach other.other . The presence ofof coarsecoarse particlesparticles in clayeyclayey horizonshorizons improves their permeability. A clayeyclayey horizonhorizon lyinglying betweenbetween sandysandy horizonshorizons slows down water percolation.percolation. The presence of aa water-bearingwater-bearing stratum atat medium depth maymay bebe favourablefavourable onon sandysandy soilsoil butbut unfavourableunfavourable onon clay.clay .

Soil fertility

This depends onon all of the precedingpreceding factors pplusl us chemical composition, which is itself directly relatedrelated toto the bedrock. Certain limiting factorsfactors may appear at this level,level, suchsuch asas pH,pH, salinity,salinity, presencepresence ofof limestone,limestone, etc.,etc., andand accordingly conditioncondition thethe choicechoice ofof speciesspecies forfor planting.planting .

Before undertaking anyany reforestationreforestation project, itit isis necessary toto tryt ry to assess thethe growthgrowth environmentenvironment ofof thethe futurefuture reforestationreforestation and aimaim tot o preserve and eveneven improveimprove sitesite characteristics.characteristics.

Satisfactory treetree growth depends on the harmonious development of root and aerial systemssystems.. The root system has to provide the tree with sufficient water and minerals, asas wellwell asas stability.stabi lity. ToTo dodo so,so, itit mustmust bebe ableable toto reachreach at least one metremetre down.down. OPTION CRITERIA IN A REFORESTATIONREFORESTATION SERIESSERIES

Low gradient No Yes -I No Yes Hydromorphic or floodablefloodable Yes area

No Yes NoII Yes DeepDeep soil i (carapace,(carapace, slab) (7)o '" OJ '" 5' .l'l NoII Yes CD

Satisfactory physical No Yes C> ~ characteristics '0 (texture, coarse constituents) .0 '"::J Cf)

No Yes Satisfactory chemical No Yes C> characteristics c: I : ~ t Protection ManualManual Manual Q) Manual intensive intensive l.LU_ intensive

I MechanicalMechanical intensive I - 26 --

The existenceexistence of factorsfactors whichwhich couldcould limitlimit thethe growthgrowth ofof thethe rootroot system must be carefullycarefully takentaken intointo account;account; their neglect may resultresult inin failure. In some cases, commercial reforestation may be unfeasible; protection may bebe muchmuch moremore advisable.advisable .

An adequateadequate lightlight regimeregime fostersfosters properproper developmentdevelopment of the aerialaeri al system.

1.2 - NurseriesNurseries

The production of plant materialmaterial is oneone ofof the fundamentalfundamental stepssteps influencing futurefuture yield. ChoicesChoices areare mademade at the levels of genetic potential and of seedling husbandry technique.technique.

The material must be perfectly adaptedadapted tot o productionproduction targets:targets: volume, size, shape, etc. Generally speaking, experiments have made it possible toto select the bestbest species and provenancesprovenances.. Nevertheless, therethere isis still need for progress inin thethe fieldfield ofof genetic improvement;improvement; as we shall see,see, this appears clearly from the current orientationorientation ofof research.research.

The choice ofof propagationpropagation andand husbandryhusbandry methodsmethods meetsmeets certaincertain well-well­ known technical criteria. We shallshall not gogo intointo detailsdetails inin thisthis document;document i readers are referred to specific reports and educational texts.texts . However, some of the broad principles willwill bebe mentioned.mentioned.

The propagation ofof plantp lant materialmaterial isis basedbased onon twotwo methods:methods:

- the traditional sexualsexual route:route: seedsseeds

- the vegetative route:route: cuttings.c uttings.

1.2.11.2.1 - Plants produced fromfrom seeds

The firstfirst difficultiesdifficulties encounteredencountered by aa saplingsapling transplantedtransplanted forfor reforestation are:are:

- getting throughthrough transplanttransplant shockshock byby adjusting itsits root system to the new substratesubstrate asas quicklyquickly asas possible,possible,

- fighting competition fromfrom adventitiousadventitious vegetationvegetation andand regrowth,regrowth, particularly severesevere inin closedclosed forestforest areas.areas.

To dealdeal with competition,competition, the ideal is to transplanttransplant fair-sizedfair-sized seedlings with their root systems intact,intact, so that vegetation can recommence rapidly.

Accordingly, twotwo kindskinds ofof seedlingsseedlings maymay bebe prepared:prepared :

- bare-rooted

- ball-rooted. - 27 --

* Bare-rootedBare- rooted seedlingsseedlings

This method of preparation has been and still is the mostmost widelywidely usedused ini n the areas examined inin thisthis document.document.

Bare-rooted seedlings may bebe preparedprepared in differentdifferent waysways before planting:

- Full stem.stem. TransplantedTransplanted when 22 metresmetres tall.tall. AllAll leavesleaves exceptexcept forfor the terminal cluster are eliminated. RootsRoots areare shortened to justjust 10-20 cm.em.

- Tall stump or half stem. Unlike the full stem, all unlignifiedunlignified parts are eliminated.

Short stump.stump . TheThe stemstem isis cutcut downdown toto 7-107-10 cm.em . TheThe taproottaproot isis leftleft about 1010 cmem long.long.

* Seedlings with substratesubstrate leftleft aroundaround theirtheir rootsroots

variousVarious containers and supports have been tested over the course of reforestation history.history.

Polyethylene bags are thethe typetype mostmost widelywidely usedused today.today. Inexpensive,Inexpensive, easy to store and handle, theythey comecome inin different sizessizes andand cancan be used forfor all species. However, sincesince rootsroots cannotcannot pass through them, the seedling'sseedling's growing period and,and, accordingly,accordingly, itsits sizesize mustmust bebe limitedlimited toto avoidavoid deformation.deformation .

* Plant protection precautionsprecautions

Environmental conditionsconditions inin closedclosed forestforest areasareas often force nurserymen to deal with plant protection problems which must be solved quickly to avoidavoid jeopardizing the year'syear's production.production .

Preventive treatmenttreatment maymay bebe appliedapplied toto limitlimit risks.risks.

For speciesspecies sownsown inin boxesboxes andand sensitivesensitive toto damping-off,damping-off, it highlyhighly recommended to disinfect thethe soilsoil beforehand,beforehand, byby either:either:

- sprinkling itit withwith FormolFormal (0.1 1/m2).1/m2). TreatedTreated soilssoils mustmust be kept covered for twotwo weeks,weeks, thenthen leftleft openopen toto thethe airair forfor anotheranother twotwo weeks: the minimum time span between treatment and seeding isis thusthus four weeks;

- methyl bromide treatmenttreatment (gas(gas injectioninjection underunder cover).cover). InIn thisthis case,case, the seeds are sown two weeks later.later . InIn viewview ofof thethe toxicitytoxicity ofof thisthis substance, precautions mustmust be takentaken inin applyingapplying it.it .

Curative treatmentstreatments maymay alsoalso bebe necessary:necessary :

- To control fungi, essentially inin seedboxes, sprayingspraying with Benlate or Viricuivre (1 g/lOg/10 litres of water) is very effective.

- To control insectsinsects thatthat attackattack plantplant collarscollars and/orand/or rootsroots (,(termites, crickets, grasshoppers, etc.), the recommended treatments are - 28 --

spraying with Dieldrin (in(in 22% solution) and the use of poisoned baitbait (Dieldrin 2962% mixedmixed with meal).2meal) .'

- To controlcontrol defoliatingdefoliating insectsinsects (caterpillars, coleoptera)coleoptera), I spray 3 with 0.3%0.3% Decis.2Decis . ForFor suckingsucking insectsinsects (plant lice,lice, scale, etc.),etc.) I spray with malathion or vamidothion;vamidothion; forf o r drillingdrilling insects,insects, apply methydathion.

- To control molluscsmolluscs (snails,(snails, slugs, etcetc.),. ), place methaldehyde-basedmethaldehyde-based substances on theirtheir paths.paths .

- To control rodents (rats,(rats l etc.), place Coumarin-based bait on theirtheir paths. But rodents very often avoid ground fromfrom which the rass cover has been completelycompletely removed.removed .

* Lastly, there is the rare possibility of sowing the seeds directly in the planting area. This techniquetechnique requires soil preparation suchsuch asas to permit fastfast germinationgermination andand minimalminimal regrowthregrowth competition.competition. MostMost important,important, itit involves intense and repeatedrepeated earlyearly forestryforestry workwork (cleanings, tendings, thinnings) to achieve a standstand density compatible with yield objectives. The cost of these operations often cancelscancels outout anyany savings achieved atat thethe moment of planting.

1.2.2 - Plants produced fromfrom cuttingscuttings

Irregularity inin fruit-setting and/orand/or thethe existence of improved planting stock may direct reforestersreforesters towardtoward vegetativevegetative multiplication,multiplication, inin particularparticular large-scale planting of cuttings.cuttings .

To date, two methodsmethods of plantingplanting cuttings have been masteredmastered perfectly.

* Growing cuttings in framesframes

This techniquetechnique has beenbeen particularlyparticularly successfulsuccessful with SambaSamba treestrees (DELAUNAY, 1978).1978).

The framesframes (200(200 xx 9090 xx 6060 cm)em) areare coveredcovered withwith aa sheetsheet ofof plastic,plastic, which ensures aa greenhouse effect.effect.

The growth mediummedium isis aa 20-25-cm20-2S-cm deepdeep layerlayer ofof sandsand (diameter(diameter 11 toto 22 mm)mm) oorr sawdust. UnderneathUnderneath isis aa 25-cm25-cm layerlayer ofof pebbles (diameter(diameter 33 toto 4 cm) at the bottom ofof thethe frameframe toto ensure drainage.drainage. TheThe plantingplanting stock,stock, spacedspaced 80 80 xx 6060 cm,cm, is irrigated with 5-7 mm of water a day. One plant provides anan averageaverage ofof 5 cuttings/harvest, with 4 harvests aa year.year.

, Since DieldrinDieldrin isis no longerlonger manufactured,manufactured, and isis bannedbanned inin manymany countries, it has been replaced for control by Carbosulfanbased Suxon.Suxon. HCH,HcH, lindane and so forthforth areare usedused againstagainst grasshoppgrasshoppers.ers.

The namesnames ofof mostmost ofof the products mentioned here areare registeredregistered trademarkstrademarks.. Other substances with the same basicbasic activeactive principleprinciple may be used..used. ' -- 29 --

Cuttings areare herbaceous,herbaceous, 8-128-12 cmem long,long, withwith collarcollar diameterdiameter 66 toto 1212 mm.mm. Two or threethree leaves,leaves, halfhalf cutcut off,off, areare preserved.preserved. ToTo disinfectdisinfect thethe stockstock before planting inin thethe frames,frames, eacheach cuttingcutting isis dipped inin aa BenlateBenlate solutionsolution (0.05%), andand thethe basebase is then impregnated with a hormone solution (Exuberone,(Exuberone, etc.) which activates rhizogenesis.rhizogenesis .

The water inputinput isis 11 litrelitre/m'/day /m2/day forfor sawdustsawdust andand 4 litres/m'/daylitres/m2/day forfor .

The framesframes areare protectedprotected byby aa horizontalhorizontal andand verticalvertical shadingshading system.system. The cuttings are transplanted underunder shade when the root system is about 3 emcm long. They are gradually taperedtapered offoff andand hardenedhardened byby reducingreducing thethe shadingshading andand the frequencyfrequency ofof wateringwatering (once every two daysdays atat 7 or 8 weeks afterafter transplanting).transplanting) .

* Mist-grown cuttingscuttings

The principles ofof thisthis methodmethod ofof growinggrowing cuttingscuttings areare identicalidentical toto those described above,above, exceptexcept forfor thethe processprocess ofof waterwater distribution.distribution.

The growth medium isis coarsecoarse sandsand which isis misted continuouslycontinuously during the . Misting maymay bebe interruptedinterrupted duringduring thethe ,night, dependingdepending onon airair humidity. The cuttings are keptkept shadedshaded forfor a fewfew days,days, thenthen thethe shadesshades areare removremoved.ed . They are taperedtapered offoff and hardened by adding fertilizer to the mist (300 gramsgrams ofof fertilizer/10fertilizer/10 litres of water/lwater/1 000 cuttings), and temporarily restoring thethe shades.shades .

The hardening-off stagestage endsends 88 to 10 weeks afterafter thethe cuttingscuttings werewere harvested, and theythey maymay thenthen bebe transplantedtransplanted toto sackssacks oror beds.beds.

1.3 - Preparation of the site and planting

1.3.1 - Preparation ofof thethe sitesite

The goal isis toto completelycompletely freefree thethe groundground of itsits originaloriginal vegetationvegetation in orderorder toto facilitatefacilitate mechanizedmechanized operationsoperations andand givegive futurefuture transplantstransplants maximum light with minimumminimum competition.competition .

Reforestation isis generallygenerally carriedcarried outout inin degradeddegraded moistmoist evergreenevergreen oror semi-deciduous forestforest formations.formations.

In humid savannah areas, therethere isis lessless standing timbertimber thanthan inin closedclosed forest areas, and thethe workwork isis easier.easier.

Total deforestation isis thereforetherefore carriedcarried outout byby extractingextracting thethe stumpsstumps with crawler tractors (CATERPILLAR(CATERPILLAR D8-300D8-300 CVCV type)type) equippedequipped withwith treetree pushers or anchoranchor chains.chains. Merchantable logs have alreadyalready beenbeen hauledhauled out.out. The remaining stems,stems, stumps and detritusdetritus areare windrowed.windrowed . TheseThese operationsoperations areare carried out at thethe endend of thethe rainyrainy seasonseason thatthat precedes thethe planting year; this allows the detritus toto throughthrough aa dry season and the windrows will accordingly burnburn more easily. The windrows are set back toto leaveleave asas muchmuch ground as possible forfor planting.planting. Windrowingwindrowing is done withwith crawlercrawler tractorstractors (type 08D8 toto 06,D6, dependingdepending onon thethe vegetation),vegetation), usuallyusually equipped with rootrakes. Stumps that cannot be extracted may be levelledlevelled withwith aa tractor-mountedtractor-mounted cutting blade (Rome(Rome KGKG type).type). However,However, thisthis isis aa laboriouslaborious andand costlycostly operation.operation . - 30 --

Site prepared before planting

Grading andand ploughingploughing areare recommendedrecommended whenwhen possible.possible .

One of thethe drawbacks ofof thisthis method isis thatthat thethe soil is compacted by the frequent transittransit ofof heavy-dutyheavy-duty equipment.equipment. But eveneven more seriousserious isis thethe risk of removing thethe fertilefertile topsoil.topsoil. This work must therefore be conducted so as to avoid scrapingscraping thethe plantingplanting area.area .

Access trackstracks andand plotplot boundariesboundaries areare createdcreated atat thethe same time, inin the following approximate lengths:lengths:

For 100 hectares:hectares: 4 km of plot boundariesboundaries 2 km of main trackstracks 2 km of secondarysecondary trackstracks

Firebreaks are created in thethe ratioratio of 2 km every 100100 hectareshectares ofof plantation; they are approximately 100100 m wide and are accessible by unpaved roadsroads..

This isis thethe onlyonly methodmethod employedemployed todaytoday forfor industrialindustrial plantations,plantations, whether of timber, asas inin the CoteC8te d'Ivoire (Terminalia,(Terminalia, Samba,Samba, Teak,Teak, Gmelina),Gmelina) I fuelwood, as inin TogoTogo (Eucalyptus),(Eucalyptus), oror pulpwood,pulpwood, asas inin CongoCongo (Eucalyptus).(Eucalyptus).

However,However, wewe must distinguish betweenbetween plantationsplantations inin closedclosed forestforest areasareas

(Cote(C8te d'd'Ivoire, Ivoire, GabonGabon, I Cameroon, etc.)etc.) andand inin thethe humid savannahsavannah (Congo,(Congo, ,Togo, etc.)etc.). .

ThThee means employed to prepare the site and the relevarelevantnt costscosts areare muchmuch less significant inin thethe secondsecond case.case . - 31 -

1.3.21 . 3.2 -- PlantingPlanting

After thethe sitesite hashas beenbeen preparedprepared forfor planting,planting, sectionssections areare laidlaid outout for the future trees.trees. Conventionally,Conventionally, thisthis isis done by lininglining out successivesuccessive squares of 100 treestrees withwith compasscompass andand stakes;stakes; ifif necessary, stakes may also be set to mark exactlyexactly wherewhere thethe holesholes areare toto bebe dug.dug.

The holes areare dug with a hoe just a fewfew daysdays bebeforefore planting,planting, since the rain quickly fillsfills themthem upup again.again .

AsAS a pre-emergencepre-emergence treatment,treatment I the ground may be sprayedsprayed withwith aa herbicide beforebefore thethe rainyrainy seasonseason begins.begins.

Depending onon thethe naturenature ofof thethe transplants,transplants, theythey mustmust bebe handledhandled moremore or less delicately whenwhen transportedtransported fromfrom thethe nurserynursery toto thethe plantingplanting site.site. Special precautions must bebe takentaken withwith baggedbagged plants,plants, whosewhose well-protectedwell-protected root system must not suffer any shockshock beforebefore transplan~ation.transplantation. It is imperativeimperative to remove the plastic bagbag beforebefore planting,planting, andand tot o cutcut backback thethe lowerlower partpart ofof the root system soso thatthat itit will develop properly.properly . NoNo suchsuch problem arisesarises withwith biodegradable supports.supports.

Localized fertilizerfertilizer inputsinputs maymay alsoalso be advisable during transplant to optimize thethe saplings' initial growthgrowth.. However, in the absence of anyany generally-applicable researchresearch findings,findings, it wouldwould bebe prematurepremature to offer recommendations forfor industrialindustrial reforestationreforestation inin closedclosed forestforest areas.areas. PlantingPlanting density~ensity is an important silviculturalsilvicultural parameterparameter whichwhich variesvaries accordingaccording toto thethe species. ItIt isis thethe resultresult ofof aa compromisecompromise between:between:

- the silvicultural requirementsrequirements ofof eacheach speciesspecies planted;planted;

- economic constraints.constraints.

Planting density must bebe suchsuch asas toto createcreate aa standstand effecteffect where:where:

- the canopy closes up rapidly, inin order to limit the development of adventitious vegetation;vegetation;

the stand's training impact for individual trees (shape,(shape, pruning) is ensured.

There areare minimumminimum densitiesdensities whichwhich satisfysatisfy thesethese imperatives;imperatives i theythey depend on thethe architecturearchitecture ofof eacheach speciesspecies andand thethe wayway itit grows.grows.

These problems will bebe dealtdealt withwith inin greatergreater detaildetail whenwhen wewe examineexamine cultivation rules.rules.

Generally speaking,speaking, the methodmethod ofof large-scalelarge-scale mechanizedmechanized plantingplanting includes thethe followingfollowing steps:steps :

- Logging - 500 x 500 m plots are line-cutline-cut - Felling by bulldozer and timbertimber recoveryrecovery - Windrowing thethe remainsremains inin parallelparallel rowsrows 30-8030-80 mm apartapart - Burning windrowswindrows - Narrowing windrowswindrows - Grading thethe stripsstrips between thethe windrows, and plploughingo ughing if possible - Staking out - Planting - 32 --

It is particularlyparticularl y important that these operations be properlyproperly scheduled according toto thethe successionsuccession of dry and rainy . Poor timingtimi ng may cause delays thatthat oftenoften lastlast as long as a wholewhol e year and jeopardizejeopardize the results of thethe operationsoperations whichwhich havehave alreadyalready beenbeen completed.completed.

ASAs a practical example,example, thethe reforestationreforestation scheduleschedule for C8teCote d'Ivoire is shown onon thethe nextnext page.page.

2 - THE TECHNICALTECHNICAL-FINANCIAL- FINANCIAL EVALUATIONEVALUATION

Natural stand transformation techniquestechniques are directed at degradeddegraded forestforest stands, whose canopiescanopies areare oftenoften fullfull ofof gaps.gaps.

These standsstands areare felledfelled andand replanted.replanted. ClearingCl earing intensityintensity may varyvary according toto means andand objectives.objectives.

The solesale imperativeimperative isis toto completelycompletely suppresssuppress thethe overstorey.overstorey.

2.1 - The manual regrowthregrowth method

This is based onon thethe followingfollowing twotwo ideas:ideas:

- Total suppression ofof thethe overstoreyoverstorey byby devitalizationdevitalization oror felling.felling.

- Cutting back the undergrowth which isis to co-exist with the trees to be planted.

The succession ofof operationsoperations isis asas follows:follows:

Devitalization oror fellingfelling ofof treestrees whosewhose diameterdiameter isis overover 1515 cm.cm.

Manual coppicingcoppicing ofof thethe undergrowth.undergrowth.

- Planting.Planting .

- Tending (for(for 5-65-6 years).years) .

- Thinning.

Planting intervalsintervals correspondcorrespond toto aa densitydensity ofof 300-400300-400 stemsstems perper ha.ha .

2.2 - Association of reforestationreforestation andand agricultureagriculture (Taungya)(Taungya)

In certain cases,cases, particularlyparticularly inin populatedpopulated agriculturalagricultural areas,areas, thethe Taungya method maymay bebe applied.applied.

This techniquetechnique consistsconsists ofof introducingintroducing forestforest transplantstransplants on plotsplots where annualannual crops areare alsoalso grown,grown, atat firstfirst overover thethe wholewhole plot,plot, thenthen onlyonly between thethe lineslines ofof trees.trees . FarmersFarmers mustmust abandonabandon thethe landland definitivelydefinitively afterafter two years of consecutiveconsecutive cultivation.cultivation .

Originally,Originally, clearing and preparing the site were the farmer'sfarmers responsibility. - 3333 -

ANNUAL SCHEDULESCHEDULE OF WORKS FORFOR A COMMERCIALCOMMERCIAL REFORESTATION SSITEITE IINN COTE D'IVOIRE

.J F M A M .J .J A S o0 N D .,

Dry season for Lower C.I.C.1. CCI.-- - --M. 11111 '-aISMXIMIMIM Middle C.I.C.1. --cc, CM. - -- Pre-forest ---11=

PREPARATION OFOF SITESITE Strips Clearing -rowingWind-rowing Burning

Ground preparation (sub-soiling) Marking out

Pre-emergence treatmenttreatment

Planting --.1= --MIN IMP. - -- Compartmenting - Paths ---.frif beeM 1.10 ---OM. .12

NURSNURSERYERY Sowing Pricking-out

SILVSILVICULTURALICULTURAL OPERATIONSOPERATIONS Weeding (1 to 55 years)years)

Climber cuttingcutting (5 to 8 years)years)

Preselection Pruning Ise Thinning Haulage ofof thinning products - - 34 --

RATIOS PER HECTAREHECTARE OFOF PLANTATION (Prepa(Preparationration fforor the regrowth method)method)

Man-days 300 HP 80 HP CChainsawhainsaw crawlerc r awler tractor (days) (hours)(hours) (hours)

PREPARATION/PLANTING

Infrastructure 2.5 0.60 . 6 0.4

Line cuttingcutting 2.0 Climber cutting 5.0 Undergrowth preparation 25.0 4.04 .0

PoisonPoisoninging 6.0

NurseryNurser y 4.0 0.1 Planting 20.0

Firebreak 0.2 0.1 0.5

TOTAL 64.7 00.7. 7 0.50 . 5 4.54. 5

TENDING YearYear 0 to 88 52

TTOTALOTAL 116.7 00.7.7 00.5. 5 44.5.5

Today, as clearingclearing hashas becomebecome moremore andand moremore mechanized,mechanized, it is often carried out by reforesters themselves,themselves, and thethe "farmer's"farmer ' s forestryforestry role" isis reduced to tending thethe treetree plantationsplantations inin exchangeexchange forfor aa temporarytemporary grantgrant ofof llandand use.use.

The farmer/foresterfarmer/ forester associationassociation is successfully employed inin certaincertain iindustrialndustrial reforestation areasareas where, afterafter thethe treestrees have been planted, thethe land is temporarilytemporarily granted to farmersfarmers for oneone (or two)two) cycles of non-non­ permanepermanentnt food (or(or industrial)industrial ) crops.crops.

The goalgoal is to lighten thethe weightwe i ght of the item "tending youngyoung plantationsplantations"" by assigning itit toto thethe farmers.farmers . In exchange, they have the use of a growing area that has alreadyalready beenbeen completelycompletely cleared.c l eared.

Interplanted cropscrops are thus raisedraised duringduring thethe plantingplanting year,year, and sometimes the following yearyear asas well.well.

In pre-forest andand semi-deciduoussemi-deciduous moistmoist forestforest areas,areas, the followingfol l owing crops are suitablesui~ab le forfor association:association: - 35 35 -

- cocottontton

- groundnutsg r oundnu ts

- rain-fedrai n-fed

- maizemaize

- bananas

- sorghum,sorghum, etc.etc .

The area grantedgrant e d toto eacheach farmerf armer cannotcannot exceedexceed a fewfew hectares, ten at most.

2.3 - The mechanmechanizedi zed method

This methodmethod isis basedbased onon thethe followingfol lowi ng operations:operations:

- Mechanized clearingclearing withwith bulldozers.bulldozer s. - WinWindrowingdrowing thethe remainsremains with wi th bulldozers.bul ldozers . - GraGradingd ing (tractor).(tract or) . - Planting (manual).(manual) . - TendTendingi ng (manual(manual ++ mechanized).mechanized) . - Thinning (manual).(manual).

PPlantingl an t i ng intervalsinterval s vary from 2.52 . 5 x 2.5 2 . 5 m to 3.753.75 x 3.75 Tnm,, depedependingnding on the species.species.

RATRATIOSI OS PERPER HECTARE (Preparation wwithi th the mechanized method)method)

Man-days CrawCrawlerl er Tractor Chainsaw (hours) (hours) (days) 300 HP 140140 HPHP 120120 HP 80 HPHP 4545 HP

PREPARATION/PLANTING InInfrastructurefrastructure 2.5 0.60 . 6 0.4 Line cutting 2.0 FeFellinglling 0.4 33.5. 5 BBurningurning 00.5. 5 Windrowing 00.4. 4 1.8 2.2 1.0 SoilSoil ppreparationr eparation 00.2. 2 22.0. 0 0.8 NNurseryursery 22.5. 5 PPlantingl anti ng 4.0 0.10 . 1 FFirebreakirebreak 0.2 0.1 1.5 ------TTOTALOTAL 12.7 6.0 4.24 . 2 1.3 2.5 TENDTENDINGING Year 0 to 88 35 1.0 55.0. 0 TOTAL 47.7 66.0. 0 4.2 1.0 1.3 5.0 - 36 -

2.4 - Technical evaluationevaluation

Manual methods consist of thethe totaltotal eliminationelimination ofof small-diametersmall-diameter woodywoody growth, which isis cutcut andand burned.burned. OnlyOnly largelarge treestrees ofof nono commercialcommercial valuevalue remain, and these are poisoned (regrowth(regrowth method) or simply girdledgirdled (Taungya).(Taungya). After planting, therefore,therefore, aa certaincertain numbernumber ofof treestrees areare still standing; most are dead, butbut somesome survivesurvive devitalizationdevitalization treatments.treatments.

Branches and trunks gradually fall, causing damage to the population of young transplants. PlantedPlanted atat densitiesdensities ofof 300300 toto 400400 stems/ha,stems/ha, aboutabout 2/32/3 of the transplants survivesurvive afterafter 55 years.years.

If regrowthregrowth thrives,thrives, a woodywoody underunder storey,storey, shrubby atat first,first, then arborescent, forms again very quickly. These manual methods require considerable labour,labour I particularlyparticularly afterafter plantingplanting time;time; all tending operations are manual.

The need to intensify reforestationreforestation operationsoperations has led to the increasing mechanizationmechanization ofof manymany jobs.jobs.

When clearing involvesinvolves felling all pre-existing trees and windrowing the remains, tractors can circulatecirculate freelyfreely during planting and thinning, so these operations cancan bebe atat leastleast partlypartly mechanized.mechanized.

As to labour requirements,requirements, comparingcomparing thethe twotwo reforestationreforestation methods:methods:

- for sitesite'preparation, ·preparation, the ratio is 1 to 99 inin favourfavour ofof mechanizedmechanized methods;

- for planting, thethe ratioratio isis 1 toto 3,3, againagain inin favourfavour ofof mechanizedmechanized planting.

Unfortunately, thisthis kindkind ofof preparation impliesimplies the destruction of the humus horizon, particularly duringduring windrowing,windrowing, asas wellwell asas thethe explosionexplosion ofof aa very vigorous light-demandinglight-demanding regrowth.regrowth.

In practice,practice, manual and mechanizedmechanized tending requirements areare very burdensome duringduring thethe firstfirst sixsix years:years: itit isis necessarynecessary toto allowallow forfor 66 tractor-tractor­ hours/ha and 3535 man-days/haman-days/ha forfor mechanizedmechanized methods.methods. AtAt thethe samesame time,time, thethe anticipated growthgrowth gaingain isis aroundaround 3030 percentpercent inin favourfavour ofof mechanizedmechanized methods.methods.

In fact, the principalprincipal advantageadvantage ofof mechanizedmechanized methodsmethods is their reduction of labour requirements for site preparation and planting:planting; operations for which only a shortshort amount of time isis available. By the samesame token, mechanized methodsmethods makemake itit possiblepossible toto speedspeed thethe pace of reforestation.

On the other hand, as regardsregards costscosts per planted hectare, thethe ratioratio isis 1 to 2 in favour ofof manual methods. The possibilitypossibility ofof intensifying reforestation operations throughthrough mechanization must not obscure thethe problems created thereby:

The small size ofof thethe transplantedtransplanted saplingssaplings (bagged(bagged plants only aa few months old) means thatthat tendingtending operationsoperations must bebe carriedcarried outout with the greatest care.care.

Scraping of the humus layer is anan unfavourableunfavourable factor,factor, especiallyespecially in areas with fragilefragile soils.soils. - 37 --

The establishment of veryvery largelarge single species plantations weakens the ecosystem, particularly asas regardsregards plant protection; thethe recentrecent attacks of defoliatingdefoliating caterpillarscaterpillars on FrakéFrake plantations in CateCote d'lvoired'Ivoire areare anan example.example.

With several yearsyears ofof experienceexperience toto reflect upon, itit appears that this reforestation methodmethod mustmust bebe usedused withwith discretiondiscretion ifif itit isis toto remainremain valid.valid.

It is important toto taketake thethe followingfollowing considerationsconsiderations intointo account:account:

- On fragilefragile oror steeplysteeply slopingsloping soils,soils, it is pointless,pointless, or eveneven harmful, toto destroydestroy aa pre-existingpre-existing forest:forest: re-establishing aa forest stand by full reforestationreforestation onon mechanized tractstracts isis tootoo chancy.chancy.

It is alwaysalways advisable to manage such stands whenever possible. IfIf not,not I reforestation must bebe plannedplanned withwith thethe leastleast possiblepossible mechanization.mechanization.

- The creationcreation ofof veryvery largelarge singlesingle speciesspecies tractstracts mustmust bebe avoided.avoided. Foresters may use mixed stands of two species and at the same time create a mosaic of plots where the mixed unit becomes the monospecific plot.plot.

- The importanceimportance ofof tendingtending isis fundamental,fundamental, especially during thethe first fourfour years.years.

- It is essentialessential to keep to the thinningthinning schedule.schedule. AA delaydelay ofof severalseveral years may causecause aa 2020 toto 4040 percent loss inin yield and proportionally lengthen the rotation period. Once the stand is definitely established, itit must be rememberedr emembered that thethe ratio between planting density and definitivedefinitive density is aboutabout 11 to 10.10. If reforestersreforesters think theythey can thenthen restrest atat ease,ease, theythey hadhad betterbetter recallrecall all thethe operations stillstill toto come:corne: thinning,thinning, designationdesignation ofof finalfinal cropcrop trees,trees, pruning, andand soso forth.forth .

It mustmust bebe notednoted thatthat the manualmanual andand mechanizedmechanized methodsmethods alsoalso differdiffer as to planting density. InIn thethe mechanized method,method, thethe absenceabsence ofof anan arborescentarborescent lower storey with aa trainingtraining rolerole meansmeans thatthat plantingplanting densitiesdensities mustmust bebe higher, toto ensureensure thatthat thethe canopycanopy closescloses upup rapidly.rapidly.

By thethe samesame token,token, the firstfirst thinningthinning mustmust bebe effectedeffected earlier.earlier . Competition appearsappears earlierearlier onon aa mechanizedmechanized plotplot withwith 700700 stems/hastems/ha thanthan inin aa manually planted plotplot wherewhere 250-300250-300 stems/hastems/ ha survivesurvive aa few yearsyears afterafter planting. InIn thethe samesame way,way, onon aa mechanizedmechanized tracttract thethe standstand willwill havehave toto bebe thinned more often toto reducereduce itit toto thethe finalfinal density.density. -- 38 --

Each ofof thesethese methodsmethods hashas itsits advantagesadvantages andand disadvantages:disadvantages:

Method Advantages Disadvantages

Regrowth Minimum disruption of thethe Poisoned trees can fall environment.environment, on to the young transplants. Fast re-establishment of an arborescent lower storey with a The initial growth of thethe training role,role. transplants isis average.average.

Low planting cost.cost. Only limited areas can be Low material investments.investments. reforested each year, duedue to the amount of labour Later initial thinning, due to required. low planting density.density. Mechanization of tending operations isis impossible.impossible.

Taungya Forester/farmer association.association . Low Financial problems.problems. initial planting and tending Uncertain protection ofof costs. Minimum material saplings. investments.investments . Good initialinitial The method is limitedlimited toto transplant growth thanks toto small, often widely-widely­ farmersfarmers' tilling of thethe soil,soil . scattered areas.areas.

Mechanized Considerable mobilization of Considerable wood potential (timber/biomass).(timber/biomass) artificialization ofof thethe environment. Arborescent Disappearance ofof allall pre-pre­ lolowerwer storey absent,absent, existing vegetation,vegetation . replaced by aa lowlow grassgrass and shrub layer.layer. Mechanization ofof manymany jobs,jobs, hence much smallersmaller labourlabour Adventitious plants hard requirementsrequirements.. to control; repeated tendings necessary inin Good initialinitial growth ofof thethe young plantations. saplingssaplings.. Considerable materiamateriall Considerable areas can be investments. reforested eacheach year.year . High planting cost.cost .

Early thinning requiredrequired because planting densitydensity is higher,higher, to ensure the re-establishmentre-establishment ofof aa continuous arborescent cover.

Repeated thinnings.thinnings. - 39 -

2.5 - Financial assessment

One of the goalsgoals ofof reforestationreforestation is woodwood harvesting.harvesting. ThisThis obvioobviousus factfact should not obscure the numerous effects of the establishment of plantations in thethe environmentalenvironmental spheresphere (maintenance ofof the afforestationafforestation rate,rate, soil protection, water regulation, etc.),etc.) I the social sphere (job creation, forest/agriculture relationship, etc.), and the economiceconomic spheresphere (the(the wood,wood, self-sufficiency, etc.).etc.). ItIt isis alwaysalways difficultdifficult toto assessassess andand quantifyquantify thesethese macro-economic regionalregional parameters.parameters.

The standpoint adoptedadopted herehere isis that of the ownerowner ofof thethe forest,forest, whetherwhether a governmental entity,entity, aa privateprivate companycompany oror anan individual.individual .

Forests represent a financial investment,investment, so the properproper thing is toto trytry to estimate thethe profitability ofof anan investmentinvestment inin reforestation.reforestation.

Experience showsshows thatthat thethe mainmain factorsfactors affectingaffecting thethe costscosts andand benefits of a reforestationreforestation projectproject areare asas follows:follows:

- Land preparationpreparati on isis a veryvery largelarge cost factor in moist forest areas where standing growths toto be cleared represent a considerableconsiderable volumevolume of wood fromfrom unexploitable secondarysecondary species.species . This volume normally amounts toto 300 m3/ha. OnOn the other hand, the recovery of areas which have already been deforesteddeforested maymay generategenerate considerableconsiderable savings.savings.

Planting successsuccess depends primarily on carryingcarrying outout a rigorous tending programme. Little margin can be expected on this item. The problem lies in applying the working calendar, on which the future of thethe plantations depends.depends.

- The applicationapplication ofof aa correctlycorrectly scheduledscheduled thinningthinning planplan conditionsconditions optimum plantation growth. Any delay entails a growth loss and, by the same token, aa longerlonger rotationrotation cycle.cycle.

- The market price forfor wood isis certainly thethe most difficult parameter to estimate;estimate; in particular, it will depend on the quality of the wood and the size of the annualannual market (volume(volume ofof potential supply).supply) .

The internalinternal rate of returnreturn isis estimatedestimated byby consideringconsidering aa numbernumber ofof assumptions.

- concerning preparation costcost per hectare, which varies according to the natural woodedwooded state,state, plantingplanting method,method, etc.;etc.;

- on thethe lengthlength ofof thethe fellingfelling cycle,cycle, whichwhich dependsdepends onon fertility,fertility, compliance with aa correctcorrect thinningthinning calendar,calendar, etc.;etc.;

- on the market price perper cubiccubic metremetre ofof harvestedharvested wood.wood.

The following example involvesinvolves FrakéFrake plantationsplantations inin 35teCote d'Ivoire.drIvoire. - 40 --

For an average plantation cost of 450 000 F CFA/ha, corresponding to average conditions ofof industrialindustrial reforestation, the internal rate of return (IRR) variesvaries with the market price per cubiccubic metremetre asas follows:follows :

Felling cycle Price per cubic metre

25 years 30 years 33 years

4.54 % 10 000 F CFA 6.02 '"% 5.03 '"% 4.54 '" 15 000 F CFA 7.89 '"% 6.55 '"% 5.92 '"

7.65 % 6.92 20 000 F CFA 9.23 '"% 7.65 '" 6.92 %'" 25 000 F CFA 10.28 '"% 8.50 '"% 7.69 %'"

2.6 - OverallOverall assessment

A briefbrief examinationexamination ofof thethe technicaltechnical characteristicscharacteristics of manual and mmechanizedechanized reforestationrefo rest atio n methodsmethods showssho ws theirtheir respectiverespec tive limitationslimitations inin closed fforesto rest areas:

Manual method Mechanized method

Type of transplantt;±'ltnsplant Tall stem,stem, Bagged, 4 months old 1212-18- 18 months old

Density 300-400 stems/ha 700 stems/ha

Planting

Man-days 6565/ha/ ha 1313/ha/ ha Crawler tractor 0.70 . 7 hours/hahours/ ha 10.2 hours/ha

Tractor 0.5 hours/hahours/ ha 1.3 hours/hahours/ ha PPowero wer chainsachainsaww 4.5 hours/hahours/ ha 1.5 hours/hahours/ ha

Tending

Man-days 52/ha 48/ha Tractor 6 hourshours/ha/ ha

Thinnings 2 3

ReforestableReforestable area 200-400 ha/yrha/ yr 1 000-2 000 ha/yrha/ yr ((/concession)/ concession)

The main advantageadvantage of the manual method is its low cost, but it is highly labour-intensivelabour- intensive andand doesdoes notnot allowallow largelarge areasareas toto bebe workedworked eacheach year.year. - 41 --

The mechanized methodmethod allowsallows considerableconsiderable areasareas toto bebe reforestedreforested eacheach year, butbut requiresrequires substantialsubstantial investmentsinvestments andand earlyearly initialinitial thinning.thinning.

The considerable labour requirements rule out industrialindustrial reforestationreforestation projects byby manualmanual methods.methods. PlantingPlanting costcost isis onon thethe orderorder of 250 000 FF CFA/haCFA/ha plus supervisorysupervisory costscosts withwith manualmanual methods, and about 450 000000 F CFA/ha plus supervisory costs withwith mechanized methods.methods.

At thethe samesame time,time, the yieldyield fromfrom mechanizedmechanized plantationsplantations isis aroundaround 30 percent higher, thanksthanks toto thethe intensificationintensification ofof cultivationcultivation techniques.techniques.

As to the marketmarket priceprice of standing timber, a low estimate of 10 000000 FF CFA/m3CFA/m3 seemsseems reasonablereasonable forfor averageaverage gradegrade wood.wood. HigherHigher pricesprices maymay bebe obtained forfor betterbetter gradegrade wood.wood. The averageaverage priceprice ofof 15 000 F CFA/m'CFA/m3 (standing) is taken asas thethe workingworking standard.standard.

Under thesethese averageaverage conditions,conditions, thethe internalinternal raterate ofof returnreturn forfor well-well­ managed mechanizedmechanized plantationsplantations isis aboutabout 77 oror 88 percent.percent.

The I.R.R.I.R.R. ranges from 55 to 9.59.5 percent,percent, according to plantationplantation success andand growth.growth.

Where manual methods areare used,used, thethe I.R.R.I.R.R. will be slightly lower: from 4.5 to 8.5 percent, withwith anan averageaverage ofof 66 toto 77 percent.percent.

3 - PRINCIPLES FOR INTENSIVE REFORESTATION

The establishment of commercial timber plantationsplantations represents a considerable financialfinancial investmentinvestment whosewhose purposepurpose isis toto produce a givengiven categorycategory of wood productsproducts withwith anan optimumoptimum returnreturn onon thethe investment.investment.

The goal isis toto produce aa considerableconsiderable amountamount of high-grade timber in the shortest possiblepossible term.term.

3.13.~ -- Constraints forfor intensiveintensive reforestationreforestation

Numerous constraintsconstraints mustmust bebe takentaken intointo account.account.

1 - Site productivity is a determining factor in the raterate ofof returnreturn from forest investments.investments.

The study of sitesite potentialpotential isis aa necessarynecessary preliminarypreliminary step toto choosing an area for reforestation.reforestation . The choice mustmust be justified by thethe possibilities thethe sitesite offers forfor satisfactory growth. If the site is mediocre, the investment must be smaller. IfIf thethe site is good, the choice will be oriorientedented toward intensive silvicultural options.options .

2 - TheThe profitability ofof the investmentinvestment conditionsconditions the choicechoice ofof species to use inin reforestation.reforestation.

The logging age for a givengiven diameterdiameter must make it possible to achieve a satisfactory economiceconomic return. Slow-growing speciesspecies should be rejected inin favourfavour ofof thosethose withwith thethe shortestshortest possiblepossible rotation periods. - 42 --

3 - The goal isis toto produce aa considerable quantityquantity ofof timber.timber.

A compromisecompromise mustmust bebe soughtsought betweenbetween obtainingobtaining thethe significantsignificant individual sizes pertinent to a timbertimber targettarget andand maintainingma i ntaining sustained standstand production.production.

4 - The timber produced must bebe of good quality.quality.

The choice ofof species,species, provenancesprovenances andand silviculturalsilvicultural techniquestechniques should be aimed at eventually obtaining timber whose quality will justify thethe investment.investment.

5 - WoodWood resources must bebe easyeasy toto mobilize.mobilize.

Stand accessibility isis an importantimportant parameter. ItIt isis essential toto be able to reach the stands, carry out all the necessary forestry operations andand removeremove thethe productproduct easily.easily .

3.2 - Basic principles

The principles governinggoverning intensiveintensive reforestationreforestation areare asas follows:follows:

1 - The choice of the reforestation site must justify the investment.

Sites chosen for reforestation must have climatic,climatic, topographic and edaphiCedaphic characteristicscharacteristics thatthat willwill fosterfoster satisfactorysatisfactory treetree growth.growth. Sites where therethere existsexists aa factorfactor thatthat wouldwould limitlimit standstand growthgrowth deserve littlelittle oror nono investment.investment.

The parameter ofof accessibilityaccessibility isis significantsignificant notnot onlyonly asas regardsregards reforestation perper setse, but alsoalso for forestry carecare (tending, thinning, forest-fire protection, etc.) and mobilization of thethe output.

Sites that cannotcannot bebe reachedreached easilyeasily (steep slopes,slopes, low-lying areas, etc.) requirerequire considerableconsiderable oror difficultdifficult sitesite preparationpreparation work that isis often notnot very compatiblecompatible with aa productionproduction target.target.

Proper edaphicedaphic conditionsconditions areare essentialessential toto plantationplantation success.success . Surface soils thatthat areare unevenuneven inin texturetexture andand chemicallychemically poorpoor should be avoided. The same isis true for hydromorphic soils.soils.

Intensive mechanized reforestation shouldshould bebe used primarily on areas with gentlegentle slopes, favourable soils (depth, physical characteristics, water balance, etc.), and no natural formations that would callcall forfor managementmanagement instead.instead .

On sitessites atat riskrisk (for(for climate,climate, soil,soil, topography,topography, etc.), forestry intervention should be slightslight andand preferencepreference givengiven toto intensiveintensive and extensive manualmanual methodsmethods ofof reforestation.reforestation.

2 - SilviculturalSilvicultural rulesrules areare linkedlinked toto profitability.profitability.

A compromisecompromise must be soughtsought between the economic value of the reforestated area and its yield in volume per hectare.hectare . Producing maximum volumes impliesimplies high densities of small trees withwith youngeryounger - 43 --

logging age,age, greater establishmentestablishment costs andand lowerlower financialfinancial returns.returns .

The aimaim isis toto achieveachieve maximummaximum individualindividual growthgrowth whilewhile keepingkeeping standing stem densities lowlow enoughenough toto limitlimit competition.competition.

Planting intervals shouldshould be adapted to obtain well-shaped trees whose canopy will limit thethe development of adventitiousadventi tious vegetation.

Thinnings shouldshould bebe earlyearly andand vigorous,vigorous, inin orderorder toto encourageencourage initial growth and limitlimit thethe number ofof thesethese operations.operations.

A fertile sitesite willwill supportsupport aa higherhigher densitydensity ofof standingstanding stemsstems ofof a particular diameter thanthan aa lessless fertilefertile site.site.

3 - The expected forestryforestry investmentinvestment mustmust be geared toto thethe site.site.

itIt is preferablepreferable toto concentrateconcentrate investmentsinvestments onon thethe mostmost fertilefertile sites, particularly asas regards:regards:

- the introduction ofof high-performinghigh-performing selectedselected plantingplanting stock; - the choice of speciesspecies accordingaccording toto theirtheir merchantablemerchantable value;value; - pruning, fertilization,fertilization, andand soso forth.forth.

These last two itemsitems are still in thethe realmrealm ofof thethe future,future, butbut should allow appreciable quantitativequantitative andand qualitativequalitative gains.gains.

4 - The future of a treetree isis decideddecided duringduring itsits initialinitial years.years.

A tree'stree's qualityquality andand growthgrowth areare determineddetermined byby thethe applicationapplication ofof early and repeatedrepeated care:care:

- good-quality (origin,(origin, size,size, health, etc.) planting stock must bebe used;

- tending operations mustmust bebe carried out beforebefore thethe standstand isis attacked by adventitious vegetation;vegetationi

- the stand mustmust be thinned beforebefore tree growthgrowth slows down significantly, inin orderorder toto take maximum advantageadvantage ofof thethe initialinitial growthgrowth phase, when increasesincreases are most significant.significant.

5 -- SilviculturalSilvicultural factors areare interdependent.interdependent.

It is useless to try to improve the final yield by acting on justjust one factor and at the same time overlookingoverlooking eventual constraints.

The main factorsfactors are:are:

- sitesite - planting stock - tendingtending - thinningthinning

Each of thesethese factorsfactors mustmust bebe takentaken intointo equalequal considerationconsideration inin order to achieve a satisfactorysatisfactory endend result.result. - 44 --

G6 - The logging cyclecycle dependsdepends onon thethe site.site.

The more fertilefertile aa site,site, thethe more likelylikely itit isis toto produce aa largelarge quantity ofof woodwood inin thethe shortshort term.term.

To avoid lengtheninglengthening rotation cycles, logging diameter should be adapted toto sitesite fertility.ferti l ity.

Accordingly, the logging diameters chosen for a poor site should be smallersmaller thanthan forfor aa goodgood site.site.

RECOMMENDATIONS

Commercial reforestationreforestation isis anan investment.investment . PriorityPri ority isis givengiven toto sitessites that are accessible, not vulnerable, fertile, and containing naturalnatural formations thatthat cannotcannot bebe managed.managed.

The choice of reforestation method depends on the area's vulnerability.

The intensity of forestryforestry operations and logging age must be adapted to thethe degreedegree ofof fertility.fertility. PriorityPriority is givengiven toto investmentsinvestments (planting stock, fertilization, thinnings, etc.)etc . ) on fertile sites, where expected profit isis higher.higher.

SilviculturalSilviculturai factors are interdependent, andand nonenone ofof them should bebe neglected (site study, appropriate planting stock, tendings, thinnings, etc.).etc.).

The tree'stree ' s futurefuture dependsdepends on itsits initial years.years. Tending qualityquality strongly conditions the stand's potential value. Delays inin thinningthinning can never be mademade up.up.

From the economic standpoint, itit isis better to aim for aa standardstandard yieldyield rather thanthan aa maximummaximum yieldyield perper hectare.hectare.

Logging age dependsdepends onon thethe site'ssite! s fertility.fertility. AnAn excessivelyexcessively longlong rotation period on a mediocremediocre sitesite mustmust bebe avoided,avoided, bearingbearing inin mindmind that a commercialcommercial timbertimber targettarget requiresrequires a logginglogging diameterdiameter ofof atat least 4040 cm.cm.

Logging age must thus be a reasonablereasonable compromisecompromise betweenbetween technical and financial constraints.constraints.

7 - Logging diameter influencesinfluences thethe mobilizable volume of timber.timber.

The objective of producing commercialcommercial timbertimber allowsallows thethe logslogs toto bebe exploited up toto anan endend cuttingcutting pointpoint ofof aboutabout 2020 cm.cm.

Current exploitation rates of around 80 percent rule out logging diameters ofof lessless thanthan 4040 cm.cm. - 45 -

3.3 - Limits on the introductionintroduction of plantation speciesspecies

In establishingestablishing commercialcommercial timbertimber plantations,plantations, areasareas reforestedreforested forfor production forestsforests mustmust havehave thethe rightright soilsoil characteristics.characteristics.

In particular, plantations shouldshould notnot bebe establishedestablished onon thethe followingfollowing types of soils:soils:

- shallow soils underlain byby aa lateritelatente oror gravelgravel horizonhorizon lessless thanthan 60-80 cm deep;deep; the available soil depth must allow the root system to develop harmoniously;harmoniously;

- sandy-textured and fast-drainingfast-draining soilssoils (slopes and knobs)knobs ) which cannot ensure a sufficient waterwater supplysupply toto transplants,transplants, particularlyparticularly during very drydry years;years;

- very hydromorphichydromorphi c soilssoils thatthat tendtend toto asphyxiateasphyxiate plantplant roots;roots;

- highly water-retentivewater- retentive clayey soils; these must bebe ruled out altogether, particularly when the reforestation species is introduced at thethe limitslimits ofof itsits natural range.range.

Foresters may thenthen resortresort toto creatingcreating protectionprotection plantations,plantations, or plantations of constructionconstruction timber,timber, dependingdepending onon thethe particularparticular case.case.

For anyany givengiven area,area, the principal limiting edaphic factor to bebe consideredconsidered seems toto be thethe water balance. One of thethe mainmain causescauses ofof failurefailure in man made forestsforests isis thatthat thethe transplantstransplants dodo notnot receivereceive enoughenough water,water, especially at a youngyoung age,age, whenwhen thethe standstand isis beingbeing established.established.

On the other hand, oneone must be suresure toto introduceintroduce thethe various species only in areasareas that areare ecologicallyecologically appropriate. The following table shows the areas where the variousvarious species grow naturally,naturally, and thethe bioclimaticbioclimatic conditionsconditions required forfor commercialcommercial afforestation.afforestation. - 46 --

TABLE OF CLIMATE-VEGETATION RELATIONS (Cote(Cate d'd'Ivoire) Ivoire)

Regions Lower Middle Pre-forest SubSudanese

CoteCate d'd'Ivoire Ivoire CateCote d'Ivoired I Ivoire CoteCate d'Ivoired r Ivoire CoteCate d'Ivoire

Natural plantplant Moist Moist semi-semi- Guinea Wooded shrub formations evergreen deciduous savannah savannah forest forest Closed forest Dry forest

Climate 2 rainy 2 rainy 1 to 2 rainy 1 rainy seasons seasons seasons season 2 200

Commercial Niangon FrakéFrake Teak Gmelina reforestation OkoumeOkoumé FramiréFramire Gmelina species Badi Samba Pines Framir6Framire CedCedrelar ela Gmelina Teak Pines Gmelina Mahogany Pines

p : annual rainfall expressedexpressed inin mm/year

Dry month : month inin which total potential evapotranspiration (P.E.T.)(P.E.T.) isis higher thanthan cumulative monthly rainfallrainfall (R)(ELDIN(R) (ELDIN 1971).1971) .

Dry season : series of consecutive monthsmonths withwith aa water deficit:deficit : P.E.T.P.E.T. >> R.R. - 4747 -

NaturalNatural rangerange Commercial reforestation areaarea Species Rainfall Dry months Rainfall Dry monthsmonths Type of minimum maximum forest max.max. minmin.. min. max.

Teak*Teak" 44000 000 1 100 0 8 1 100 8 E to SGSG

FrakeFraké 1 800 1 300 4 6 14001 400 6 SDSD

FramireFramiré 22500 500 1 300 3 66 1 500 5 E to SDSO

Samba 22000 000 1 100 4 7 1 300 6 SDSD

CedrelaCedrela* .. 22500 500 1 200 2 6 1 400 6 E to SDSD

Gmelina* 44500 500 700 0 8 1 100 8 E to SGSG

Badi 33000 000 1 500 2 6 1 400 6'6 E to SDSO

Pines·Pines* 44200 200 700 0 6 10001 000 6 E to SGSG

Niangon 22200 200 1 800 2 4 1 800 4 E

Okourné*Okoume" 3 500 1 500 1 4 1 800 4 E

Sipo 22500 500 1 400 2 5 1 600 4 E to SDSD

Cordia"Cordia* 55000 000 1 000 0 55 1 600 4 E to SDSO

E : Evergreen; SDSO: : Semi-deciduous;Semi-deciduous; SGSG: : Sudano-Guinean Sudano-Guinean *•. : species introducedintroduced in CôteCote d'ivoired'Ivoire

Note that these areare averageaverage figuresfigures whichwhich mustmust inin no casecase obscureobscure thethe existence of cyclic climateclimate variationsvariations whichwhich may jeopardizejeopardize thethe successsuccess ofof reforestationreforestation.. Reforesters must thereforetherefore also considerconsider thethe relationshiprelationship between the distribution andand thethe intensityintensity ofof annualannual rainfall,rainfall, asas wellwell asas thethe maximum duration of drydry seasons;seasons i thesethese areare limitinglimiting climateclimate factorsfactors thatthat influenceinfluence the choice of species toto plant.

The minimum densities toto observe when transplantingtransplanting areare asas follows:follows:

Density Species

1 500 stems/ha Teak

1 100 stems/ha Niangon, Gmelina, Pines,Pines, Cedrela, Okoumé,Okoume, Badi

700 stems/ha Framire,Framiré, Fraké,Frake, Samba

When high plantingplanting densitiesdensities areare calledcalled for,for, reforesters are oftenoften tempted to reduce them in light of economic constraints (planting(planting cost) and technical constraints (minimum(minimum spacingspacing requiredrequired forfor mechanizedmechanized tending).tending) . - 48 -

RANGES OF SOME COTE D'IVOIRE SPECIES

Natural range of the niangon Natural rangerange ofof thethe frake"frake and the samba

Niangon ~C2~~;~~~:::2J

o0 100km100 km o0 100km100 km !

Natural rangerange of the mahoganiesmahoganies Natural rangerange ofof thethe framire"framire

Bastard M.

Broad-leaved M.

Bassam M.

100 km 0o 100 km

~ Range overlapsoverlaps o0 Range extensions Based on GuillaumetGuillaume! (Orstom)(Orstom ) - 49 -

In the case of species such as Teak, genetic improvement is directed toward selecting late-ramifyinglate-ramifying individualsindividuals oror provenancesprovenances (see(see forestryforestry data sheets). Consequently, thethe stand effect in young age is fundamentalfundamental toto allowallow the most favourable interactions influencing such parameters as the straightness ofof the futurefuture buttlogs.buttlogs . To avoidavoid reductionsreductions in the value ofof future stands,stands, it therefore seems important to trytry tot o adaptadapt reforestationreforestation techniques soso as toto allow for the silvicultural constraints inherent inin these high planting densities.densities.

3.4 -- General silviculturalsilvicultural rulesrules

3.4.1. - ClearClearingi ng

Reforestation afterafter totaltotal oror partial clearingclearing impliesimplies modificationmodification ofof certain biotic parameters:parameters:

- At soilsoil level,level, the sudden removal of all woody covercover changeschanges thethe terms of thethe waterwater balance.balance. RainwaterRainwater isis nono longerlonger interceptedintercepted byby the woodywoody cover;cover; evapotransiprationevapotransipration andand infiltrationinfiltration areare reduced,reduced, erosion providingp~oviding thethe incentiveincentive forfor locallocal erosion.erosion .

- Burning thethe debris instantly releasesreleases thethe storedstored mineral potential.potential . Leaching shortensshortens the span of timetime duringduring whichwhich thisthis inputinput cancan bebe used toto reconstitutereconstitute thethe stand.stand.

- The initial compositioncomposition of plant life is completely altered by the elimination ofof allall pre-existingpre-existing species.species.

- Sunlight at ground level surges from around 10 percentpercent toto 100100 percent. These newnew sitesite conditionsconditions correspondcorrespond toto thethe ecologicalecological niche of pioneer light-demandinglight-demanding species.species .

Due to thethe totaltotal destructiondestruction ofof thethe cover,cover, forestersforesters areare obligedobliged toto plant light-demanding reforestationreforestation speciesspecies thatthat can survive out in the openopen from the moment theythey areare planted.planted.

In addition, competition for the cleared space directs the forester's choice toward species withwith fastfast initialinitial growth.growth . TheseThese speciesspecies mustmust bebe able,able, with the help of growth-encouraging silvicultural operations, to free themselves as quickly as possible fromfrom the influence of the natural regrowth.

From the very moment thethe ground isis laid bare, it is rapidly invaded by light-demanding floraflora.. ThisThis naturalnatural flora competes directlydirectly forfor waterwater and light with the speciesspecies chosenchosen forfor reforestation.reforestation .

These competing speciesspecies maymay bebe divided intointo fivefive groups (MALLET, 1983) 1983):

- Shrubby dicotyledons,dicotyledons, suchsuch as:as:

* MusangaMUsanga cecropioides (Aga umbrellaumbrella tree) in moistmoist evergreenevergreen forest areas.

* Trema guineensis, Solanum torvum,torvum, Solanum verbascifoliumverba sci folium inin moistmoist semi-deciduous forestforest areas.areas . - 50 -

- Eupatorium odoratum, a subspontaneous plant which invades clearing very rapidly andand cancan formform aa continuouscontinuous layerlayer 1-1.501-1.50 mm highhigh inin aa fewfew months.

- Dicotyledonous creepers (Pueraria(Puerariaphaseolides, phaseolides~ CentrosemaCentrosemapubescens, pubescens, Ipomea spp., etc.), which use the planted saplings as supports and thus deform or even smothersmother themthem by overrunning themthem completely.completely.

- Tall monocotyledons (up(up toto 22 m) such asas RottboeliaRottboelia exaltata,exaitata, Panicum maximum, Sorghum spp.spp., , etcetc.,. , which can smother the young transplants.

- Medium-height monocotyledonsmonocotyledons (up to 11 m) such as DigitariaDigi taria spp.spp., J Brachyaria spp., Paspalum conjugatum,conjugatum, Eleusine indica,indica, Panicum laxum, etc., onon shallowshallow soils.soils.

After planting, thethe saplingssaplings areare very rapidly rivalled by these light­light- demanding adventitious plants.plants.

These adventitious plants possess considerable potential for colonization: the re-establishment ofof aa continuous layer of vegetation on totally bare ground takestakes nono moremore thanthan aa fewfew months.months. TheThe initialinitial growthgrowth raterate of a forest transplanttransplant isis slowslow inin comparisoncomparison (0.5(0.5 toto 22 m/year).m/year).

Without silvicultural intervention, the majority of the young transplants willwill bebe eliminatedeliminated byby adventitiousadventitious plants.plants.

Two methods are used toto controlcontrol adventitious vegetation:vegetation:

- the mechanical method,method,

- the chemical method.method.

3.4.1.13 . 4.1.1 -- Mechanical methodmethod

This method combines manual mowing and the destruction of vegetation by tractor-drawntractor-drawn equipment.equipment.

Between planting lines,lines, where there is room for a tractor to pass, a tractor-drawn roller-grinder or roto-grinderrota-grinder destroys woody and grassygrassy vegetation. ThisThis method mustmust bebe used only where slopes are very gentle (below(below 10 percent), andand onlyonly betweenbetween thethe lines.lines.

Depending on thethe amountamount ofof grassgrass covercover onon thethe plot,plot, the followingfollowing equipment isis used:used:

Roller-grinder withwith aa 1.501.50 m swath,swath, drawn by a 45 HP tractor, for lightly overgrownovergrown plotsplots (young plots 1 to 3 years old).o ld) . The machine can cleanclean roughlyroughly 1.5-21.5-2 hectareshectares perper hour.hour.

Roller-grinder, 2.5 m wide swath, drawn by a 120 HP tractor, for heavily overgrown plots with woody regrowthregrowth (plots(plots 3 toto 66 yearsyears old). The machine cancan cleanclean roughlyroughly 1.5-21.5-2 hectareshectares perper hour.hour. CHRONOLOGCHRONOLOGICALICAL SEQUENCESEQUENCE OFOF SILVICULTURALSILVICULTURAL OPERATIONS

0 OPERATION YEAR 0 1 2 3 4 5 6 7 --- 12-12 0 15 15 - ---- 30 - 40 -- --

1 1 o- Line 1 11 1 1 ChemicaChemicall 1 1 o- In1erlineInterline 1 1 1 1 tending o- Windrow 1 1 1 11 -- --

-o Line MechanicalMechanical o ... - InterlineInterline 1 3/5 2 1 1 -( 2")- tending 2 ( 2* ) 10- o- WWindrowindrow -- --

o- Line 1 3/5 2 2 1 1 Manual o- IInterlinenterline tentendingding o- Windrow 1 1 1 1 1 1 ....'" -- --

Climber cutting 1 _(( 2*2·)_ ) 111".~ -- ---

Selection of according to speciesspecies standing trees ----OEM i1,. Mf .. I I -- --- ccoccordingrding toto speciesspecies TThinninghinning ------~

I I ------ccordingccording toto speciesspecies PrunPruninging ... --- .. I

(2"):(2.): TwoTwo oror three three tending Icnding andand climberclimbe rcutting cutting operations operations between between thethe agesages ooff 7 andand 1515 yearsyea rs aass prelpreliminariesiminaries ttoo thinnthinninging andand/or/o r priningprining.. -- 52 --

Bladed roto-grinderroto- grinder powered by thethe tractortractor engineengine (120(120 HP),HP), forfor plots heavily invadedinvaded by woodywoody regrowth.regrowth. The machine cancan cleanclean roughly 0.5-1 hectares perper hour.hour.

Cleaning operations on thethe lineline itselfitself are performed byby handhand withwith aa bush knifeknife (2 man-daysman-days per gross hectare).hectare) .

The same holds for narrowingnarrowing windrows (2(2 man-days/gross hectare,hectare, oror 220220 m ofof windrows/man-days)windrows/man-days) .

The frequency of complete cleaning sweeps required for correct tending depends on thethe dynamicsdynamics ofof thethe adventitiousadventitious vegetation.vegetation. It rangesranges fromfrom 55 sweeps a yearyear (shrubby dicotyledons)dicotyledons) to 8 sweeps a yearyear ( Eupatorium odoratum). OneOne oror twotwo operationsoperations aa yearyear areare neededneeded toto narrownarrow windrows.windrows.

3.4.1.2 - Chemical method

The composition andand growth of adventitiousadventitious flora can bebe controlledcontrolled withwith herbicides. Two kindskinds ofof treatmenttreatment shouldshould bebe plannedplanned (MALLET,(MALLET, 1983):1983):

- Pre-emergence treatments beforebefore plantingplanting inin order toto retardretard thethe appearance of weeds and toto curbcurb theirtheir furtherfurther development.development.

- Adventitious vegetationvegetation controlcontrol treatmentstreatments afterafter planting retard the growth of such vegetation and/orand/ or modifymodify theirtheir composition.composition.

- Pre-emergence treatmentstreatments

- These are carried out at the end of the dry season or beginning of the rainy season, when the planting site has been cleared of all debris andand thethe weedsweeds areare notnot yetyet established.established.

- The recommended active substance is DIURON, at rates of 2.22 . 2 to 2.52 . 5 kg of A.S./ha.A.S./ha . ThisThis dosedose isis effectiveeffective onon adventitiousadventitious plants,plants, andand entails no phytotoxic risk through residues on the young transplantstransplants.. It is particularly effective against bushy dicotyledons.

The treatment is carried out with ramp sprayers drawndrawn byby a 80 HP tractor (1.8(1.8 toto 2.32 . 3 haha treatedtreated perper hour;hour; 0.2 to 0.3 man-days/ha).man-days/ ha). The tractor advances at 3.53.5 km/hourkm/hour andand sprayssprays thethe mixturemixture atat thethe rate of 240 litreslitres perper treatedtreated hectarehectare withwith liquidliquid pressurepressure ofof 1.51.5 kg/cm2.kg/em' .

- The ground can be planted one monthmonth afterafter treatment,treatment, thusthus postponingpostponing initial tending for about 6-7 months and obviating the need forfor two or three manual/mechanical tendingstendings duringduring thethe firstfirst year.year .

- Adventitious vegetationvegetation controlcontrol treatmentstreatments

For contact herbicides toto be most effective, the vegetation must be about 40 cm talltall priorprior toto treatment.treatment. InIn practice,practice, thethe herbicideherbicide isis applied about one month afterafter the weeds have been cutcut back memechanicallyc hanically oror manually.manually . - 53 -

- The activeactive substancessubstances recommendedrecommended forfor inter-line treatment areare M.S.M.A. (Monosodium methylmethyl arsenate) mixed with 2.4 D (2.4 dichlorophenoxyacetic acid) in the dose of 2.92.9 ++ 1.11.1 kgkg ofof activeactive substance/ha when the adventitious flora consists of both dicotyledons andand monocotyledons.monocotyledons.

- For dicotyledons,dicotyledons, especially Eupatorium,Eupatorium, the recommendedrecommended activeactive substances are PICHLORAME mixed with 2.4 D (0.13(0 . 13 + 0.480 . 48 to 0.26 to 0.960 . 96 kg A.S./ha), oror TRICHLOPYRTRICHLOPYR ++ 2.42.4 DD (0.2(0.2 ++ 0.860.86 kgkg A.S./ha).A.S./ha).

- For graminaceous flora,flora, thethe recommendedrecommended activeactive substancesubstance isis DALAPON (6.5 kg A.S./ha).A.S. / ha).

To treat windrows colonized byby shrubby dicotyledons and/orand/or Eupatorium,Eupatorium, the best results areare achievedachieved byby jetjet sprayingspraying (with(with aa tractor-drawntractor-drawn sprayer)sprayer) a solution ofof PICHLORAME + 2.4 D (0(0.16-0.23. 16-0.23 + 0.6-0.9 kgkg A.S./ha)A.S. / ha) or TRICHLOPYR (0.5(0.5 kgkg A.S.AS/ha)/ ha) in in 350 350 litres litres of of water water perper treatedtreated hectare.hectare.

- Saplings can be treatedtreated only when they are tall enough that the herbicides dodo notnot comecome intointo contactcontact withwith thethe leaves.leaves. ThisThis kindkind ofof treatment can be recommended only if the lowest branches are about 1-1.50 m aboveabove thethe ground.ground. No spray must touch the trunks.trunks . Taking phytotoxicity risks intointo account,account, these are thethe precautionsprecautions toto follow:

- Spraying mustmust bebe aimedaimed andand atat lowlow pressure.pressure.

- The trees mustmust bebe talltall enoughenough andand thethe bolesboles maturemature enough.enough.

- There must bebe nono windwind whilewhile thethe treatmenttreatment isis underunder way.way.

Treatment, effected with portableportable or tractor-drawntractor-drawn sprayers at 300300 litres of waterwater perper hectarehectare savessaves manymany traditionaltraditional tendingtending operationsoperations (roller-(roller­ grinder ++ bush knife).knife). The PICHLORAME ++ 2.42 . 4 D mixturemixture modifies the nature of the adventitiousadventitious floraflora toto thethe benefit of monocotyledonsmonocotyledons (Brachyaria, Paspalum,Pa spal tun , etc.etc.).) .

The value of herbicidesherbicides depends on how much they costcost toto apply.apply. InIn fact, the profitability of suchsuch treatments must be analysed periodically to take account of sometimessometimes rapidrapid changeschanges inin costs.costs .

* RecommendedRecommended method

Adventitious vegetationvegetation cancan be successfully controllcontrollede d by alternatingalternating chemical and mechanical treatments.treatments.

Pre-emergence treatmenttreatment beforebefore plantingplanting retardsretards weedweed establishment.establishment.

During thethe firstfirst year,year, the transplants areare stillstill tootoo small to be treated with herbicides, which can be applied only to windrows;windro ws; lines and inter-lineinter- line areas must bebe cleanedcleaned manuallymanually and/orand/ or mechanically.mechanically.

Starting thethe second year, manual and mechanicalmechanical methmethodsods of cuttingcutting backback the vegetation and controlling it with herbicides should be used in combination, according toto thethe naturenature ofof thethe vegetation.vegetation. - 54 --

In fact, it is importantimportant toto strikestrike aa balancebal a n ce between:betwee n:

- controcontroll of adventitiousadventitious vegetation,vege tation, anda n d

- the presence of asas continuouscontinuous a woodywoody and/orand/or herbaceousherbaceous layerlayer as possible, inin orderorder toto reducereduce erosion.erosion.

3.43.4.2. 2 - ArtificiaArtificiall ppruningruning

This operation is performedper formed to obtain timber with small,smal l t clean knots from species whose natural pruning process isis inadequate,inadequat e, and it helps improve the qualityqual ity ofof thethe harvestedharvested wood.wood .

Artificial pruning isis recommended only for species whwhichi ch dodo notnot developdevelop epicormic budsbuds whenwhen thethe trunktrunk receivesreceives moremore light.light.

The operation consists of eliminating dead and/or liliveve branches from a portion ofof thethe lowerl ower trunk.tru nk. Pruning must be dodonen e eearlyarly in orderorder to optimizeoptimize the production of wood withoutwithout largelarge knots.knots.

Pruning is done by hand, taking care not to wound the trunk or strip the bark. Saws (handsaws(handsaws or long-handled saws) or hand-lever shears are the ideal pruning equipment.equipment .

Pruning isis preferably carriedcarried outout inin thethe drydry season.season. Maximum pruning height inin industrialindustr~al plantations isis 6-76-7 m, which corresponds to the llimitimit to which a rigidrigid singlesingle scalescale cancan be keptkept toto onon aa plotplot consistingconsi sting of severalseveral dozen hectares.

Artificial pruning is anan optionaloptional operationoperation leftleft to thethe forester'sforester' s discretiondiscretion..

It involvesinvolves twotwo oror threethree successivesuccessive sweepssweeps which,which, for reasonsreas ons ofof rationalization, shouldshould bebe combinedcombined withwith silviculturalsilvicul tural operations.operations .

- The firstfirst pruning isis donedone whenwhen thethe treestrees areare stillstill youngyoung (2 to 44 years). All of thethe treestrees are prunedpruned upup toto 2-52-5 metres,metres, toto aa heightheight not exceeding halfhal f ofof theirtheir fullfull height.height .

- After thethe finalfinal cropcrop treestrees havehave beenbeen designateddesignated andand thethe stands t and hashas been thinned, only thethe futurefuture timbertimber treestrees are artificiallyartificiall y pruned any further. TheThe pruned heightheight shouldshould bebe nono moremore thant han two-thirdstwo- thi rds ofof the tree'stree ' s fullfull height.hei ght .

The calendar and pace of artificial pruning operations depend on the characteristics ofof eacheach speciesspecies (architecture,(architecture, growth,growth, etc.).etc.).

The following scheduleschedul e may be suggested:suggested:

FrakéFrake FramiréFramire Samba CedreCedrelal a

1st pruning 2 years 4 years 4 years 4 years

2nd pruning 4 years 4 years 7 years 6 years

3rd pruning 7 years 7 years - - -- 55 -

3.4.3 -- ThinningThinning

The thinningthinning regime is based on thethe resultsresults of thethe TFTC'sTFTC' s variousvarious experimental facilities (CCT-Plots,(CCT-Pl ots, ground controlcontrol facilities, Marynen,

NelderNelder, I etc.).etc.)

In light of thethe significantsignificant incrementsincrements reported, the thinning regime of monospecificrnonospecific plantationsplantations isis characterizedcharacterized by:by:

- early thinnings;thinnings;

- the often considerableconsiderable amountsamounts ofof woodwood removedremoved duringduring thinning;thinning;

- a thinningthinning pacepace thatthat enablesenables thethe standstand toto reachreach itsits definitivedefinitive spacing asas quicklyquickly asas possible.possible.

This thinningthinning regimeregime correspondscorresponds toto aa typetype ofof silviculturesilviculture thatthat aimsaims to obtain maximum yieldyield atat thethe endend ofof rotation;rotation; thethe relationship between wood quality and growthgrowth raterate isis notnot quantified.quantified.

As aa generalgeneral rule,rule, thinningsthinnings areare mademade atat thethe lowerlower levels,levels, to thethe advantage of dominantdominant trees.trees.

The definitive structurestructure ofof monospecificmonospecific standsstands isis most often of thethe monolayermonolaye r type;type; inin fact,fac t, overshadowedovershadowed treestrees areare eliminated.eliminated. TheThe finalfinal densitydensity is such thatthat treetree spacingspacing eliminateseliminates or considerablyconsiderably reduces competition among individuals.

One of thethe problems posed by thinningsthinnings is how to use thethe wood thusthus produced, as thesethese areare smallsmall trees.trees.

At present, there are several options that dependdepend onon thethe naturenature andand size of thethe thinnedthinned trees:trees:

- For wood produced by initialinitial thinningsthinnings ofof medium-rotationmedium-rotation timbertimber plantations (Frake,(Frak6, Framire,Framiré, Cedrela, etc.), which is often characterized by low durability or low heating potential, no use isis envisaged inin thethe shortshort term.term.

- If the wood has good heating potentialpotential oror isis fairlyfairly durabledurable (Teak,(Teak, Badi, etc.),etc . ), it can be usedused asas firewoodfirewood oror constructionconstruction woodwood (stakes, poles, etc.).etc.)

- If the thinned stems are overover 20 cm in diameter,diameter, theythey cancan bebe usedused for postsposts oror smallsmall sawnsawn timber;timber; however,however, thisthis possibilitypossibility dependsdepends on outlets inin locallocal markets.markets.

3.4.4 - Designation of finalfinal cropcrop treestrees

To optimizeoptimize forestryforestry operations,operations, a certaincertain number of stemsstems may bebe designated toto make upup thethe futurefuture stand.stand. The number of trees so designated varies according toto thethe species.species. It oftenoften correspondscorresponds toto thethe finalfinal densitydensity plus thethe numbernumber ofof treestrees toto bebe harvestedharvested inin thethe lastlast thinning.thinning .

The designation ageage depends onon thethe way each species grows. In fact, the trees' definitive architecture mustmust bebe sufficientlysufficiently apparentapparent (by(by ramification,ramification, - 56 -- bifurcation, etc.) to enable the choice of thethe onesones fittestfittest to supplysupply intermediate andand finalfinal products.products.

After the final crop trees havehave beenbeen designated,designated, silvicultural operations (thinning,(thinning, pruning)pruning) aimaim mainlymainly toto benefitbenefit thesethese trees.trees.

The choice ofof treestrees dependsdepends onon twotwo parameters:parameters:

- their phenotype, whichwhich mustmust bebe optimal;optimal;

- their even distribution over the whole plot.

For example, thethe followingfollowing figuresfigures areare suggestedsuggested forfor somesome medium-medium- andand long-rotation reforestation species:species:

Species FramireFramir6 FrakeFraké Cedrela Samba Gmelina Teak

Final density ((stems/ha) stems/hal 70/90 70/9070/90 100/120 100/120 90/100 100/160

Logging diameter (cm)(cm) 50/60 50/6050/60 50/60 50/60 50/60 45/55

Predesignation age (years)(years) 4 4 6 4 6 10

No. of treestrees to designate (stems/ha) 200 200 200 200 200 250

It is sometimes necessary toto make roads to haul out the woodwood resultingresulting from thinning operations.

If the windrowswindrows have totallytotally disappeareddisappeared by naturalnatural decompositiondecomposition about ten years after planting, itit isis recommendedrecommended toto useuse thethe lineslines theythey leaveleave forfor this purpose.

Otherwise, ifif therethere isis an accumulation of heavyheavy,, long-lasting wood, it may be decideddecided toto thinthin thethe centralcentral lineline systematicallysystematically duringduring thethe initialinitial operation. In this case,case, thethe followingfollowing procedureprocedure maymay bebe suggested:suggested :

- systematic thinningthinning toto open removalremoval roadsroads (a centralcentral line) duringduring the initialinitial operation;operation;

- designation ofof finalfinal cropcrop trees;treesi - 57 --

- in subsequent thinnings, gradual elimination ofof stems not selected by selective thinningthinning,, in order to obtainobtain top-gradetop-grade intermediateintermediate and final products.

3.5 - Dendrometric parametersparameters

The silvicultural rulesrules setset forthforth forfor each of the species describeddescribed in this paper were establishedestablished on thethe basisbasis of numerousnumer ous data gathered over the whole lifetimelifetime ofof thethe standsstands concerned.concerned. Trees plantedplanted atat experimentalexperimental facilities or in industrialindustrial standsstands werewere measuredmeasured repeatedly.repeatedly _

Our purpose here is notnot toto gogo extensivelyextensively intointo thethe theoreticaltheoretical andand methodological approachapproach toto the dendrometric description of stands and to thethe development ofof managementmanagement tools.tools. ThisThis informationinformation isis treatedtreated inin depthdepth inin many specialized works (see(see Bibliography).Bibliography).

Nonetheless, itit seemsseems necessary toto recall some of the fundamentals and the path thatthat ledled toto thethe developmentdevelopment ofof forestryforestry rules.rules.

3.5.1 - Dendrometric characteristics of stands

The measuredmeasured oror calculatedcal culated indicatorsindicators correspondcorrespond to thethe standardstandard definitions inin thisthis field,field, andand areare designateddesignated withwith theirtheir standardstandard symbols.symbols.

The site is a "tract of forest with homogeneous ecological conditions and a homogeneous stand where the same silviculture may be practisedpractised throughout, andand where itit maymay bebe hopedhoped thatthat thethe yieldyield from aa particular speciesspecies will rangerange withinwithin givengiven limits"limits" (PARDE-(PARDE­ BOUCHON, 1988).1988).

The productivityproductivity indexindex ("Ip")("Ip") is the mainmain characteristiccharacteristic ofof thisthis homogeneous ensemble calledcalled thethe site.site. The indexindex value quantifiesquantifies the site's inherent potential for the production of wood,wood, alsoalso knownknown as xylogenicxylogenic capacity or degreedegree ofof fertility. This potential depends mainly on the nature of the soil, but also on other factorsfactors relating to climate (rainfall,(rainfall, hygrometry, light, etc.) and to the stand itselfitself (seed(seed provenance,provenance, sitesite preparation,preparation, pace ofof tending,tending, wildfireswildfires,, etc.).etc . ).

- Standstand density ("N")(liN " ) isis thethe numbernumber ofof standingstanding treestrees perper hectare.hectare.

Stand age ("t"),("t"), expressed in full years, is the number of growing seasonsseasons44 elapsedelapsed since transplanting thethe saplings.saplings.

- Basal areaarea ("B")("B") is the sum of the cross-sections of allall thethe treestrees in the standstand atat thethe heightheight ofof 1.301. 30 mm aboveabove thethe ground.ground. It is expressed inin m2ml perper hectare:hectare:

E C2 B -

4 477"IT

Where C = individualindividual circumferencecircumference (girth)(girth) atat 1.301.30 m.m.

4 A growing seasonseason may includeinclude twotwo rainyrainy seasonsseasons ifif thethe climateclimate regimeregime is divided inin thisthis way.way. - 5858- -

This indicator isis useful inin monitoring the development ofof the stand as a whole. It makesmakes it possible to define standstand statusstatus forfor givengiven speciesspecies andand to rapidly compare different stands.stands. A slowdown in its rate of increase shows that the plantation's productive capacitycapacity isis becomingbecoming saturatedsaturated andand thinningthinning is needed.needed.

- Dominant heightheight isis closelyclosely linkedlinked toto sitesite quality,quality, hence to thethe productivity index,index, whichwhich it is usedused toto calculate.calculate. TheThe standardstandard symbol isis "H"H dom,"dem," butbut toto makemake thingsthings easiereasier wewe shallshall useuse thethe symbolsymbol "Hd".

This indicatorindicator representsrepresents thethe averageaverage height,height, in metres, of thethe 100100 largest trees in a hectare. It is of particularparticular interest because itit is little influenced by thinning, especially of smallsmall andand medium-sizedmedium- sized stemsstems atat thethe lower level.level.

- The average heightheight ("Hg")( "Hg " ) ofof aa standstand isis defineddefined byby thethe heightheight ofof itsits "average tree," which is,is, artificially, thethe averageaverage basalbasal areaarea tree.tree. Its cross-section atat 1.301.30 mm is:is:

B (8:(B: basalbasal area; N: number ofof trees/ha)trees/ha) N

This indicatorindicator is veryvery similarsimilar toto dominantdominant height,height, exceptexcept thatthat it varies according to lower-level thinning. It is therefore a stand characteristic thatthat depends on thethe specspecific'ific silviculturalsilvicultural practices.practices. TheThe same is true for:for;

- The mean girthgirth ("Cg")("Cg") andand thethe meanmean diameterdiameter ("Dg")("Og") ofof thethe stand,stand, which corresponds to thethe mean basalbasal areaarea atat 1.301.30 m.m.

EC2 Cg Cg = and Dg = N 7Trr

EC2 = sum of the squared girths of N trees/ha

International standardsstandards measuremeasure treetree girthgirth at the heightheight ofof 1.301.30 mm above the ground. In CoteCfte d'Ivoire'sd'Ivoire's teakteak plantations,plantations, initial measurements were made atat 1.501.50 m.m. It waswas thereforetherefore necessary to keep to this measurement height (provisionally),(provisionally), inin order toto havehave homogeneoushomogeneous datadata forfor yieldyield tables.tables.

The value often takentaken asas averageaverage girth:girth:

E C Cc= = N which is systematically slightlyslightly lessless thanthan Cg,Cg, shouldshould bebe avoidedavoided becausebecause itit leads, among other things, toto furtherfurther underestimationunderestimation ofof B.8.

The spacing factor "S""5" expresses, as a percentage, the ratio of average spacing amongamong treestrees at dominantdominant heightheight in thethe samesame ensemble. - 59 --

e S % = x100x 100 Hd

"e" derives from the stand's residual densitydensity N

10 000 1 0.5

e = v or e = 100100 .• (-)( ) N N

Assuming aa squaresquare distribution,distribution,

10 000 1 0.5

then S %% - (-)( ) Hd N

Note: The spacingspacing factorfactor isis calculated differentlydifferently byby differentdifferent authors; assuming aa hexagonalhexagonal distribution,distribution, itit becomes:becomes:

10 000 e' = v N x 0.866

Either valuevalue maymay bebe used,used, sincesince theirtheir ratioratio isis constant:constant: e/e' = 0.931

In thethe followingfollowing paragraphsparagraphs we shallshall useuse thethe squaresquare distributiondistribution value, forfor reasonsreasons ofof simplicitysimplicity inin calculation.calculation.

This factor isis anan essentialessential standstand characteristiccharacteristic that is much moremore objective than simple density at a givengiven age,age, becausebecause itit describesdescribes stand status at aa preciseprecise stagestage ofo f developmentdevelopment (expressed(expressed byby Hd),Hd), integrating both site fertilityfertility andand plantationplantation age.age.

The spacing factorfactor defines,defines, soso toto speak,speak, a feature of the standstand (it(it decreases overover time),time), and quantifiesquantifies thinningthinning intensityintensity (positive variatvariationion with stem elimination).

Wood production, the objective of reforestation operations, is expressed inin terms of woodwood volumevolume andand increments.increments.

Several different kinds of volume cancan bebe assessed,assessed, dependingdepending onon thethe target. Researchers useuse aa whole rangerange ofof indicatorsindicators toto describedescribe standstand potential: total volume,volume, bolebole volume,volume, mainstemmainstem volume,volume, heavy-timberheavy-timber volume, woody biomass volume,volume, timbertimber volume,volume, etc.etc.

Forest managers concerned with well-defined production, in this case commercial timber, need to use onlyonly the indicators relating toto technological andand economiceconomic constraintsconstraints suchsuch as:as:

- Mainstem volume (abbreviated(abbreviated toto HWV)HWV) isis the volume of wood with bark (stem + branches)branches) in the intervalinterval fromfrom thethe lowerlower cutcut (at groundground level unless the base of thethe treetree isis deformed)deformed) toto thethe upperupper cut,cut, where the girth isis 2222 cmcm (diameter(diameter 77 cm).cm).

- Standing volume "V" is the total HWV of all standing trees (before(before or after thinning) per hectare, expressed inin m3/ha.m3/ha. - 60 --

Thinning volume isis the HWV of treestrees removedremoved by thinning,thinning, expressedexpressed in m3/ha.

Timber volume (abbreviated(abbreviated to TV), inin m3/ha, isis the volumevolume of wood with bark inin the interval between thethe footfoot of the tree and the upper cut at thethe diameterdiameter ofof 3030 cm.em. ThisThis factorfactor correspondscorresponds toto currentcurrent timber use requirementsrequirements (sawing,(sawing, slicing,slicing, peeling).peeling).

- TTotalotal volume, oror "Vtot,""Vtot," isis thethe sumsum ofof thethe standingstanding volumevolume "V""V" atat aa given age plusplus thethe volumevolume extractedextracted inin previousprevious thinnings.thinnings. It too is expressed inin m3/ha.m3/ha.

Mean annualannual increase,increase, oror "mi,""mi," isis thethe yearlyyearly averageaverage ofof thethe totaltotal yield beginning inin the stand'sstand's firstfirst yearyear ofof existence:existence:

Vtot mi - expressed in m3/ha/year t

where tt = ageage inin years.years .

- Current annualannual increaseincrease isis thethe yearlyyearly averageaverage ofof totaltotal yieldyield overover aa given period ofof one or more years, forfor example between ageage xx and age y:

Vv x·yxy i xy - x - y

wwherehere V x.syx.y == VtotVtot atat ageage yy - vtotVtot at age x

Mean increase expresses overalloverall yield,yield, whereaswhereas currentcurrent increaseincrease givesgives an spot imageimage ofof productionproduction atat anyany givengiven age.age.

3.5.23 . 5 . 2 - Volume tables

Forest managers alwaysalways havehave thethe problemproblem ofof assessingassessing thethe intermediateintermediate and final material yield of aa physicalphysical objectobject whichwhich isis determineddetermined byby thethe targets set for thethe standsstands (timber, heavy wood,wood, pulpwood, etc.)etc.).. The quantification of currentcurrent andand averageaverage incrementsincrements inin thisthis materialmaterial providesprovides essential indicatorsindicators forfor forestforest management.management.

Managers must therefore be ableable toto rapidlyrapidly estimateestimate thethe appropriateappropriate volumes atat thethe variousvarious stagesstages ofof thethe stand'sstand's life.life.

For this purpose, volume tablestables havehave beenbeen developeddeveloped onon thethe basisbas is ofof data gathered fromfrom existingexisting stands.stands .

* Measurement of tree volume

Tree volume hashas beenbeen measuredmeasured onon bothboth standingstanding trees,trees, by climbingclimbing them, andand felledfelled trees.trees. The chosenchosen totaltotal volumevolume isis calculatedcalculated byby adding up the volumesvolumes ofof fictitiousfictitious segments,segments, generallygenerally 11 m m long.long. -- 61 --

This volume dependsdepends onon thethe kindkind ofof cut,cut, whichwhich maymay be:be:

- by size:size: + mainstem, diameter 77 cmem + other sizes,sizes, 2020 cm,em, 2525 cm,em, 3030 cm,em, etc.etc.

- by shape:shape: + crown cut,c u t, located at thethe pointpoi nt where a forkfork or aa verticilverticil ofof large branchesbranches originates.o riginates. This cut defines aa bolebol e volume;volumei + merchantable cut.cut. This correspondscorresponds toto the limitlimit upup toto whichwhich merchantable timbertimber cancan bebe obtained.obtained.

The reference diameterdiameter oror girthgirth isis measuredmeasured atat thethe heightheight ofof 1.302.30 m.m. For certain species,species, whenwhen buttressbuttress heightheight reachesreaches oror exceedsexceeds 1.301.30 m,m, the girth isis measuredmeasured aboveabove thethe pointpoint wherewhere thethe buttressesbuttresses end,end, andand this is taken asas thethe referencereference parameter.parameter.

MeasurementMeasurementss include bark, and the calculated volumesvolumes therefore correspond tot o thethe volumesvolumes ofof woodwood plusplus bark.bark.

* Table calculation

For each speciesspecies studied,studied, volumevolume tablestables havehave beenbeen developeddeveloped forfor thethe variouvariouss researchresearch andand managementmanagement targets.targets.

TTheh e methodsmethods usedused inin preparingpreparing thesethese tables,tables, and thethe mathematicalmathematical cchoiceshoices and constraints involved, are perfectly described in spspecializede cialized worksworks to whichwhich thethe readerreader isis referred.referred. For specificspecific stustudies,d ies, details are available inin TFTC working documents on forestry studies of species for which there are plentifulplentiful data, especially time series.

The simplest and most reliable of the chosen formulas, which entail no standard deviation, are parabolic:

vV = a ++ bb D20 2 ororV=a+bD+c V a + b D + CD2 D2

V : expressed inin m3m3

D : diameter at 1.301 . 30 m,m, expressedexpressed inin metres.metres.

Although thethe curvescurves correspondingcorresponding toto thesethese twotwo formulasformulas maymay seemseem nono different at firstfirst glance,glance, to avoid deviation it isis necessarynecessary toto choose the simplestsimplest one, as long as the other presents no significantly smaller residualresidual deviationdeviation (CAILLIEZ-BLANC,(CAILLIEZ-BLANC, 1979).1979).

The modelsmodels are generallygenerally adjustedadjusted byby weightedweighted regression.regression. As is evident, they areare mainlymainly single-entrysingle-entry tables.tables. In practice, forestforest managersmanagers must reconcile thethe precision of theirtheir assessmentassessment toolstools andand the economic aspectaspect ofof theirtheir operations.operations. TheyThey must rapidly obtain reliable quantitative data, often over wide areas,areas, andand accordinglyaccordingly often havehave to shortenshorten measurementmeasurement periods.periods. Research shows thatthat although the use of two-entry tablestables (diameter(diameter andand height)height) givesgives moremore precise data, the improvement isis not significant enough to justify the greater cost of fieldfield operations.operations . - 62 -

* Use of volume tablestables

For each species, tablestables are prepared onon thethe basis of a rather limited number ofof samplesample, trees,trees, whichwhich determinedetermine thethe validityvalidity ofof thethe tables tabl es themselves.themsel ves. Accordingly, these should be used only within the limits so defined.

Where yieldyield tablestables cancan bebe compiledcompiled (Teak, Fraké,Frakl§ I Framiré,Framire I etc.),etc . ) I volume tablestabl es areare usuallyusually thethe lastlast step.step. The validity range of these tables is therefore linked to particular size spreads and wellwell-defined- defined fertility classes.classes.

The user's choicechoice ofof volumevolume tabletable dependsdepends onon thethe assignedassigned target.target.

The mainstem volume widely used as a working basis in this text is a conventional reference.reference.

Bole volume figuresfigures are generally much closer toto the volume that can actuaactuallylly bebe mobilizedmobilized asas timber.timber. When thethe technicaltechnical limitationslimitations on use of the rawraw woodwood materialmaterial areare wellwell known,known, itit isis advisableadvisable toto useuse aa size cut volume.volume . IfIf itit isis necessary toto calculatecalculate timbertimber volume, thisthis corresponds toto thethe 3030 cm-diametercm- diameter cut.cut.

3.5.3 -- YieldYield tablestables

Forest managers must assess and planplan thethe yieldyield ofof theirtheir stands.stands. Accurate data (inventory, volume tables, etc.)etc . ) and a forecast quantification tool must thereforetherefore be available.available. YieldYield tablestables meetmeet these requirements.

The yield tabletable givesgives aa picturepicture ofof thethe probableprobable evolutionevolution ofof anan even-even­ aged monospecificmonospecific standstand overover time.time . It thus makesmakes it possiblepossible toto estimate several of the presumable dendrometric characteristcharacteristicsi cs (number of increment stems, basal area, mean diameter,diameter, volume, increment, etc.) according to age and dominantdominant height, and is effective forfor bothboth standingstanding treestrees andand subsequentsubsequent thinnings.thinnings.

The data referrefer toto hectareshectares and areare setset outout accordingaccording toto periodsperiods ofof time which may be eithereither standardstandard or correspondingcorresponding to the thinningthinning cycle.

Yield tablestables areare compiled:compiled :

- by species

- and, forfor eacheach species,species, byby climateclimate zone.zone .

Within each homogeneous climateclimate zone,zone, thethe tablestables distinguishdistinguish among several "fertilityIIfertility classes"classes II and describe the average evolution of stands toto whichwhich aa givengiven typetype ofof silviculturesilviculture isis applied.applied.

Applied to their reference region, the tables provide figures that are probably accurateaccurate enoughenough to:to:

develop considerationsconsiderations onon aa species' growth and behaviour in a stand;

be used toto supportsupport standstand managementmanagement oror regionalregional economiceconomic studies.studies. - 6363 --

3.5.33.5.3.1. 1 - Construction of provisional yieldyield tablestables

The amountamount of detail inin aa yieldyield tabletable dependsdepends on thethe naturenature ofof thethe available data. Data are gathered on permanentpermanent and temporary plots established inin standsstands representativerepresentative ofof differentdifferent silviculturalsilvicultural stages.stages.

A growth simulationsimulation model cancan thenthen bebe builtbuilt and used to forecastforecast thethe evolution of aa standstand toto whichwhich averageaverage silviculturesilviculture isis applied.applied.

The provisional character of these tables is linked to the extrapolation ofof certaincertain curves,curves, particularlyparticularly forfor ageage groupsgroups thatthat areare notnot yetyet represented inin certaincertain fertilityfertility classes.classes.

Yield tables applyapply onlyonly toto regularregular standsstands ofof aa single'single species.species. They cannot be used forfor mixed stands,stands, wherewhere therethere existexist complexcomplex growthgrowth conditionsconditions which havehave notnot yetyet beenbeen studied.studied .

The tablestables areare compiledcompiled forfor givengiven geographicgeographic regions.regions. TheyThey cancan bebe applied beyond their referencereference areaarea onlyonly withwith thethe greatestgreatest caution,caution, becausebecause changes in the conditionsconditions ofof thethe standsstands' growth environment influenceinfluence treetree growth.

The figures given in thethe tablestables areare averageaverage values.values . TheyThey representrepresent average growth trendstrends forfor aa givengiven speciesspecies inin purepure even-agedeven-aged standsstands inin aa givengiven geographic area.area.

Behavioural and silviculturalsilvicultural treatment variations are takentaken intointo consideration withinwithin thethe limitslimits ofof thethe samplingsampling effected. Tables so developed cannot accountaccount forfor locallocal growthgrowth variationsvariations restrictedrestricted toto smallsmall areas:areas: the goal ofof samplingsampling is to identifyidentify averageaverage trends not overlyoverly influencedinfluenced by particular cases.cases .

The various functions thatthat describedescribe standstand statusstatus areare basedbased onon aa mix of observations made before, betweenbetween andand afterafter thinnings.thinnings.

The yield table construction methodmethod isis basedbased onon the following empiricalempirical laws:

1. The yield per area unit of an even-aged stand depends directlydirectly onon its dominantdominant height, and the total yieldyield inin volumevolume obtainedobtained forfor a givengiven dominantdominant height is not influenced by the number of years needed to reach thisthis heightheight (PARDE,(PARDE , 1961).1961).

This observation makes it possible to classify stands according to dominant height at a given age, and also to define productivity classes.classes.

2. The increase in an even-agedeven-aged stand'sstand's basalbasal area andand volumevolume remains identical withinwithin a widewide rangerange ofof differentdifferent thinningthinning systems (PARDE, 1961). Or, more restrictively (MARSH, hypothesis)hypothesis):: "On a given type of site, the growth ofof aa thinnedthinned stand withwith N stems/ha and ground areaarea G (or(or volume V)V) isis equalequal tot o that of a unthinned stand thatthat has alwaysalways hadhad N stems/ha, atat the age when with those N stems/ha,stems/ha, itit attainsattains thethe basalbasal areaarea GG (or(or the volume V)."V)." FLOWCHART OF PRODUCTION TABLETABLE CONSTRUCTION OPERATOPERATIONSIONS

Measurement protocol

y Creation of data storage Establishment of permanent andand processing trial-plots grid systems

Illr if Successive Data acquacquisition isition inventories

Thinnings

11IF Production of data series, .. volume tables, '... [AnnualAnnual processing stem analyses ...'"

Permanent or complementary semi-temporary trial-plots .. Provisional growth models

4,~ Review of trial-plots.. gridgrid Final growth model at the end of the trial-plots grid's rotation cyclecycle - 6565 -

It is then possible,possible, starting with anan ensembleensemble ofof silvicultural operationsoperati ons appliedapplied toto thethe stands,stands, toto extrapolate growthgrowth lawslaws for a theoretical thinning intensity halfwayhalfway betweenbetween twot wo consecutiveconsecutive thinningsthinnings intensitiesintensities actually appliedappli ed toto thethe sampledsampled stands.stands.

The construction methodmethod usedused isis thethe oneone developeddeveloped byby DECOURTDECOURT (1972),(1972), which considers threethree ratioratio SyStems:systems:

Silviculture-independent ratiosratios

HO: (Age, fertility)

AsAS a general rule,rule, finalfinal density ofof average-rotation speciesspecies isis onon thethe order ofof 70-9070 - 90 stems/ha.stems/ha. Consequently, it is necessary to reconsider the traditional definition ofof dominantdominant heightheight (average heightheight ofof the hundredhundred largest stems/ha)stems/hal as aa functionfunction ofof standstand densitydensity afterafter thethe lastlast thinning.thinning.

Dominant height isis defineddefined asas thethe averageaverage heightheight ofof thethe 50SO largestlargest trees per hectare. The dominant heighthei ght atat aa given age is a good indicator of site fertility.fertility . AsAs such,such, itit makes itit possible toto define productivity classes.classes .

Dendrometric ratiosratios

Hg: (HO, density)

DominantDominant heightheight isis aa functionfunction ofof sitesite densitydensity andand fertility.fertility. For aa given density and age, iti t willwill be everever greater asas thethe sitesite isis more fertile.fertile. SJ.milarly,Similarly, thethe numbernumber ofof dominateddominated treestrees onon aa densedense stand,stand, onon a given site and at a given age, willwill bebe greatergreater thanthan ifif itit hadhad beenbeen heavilyheavily thinnedthinned out.out.

This ratio representsrepresents thethe influenceinfluence ofof sitesite andand silviculturesilviculture onon thethe trees I average height.height.

Cg: (Hg, density)

Mean girth isis relatedrelated toto averageaverage heightheight andand density.density. This ratioratio reflects the influence ofof thinnings onon stand girth growth forfor aa givengiven fertility. Depending onon whether aa stand has or has notnot beenbeen thinnedthinned outout before thethe appearanceappearance ofof competingcompeting vegetation,vegetation, the trees'trees I average girthgirth increment will be larger or smaller, within the biological growth limits of each species.species .

V: (Cg, N)N)

The compilation ofof aa volume tabletable isis essentialessential toto assessassess woodwood volumesvolumes at differentdifferent momentsmoments ofof thethe stand'sstand1s lifetime.lifetime.

Forestry rulesrules

These define thinnings quantitatively andand qualitatively,qualitatively, asas aa guide toto foresters. In particular,particular, thethe following points areare specifiedspecified byby means ofof thethe usual dendrometric parameters:parameters:

- thresholds of thinning operations (G, S%,S96, HO);HO) i

- intensity of thethe variousvarious thinningsthinnings (Ge,(Ge, Ne);Ne ) i

- their cycles (A).(A). - 6666 -

CHAIN DIAGRAMS REPRESENTING A PRODUCTION TABLE

Hd

HgG: (Hd' density) HHd:d: (Age(Age,, fertility)

Increasing fertility t i

Decreasing K, density

Curve 2 Curve -I1

Age Hg Volume

Curve 3 Curve 4

IncreasingIncreasing 4° heightheight

H i

H2

Decreasing H 3 N 4 density

C: (Hdensity) Cg V: (Cg, Hg) g g - 67 --

3.5.3.2 - Establishment of the various ratiosratios

Hd ratioratio (Aqe,(Age, fertility)fertility)

This ratio is often the most complicated to obtainobtain.. It is traditionally found throughthrough successivesuccessive measurements made over several years on permanent plots.plots. However, due to the insufficiency of the data gathered at permanent facilities, itit isis often necessary to use methods which make it possible to assess dominant height variations over time quickly and accurately. This isis thethe reasonreason thatthat stemstem analysesanalyses havehave beenbeen effected.effected .

Multiple regressionregression methodsmethods areare usedused toto constructconstruct thethe setset ofof fertility curves which translate thethe height/age/fertilityheight/ age/ fertility indexindex ratio.ratio.

These methods maymay bebe used toto adjust a set of fertility curves when the fertility index "Ip"1IIp" or thethe fertilityfertility classclass ofof eacheach plotplot cancan bebe determineddetermined before adjusting thethe model.model.

This productivity indexindex isis a brief descriptor of the potential of a given stand, withwith itsits ownown history,history, inin aa givengiven location.location.

Average heightheight ratioratio (Hd,(Hd, N)N)

The average height of a standstand at aa givengiven ageage dependsdepe nds on both sitesite fertility and standingstanding populationpopUlation density.density.

For a given ageage andand sitesite fertility,fertility, thethe dominantdominant height willwill be everever greater asas thethe standstand isis increasinglyincreasingly thinnedthinned out.out . Thinning firesfires more often affect dominated trees,trees, andand thusthus havehave a positive influence on the total height average of thethe treestrees thatthat areare stillstill standing.standing.

Girth evolutionevolution (Hq,(Hg, N)

Average girth incrementincrement (C(C 1.30)1.30) inin a stand is influenced by the site'ssite's fertility and by thethe kindkind ofof silviculturesilviculture appliedapplied toto thethe stand.stand.

Volume V tablestables (Hq,(Hg, Cq,eg, N)NI

These are usually mainstem volumes; coefficients are often calculated to go from mainstem volumevolume toto volumesvolumes thatthat correspondcorrespond toto differentdifferent cuts.cuts.

3.5.3.33 . 5 . 3 . 3 - DescriptionDescription of silvicultural practices

The silvicultural rulesrules defined forfor eacheach speciesspecies vary according toto a certain number ofof ecological,ecological, technicaltechnical andand economiceconomic factors.factors. They must bebe considered as indications thatthat areare adequateadequate toto directdirect butbut not compel forestryforestry work.

To describedescribe inin practicalpractical termsterms a silviculture appliedapplied to a givengiven species, the followingfollowing pointspoints mustmust bebe specified:specified:

- plantingplanting density, which makes it possible to obtain a good general configuration of young plantations with the appearanceappearance of an early "stand effect"; 1

- 68 --

- times for thinning operations. These may be defined byby thresholds of

age,age I dominant oror averageaverage height,height I average heightheight increase, etc. Thinning isis carried outout whenwhen thesethese thresholdsthresholds areare reached;reached;

- operatoperationion intensity.intensity. This is thethe number of stemsstems whichwhich are toto bebe left standingstanding when thethe standstand reachesreaches aa givengiven dominantdominant height.height. The Hart-Becking factorfactor maymay bebe used;used;

- the nature of thethe thinnings,thinnings, characterizedcharacterized byby thethe ratioratio K:K:

Average volumevolume ofof thethe treetree removedremoved byby thinningthinning

Average volumevolume ofof thethe treetree beforebefore thinningthinning

for a given thinning intensity, thethe higher thethe K ratio is, thethe higher the thinning;thinning;

- rotation length as a function of exploitable diameter. The value ofof the exploitable diameter influencesinfluences thethe number of standing stemsstems toto be savedsaved afterafter thethe lastlast thinning.thinning. The higherhigher thethe exploitableexploitable diameter, the more intenseintense thisthis lastlast thinningthinning will be; thethe "vital"vital spacespace"ll needed for a tree's optimum development increases according to itsits growth.growth,

The optimizationoptimization ofof thesethese parametersparameters is a compromise amongamong the characteristics ofof eacheach species,species, inin particular itsits reactionsreactions toto variations inin light (growth habit,habit, pruning,pruning, epicormic buds), and thethe technologicaltechnological andand economic constraints.constrain'ts,

Thinnings may be described by meansmeans ofof thethe followingfollowing parameters:parameters:

- dominant heightheight beforebefore thinning;thinning;

- the number ofof stems before and afterafter thinning,thinning, which maymay bebe specified by the spacing factorfactor before andand after thinning:thinning:

sS ~= ee/Hd/ Hd with E =~ (10 000000/N)1/2/ N)1/ 2

This factor,factor, by meansmeans ofof thethe dominantdominant heightheight deviation,deviation, makes itit possible toto integrateintegrate sitesite fertilityfertility andand standstand age.age,

- The rate of removalremoval expressedexpressed inin basalbasal area:area:

stand's basal area before thinning g stand's basal area after thinningthinning

These ratios werewere establishedestablished from studiesstudies of competitioncompetition and ofof thinning systems.systems,

EconomicEconomic constraints are integrated with the suggestedsuggested silviculturesilviculture atat the level of the nature of thethe products mobilized duringduring thinningthinning andand ofof thethe adopted profitability rate, which determines the exploitable diameter for a given fertility.fertility. - 6969 --

3.5.3.4 -- CompilationCompilation ofof yieldyield tablestables

Yield tables areare compiledcompiled inin stages,stages, accordingaccording toto availableavailable data.data.

* Intermediate tables

The first stage is the one that makesmakes it possible to suggest silvicultural rulesrules forfor aa givengiven species.species. These tablestables describe stands toto which an experimentalexperimental silviculturesilviculture isis appliedapplied aa priori.priori.

The modelling isis static,static, andand only allows very limited extrapolation. Stand status isis expressed inin termsterms ofof age, fertilityfertility classclass andand standstand history.

These methods are static inin the sense that thinnings have no driving role in the model, andand thatthat silviculturesilviculture variesvaries onlyonly withwith thethe applicationapplication ofof certain kinds of well-characterized treatmentstreatments thatthat areare already presentpresent inin the data (ALDER,(ALDER, 1980).1980).

* Provisional tablestables

When thethe quantityquantity ofof availableavailable datadata isis adequateadequate andand representsrepresents aa sufficient number ofof differentdifferent cases of configurationconfiguration (permanent plots monitored forfor manymany years),years), itit isis possiblepossible toto constructconstruct aa staticstatic simulationsimulation model with which toto accurately forecastforecast thethe growthgrowth ofof aa stand toto which various silvicultural treatmentstreatments areare applied.applied.

In particular, provisional yield tables make itit possiblepossible toto modelmodel dlfferentdifferent thinning regimesregimes accordingaccording toto fertility.fertility.

The provisional character of these tables is related to the extrapolation ofof certaincertain curves;curves i this is so particularlyparticularly forfor age classes thatthat are not yet represented inin certaincertain fertilityfertility classes.classes.

* Definitive tablestables

The application ofof certaincertain kindskinds ofof silviculturesilviculture withinwithin aa systemsystem ofof permanent plotsplots tendedtended upup toto thethe endend of the rotation period makes it possible, as inin provisionalprovisional tables, to establishestablish definitivedefinitive tablestables withoutwithout extrapolationextrapolation for certain treatments. Growth isis simulated with static silvicultural models, and the time factor isis aa parameter controlledcontrolled fromfrom thethe momentmoment ofof plantingplanting toto the end of the rotationrotation period.period.

The suggested models maymay bebe dynamic:dynamic: these too are based on expected current growth in termsterms ofof averageaverage diameter,diameter, ground area oror volumevolume asas aa function ofof stand density,density, age andand fertility.fertility. In makingmaking thesethese yieldyield projections, oneone eithereither integratesintegrates thethe growth function mathematically, oror adds up by iterationiteration overover thethe years.years. However,However, toto expressexpress thethe effectseffects ofof density,density, dynamic models require a great quantity of data that give a good representation of extremelyextremely diversediverse densities.densities.

3.5.3.5 -- Validity limitationslimitations ofof yieldyield tablestables

Yield tables concernconcern onlyonly even-agedeven-aged standsstands mademade upup ofof aa singlesingle species.species. -- 70 --

Yield tablestables cannotcannot bebe appliedapplied toto mixedmixed stands,wherestands I where therethere existexist complex growth conditionsconditions thatthat havehave notnot yetyet beenbeen studied.studied. Similarly,Similarly, the existence ofof manymany ageage classesclasses withinwithin thethe samesame standstand make itit too heterogeneous for this classification.

The tables are established forfor a given geographic region.region . They can be applied beyond theirtheir referencereference areaarea onlyonly withwith thethe greatestgreatest caution.caution. InIn fact,fact, changes in thethe growthgrowth environmentenvironment may wellwe l l influencei nfluence the manner of treetree growth.

The figures setset downdown inin thethe tablestables areare meanmean figures.figures. They represent average trendstrends inin thethe growthgrowth ofof aa given species, ini n pure even-aged stands,stands, inin a givengiven geographicgeographic area.area These stands are subjectedsubjected to aa well-definedwell-defined ensembleensemble of silvicultural practices.practices .

Particular variations inin behaviour are taken into considerationconsideration within the limits of thethe sampling effected.effected. TablesTables soso developeddeveloped willwill notnot bebe ableable toto account forfor locallocal growthgrowth variationsvariations restrictedrestricted toto smallsmall areas:areas: the goal of sampling is toto identifyidentify average trendstrends that are notnot overlyoverly influencedinfluenced by particular cases.cases.

The forecastforecast of a stand'sstand's growth must be mademade within the samplingsampling carried out. Extrapolations beyond sampling limitslimits are subject toto error.error . - 7171 --

CHAPTER IIIIII

SILVICULTURAL RULESRULES FORFOR THETHE PRINCIPALPRINCIPAL REFORESTATIONREFORESTATION SPECIESSPECIES

Numerous trialstrials havehave beenbeen conductedconducted withwith thethe reforestationreforestation speciesspecies suitable forfor timbertimber production.production.

In the framework of the reforestation programmes implemented in C8teCote d'Ivoire, it has beenbeen consideredconsidered advisableadvisable to summarize the findingsfindings with regard to the species potentially of interest to silviculture andand protectionprotection reforestation.

The followingfollowing availableavailable resultsresults havehave beenbeen summarizedsummarized forfor eacheach speciesspecies tested in monospecies trials:trials:

- the biogeographical characteristics ofof its natural rangerange (annual rainfall, duration of dry season,season, altitude);altitude) i

- the chie~chief properties of the wood (density, mechanical characteristics, impregnability,impregnability, seasoning,seasoning, ...)... ) that determinedetermine itsits technological vocation;vocation;

- the major plantplant protectionprotection problemsproblems that couldcould compromisecompromise successfulsuccessful plantations,

- the dendrometricdendrometric parameters of the stands, describingdescribing initial growthgrowth and thinning thresholds forfor optimumoptimum growth.growth. The silvicultural rules have been established for single-species, even-aged stands planted on non-marginal sites (bioclimatic(bioclimatic and meso-ecological standpoints

soil, topography,topography I •••...). ). The dendrometricdendrometric parameterparameter valuesvalues (mean height, mean diameter,diameter, basalbasal area,area, ...... ) ) are purely indicativeindicative andand must be adjusted inin relation toto thethe growth conditionsconditions ofof eacheach stand.stand. The figuresfigures given forfor meanmean volumevolume incrementincrement referrefer toto standingstanding timber; the products of thinning operations have not been taken into account, as their commercialcommercial exploitationexploitation isis notnot yetyet assured.assured. The question of the thinning products willwill be briefly dealt withwith inin thethe paragraph entitled "volumetrvolume ofof production";production!!;

- the best provenances toto use,use, whenwhen known.known.

For some species, due to thethe scantscant datadata presentlypresently available,available, only provisional silvicultural rulesrules have been given, which willwill requirerequire moremore precise specification asas additional datadata become available from plantationsplantations now being harvested oror toto bebe establishedestablished inin future.future.

The species have been divided intointo fourfour groupsgroups inin relationrelation toto theirtheir behaviour on single-speciessingle-species plantations:plantations:

- Species with slowslow initialinitial growth.growth .

These are medium-rotationmedium- rotation andand long-rotationlong-rotation species that were formerly used forfor reforestation, many ofof which have been - 7272 --

abandoned due to their excessive silvicultural,silvicultural, phytopathologicalphytopathological or economic disadvantages,disadvantages, suchsuch as:as:

sipoSipo (plant(plant rearing problems and insufficientinsufficient growth),growth) ,

Mahogany (attacks(attacks byby borers),borers) ,

Niangon (insufficient(insufficient growth),growth) ,

OkouméOkoume (insufficient(insufficient growthgrowth andand shapeshape problems).problems)

- pilotPilot species forfor industrialindustrial reforestation.reforestation.

These are fullfull sunlightsunlight speciesspecies with fastfast initialinitial growth andand aa medium or long rotation, and that grow satisfactorilysatisfactorily onon mechanizedmechanized commercial plantations.plantations.

For these species (Fraké,(Frake, Framire,Framir6, Samba, Cedrela), which at presentpresent account for the majority of planted areas, the silvicultural rules are well known.known. Yield tables makemake it possible to modelmodel the growthgrowth of "Teak, Fraké,Frake, CedrelaCedrela andand Framir6Framire plantations.plantations.

- Species toto be promotedpromoted forfor industrialindustrial reforestation.reforestation.

These are fullfull sunlight species with medium to fast initial growth and a medium rotation (Gmelina, Badi, Pines),Pines) , that grow satisfactorilysatisfactbrily on mechanized plantationsplantations and whose introduction on concessions is foreseen toto cover severalseveral hundredhundred hectares.

'Provisional silviculturesilviculture rules have been drawn up based on experimental plantationsplantations currentlycurrently beingbeing harvested.harvested .

- Species toto bebe confirmed.confirmed.

These are full sunlight species - whose behaviour has been successfully testedtested onon trialtrial plots andand whichwhich are to be the object of supplementary experimentation:experimentation: Padouk,Padouk, Cordia,Cordia, Pouo,Pouo, Makore.....Makore ....

1 -- LONG-ROTATION SPECIESSPECIES

1.1 -- Teak (Tectona(Tectona grandis)grandis)

Teak belongs toto thethe VerbenaVerbena family.family. It is aa deciduousdeciduous -lovingsun-loving species that prefers moist semi-deciduous forests.forests. ItsIts rangerange isis discontinuous, and comprises three major zones:zones:

- the Indian peninsula,

- Myanmar, LaosLaos andand Thailand,Thailand,

- the ofof JavaJava andand MunaMuna (Indonesia).(Indonesia) .

In this area rainfall varies between 1i 100 mm and 2 700 mm per year (in limitedlimited locallocal areasareas it may reach 4 000 to 5 000 mm perper year);year); Teak grows from -level toto anan altitudealtitude ofof 11 000000 m.m. - 73 -

In CoteCâte d'lvoired'Ivoire teak was introduced inin 1926 in the forest zone (Banco(Banco forest) and inin 19291929 inin thethe pre-forestpre-forest zonezone (Bouak6(Bouake region).region) .

It starts flowering in May and continues until September, peaking in July. Fruit-setting followsfollows inin September, and isis atat itsits peakpeak inin December-December- January.

Reproduction beginsbegins very early: thethe firstfirst flowersflowers appear between thethe age of 2 years and 8 years, depending on provenances.provenances. In selecting provenances, preferencepreference willwill bebe givengiven especiallyespecially toto thethe late-bloominglate-blooming ones,ones, as first bloombloom heightheight andand forkfork heightheight areare closelyclosely linked.linked. The flowers are apical, and afterafter thethe bloombloom stemstem hashas withered,withered, thethe secondarysecondary laterallateral axesaxes develop and sometimessometimes givegive riserise toto forks.forks.

The main criteria for selecting provenances or treestrees are vigour, forks

(late flowering)flowering), I striae, bumpsbumps andand naturalnatural pruning.pruning.

Provenance trials in West Africa have not revealed any great differences inin vigour, but have demonstrated the superiority, in qualitativequalitative terms, of certain EastEast AfricanAfrican andand AsianAsian provenancesprovenances (SOUVANNAVONG,(SOUVANNAVONG, 1983).1983).

As regardsregards thethe testedtested provenances,provenances, thosethose fromfrom WestWest AfricaAfrica flowerflower andand fork sooner thanthan thosethose fromfrom EastEast AfricaAfrica andand Asia.Asia. The samesame provenanceprovenance distribution alsoalso appliesapplies to naturalnatural pruning height.height . The choice of provenances is thusthus basedbased essentiallyessentially onon plantplant shapeshape criteria.criteria. The bestbest tested provenances are:are; MTIBWA (),(Tanzania), BAN CHAMCHAM (Thailand),(Thailand), BAN PHA LAI (Thailand) and PAKSE (Laos).(Laos).

The rootroot systemsystem isis of the taproot type, with lateral rootsroots developingdeveloping progressively asas thethe treetree ages.ages.

Young Teak plantation;plantation; TENETENE stationstation - 74 --

The fruitfruit (1 000/kg)OOO/kg) containscontains 22 to 4 seeds,seeds, and itsits thickthick pericarppericarp tends toto induceinduce dormancy.dormancy. Soaking the fruits in water forfor 4848 hourshours is recommended toto reducereduce dormancy.dormancy . A mature tree bears 2 to 4 kg of fruit. As the seedsseeds areare hardhard toto extract,extract, thethe fruitsfruits areare usedused toto obtainobtain seedlings.seedlings.

Teak has very good stump sprouting ability; twotwo techniques cancan be used for vegetative propagation (SOUVANNAVONG,(SOUVANNAVONG, 1983):1983):

- shield budding on stumps in March-April at the timetime when buddingbudding occurs atat thethe beginningbeginning ofof thethe rainyrainy season;season;

- plant cuttingscuttings (young(young 22 oror 33 week-oldweek-old terminalterminal shoots);shoots) i

The wood, whichwhich isis yellowyellow toto brownbrown inin colour,colour, is of medium density (density at 12 percent moisture contentcontent == 0.60.6 -- 0.7), medium hardness (semi-(semi­ hard),hard) I with low nervosity,nervosity, low shrinkage, goodgood durability,durability, low impregnability,impregnability, good to medium axialaxial cohesiveness and mediummedium transversaltransversal cohesivenesscohesiveness (DURAND,(DURAND, 1983)1983). .

Its calorific value of 5 000000 cal/g makes it a good fuelwood.fuelwood. It isis used forfor saw-logs,saW-logs, veneer-logs,veneer-logs, indoor and outdooroutdoor woodworkwoodwork andand cabinet-cabinet­ making.

The chief phytopathologicalphytopathological problemsproblems reportedreported are:are:

- attacks of root-rotroot-rot (Fornes(Fomes lignosuslignosus,1 Ganoderma spp.), leadingleading toto destruction of thethe taproottaproot andand windrowwindrow inin thethe evergreenevergreen zone;zone;

- black spotting of thethe woodwood causedcaused by scolidaescolidae and aboveabove allall byby bostrychidae (coleoptera),(coleoptera),

- defoliation duedue toto anan orthoptera:orthoptera: ZoonocerusZoonocerus variegatus,variegatus 1

- termite attacks, chiefly inin thethe savannahsavannah zone.zone.

SILVICULTURAL RULES

For this species there is a yield table applicable to all teak standsstands in C8teCote d'Ivoire (MAITRE,(MAITRE , 1983;1983; DUPUY,DUPUY, 1990).1990).

The recommended plantingplanting densitydensity isis 11 500500 stems/ha.stems/ha .

Teak has averageaverage initialinitial growth-rategrowth-rate.. UnderUnder favourable conditions, the mean total height isis 1010 mm atat thethe ageage ofof 4-54-5 years,years, andand 1414 mm atat 9-109-10 years.years.

On sites of fair and medium fertility, the rotation cycle iiss 50- 60 years for an exploitable diameter of 45-5045-50 centimetres.centimetres.

The general criteria for thinning should be such that logginglogging,, while maintaining aa highhigh productivityproductivity level,level, does notnot causecause excessiveexcessive laterallateral exposure of the trunkstrunks toto sunlight.sunlight. If the lateral lighting increasesincreases tootoo sharply, this will give rise to the appearance of epicormic branchesbranches detrimental to the quality ofof thethe futurefuture wood.wood. - 75 -

VARIATION ININ MEANMEAN DIAMETERDIAMETER (Do)(DG) AS A FUNCTION OFOF AGEAGE ANDAND FERTILITYFERTILITY INDEXINDEX AFTER APPLYING THETHE YIELDYIELD TABLETABLE RECOMMENDATIONSRECOMMENDATIONS (MAITRE(MAITRE 1983)1983)

I E5 R p E1 E2 E3 E4 E5 E7

5 9 18 30 38

48 (cm) 6 7 12 21 33 65

7 5 9 15 23 33 45 60 lp = 8

8 4 7 11 17 24 32 42 55

Thinning calendar /I p

50 lp = 7

lp = 6 40

30

I, = 5

20

E :Thinning Thinning R:R: Final felling

10

10 2020 30 40 50 60

"Age (years)"(years)" - 76 --

The imperative rulesrules areare thethe followingfollowing (SOUVANNAVONG, 1983): 1983):

a felling cycle of over 3 years in young stands and 5 years in old stands,

a basal area felling rate of lessless than:than: * 40% before thethe ageage ofof 1212 years,years, * 30% between 121 2 andand 2525 years;years; * 25% after the ageage ofof 2525 years.years.

If thethe fforestorest manager wants to obtain high exploitable diameters,diameters, thethe thinning schedulesschedules areare asas follows:follows:

THINNING SCHEDULES FOR DIFFERENT FERTILITYFERTILITY LEVELSLEVELS

Fertility levellevel Thinning

operation 1 2 3 4 5

1 NaveN ave (stems/ha)(stemslha) 1I 450 1I 450 1I 450 I1 450 14501 450 Age (years) 3 4 5 6 9 Ave dg. (cm)(cm) 10.5 11.0 11.0 10.7 10.9

2 NNave ave (stems/ha)(stems/ha) 750 750 750 750 750 Age (years) 6 8 10 13 20 Ave dg. (cm)(em) 16.4 16.9 16.6 16.1 18.0

3 NNaveave (stetns/ha)(stems/ha) 400 450 450 450 450 Age (years) 10 12 16 23 35 Ave dg.dg. (cm)(em) 24.0 22.7 22.7 22.7 22.7

4 NNave ave (stems/ha)(stems/ha) 250 300 300 300 300 Age (years) 15 19 24 35 55 Ave dg. (cm)(em) 32.4 30.6 29.7 29.5 30.0

5 NNave ave (stems/ha)(stemsfha) 165 200 210 200 Age (years) 20 26 32 47 Ave dg. (cm)(cm) 40.6 38.7 36.8 37.2

6 NNaveave (stems/ha)(stemslha) 115 140 155 Age (years) 27 35 41 Ave dg. (cm)(cm) 49.9 47.5 45.7

ClearClear felling:felling: N aveaYe (stems/ha)(stems/ha) 85 105 112020 140 225 Age (years) 37 44 49 62 68 Ave dg. (cm)(em) 59.9 55.3 50.2 45.145.2 35.1

(N ave: density before thinning. Dg: diameter ofof thethe tree with thethe average basalbasal area).area) .

The manager may alsoalso envisageenvisage thethe possibilitypossibility ofof choosingchoosing lowerlower harvesting ages.ages. The last thinning operation may be eliminated andand the finalfinal harvest (clear(clear felling)felling) carriedcarried outout earlier.earlier. - 77 -

Depending on the managermanagers r S objectives,obj ectives I thethe silviculture recommendations have the followingfollowing features:features:

- a thinning scheduleschedule withwith fromfrom 33 toto 66 thinningsthinnings dependingdepending uponupon fertility andand exploitableexploitable diameter;diameter;

- a felling cycle of between 33 and 12 yearsyears dependingdepending on fertility and stand age;age;

- an exploitable age ranging from 35 to 68 years depending on fertility andand exploitableexploitable diameter.diameter.

The productivity ofof TeakTeak plantations isis conditioned inin thethe first place by thethe "fertilityIIfertility level"level " ofof thethe sitessites concerned.concerned. The productivity gradient is closely dependent onon thethe rainfallrainfall regime.regime. The highest production figuresfigures are recorded inin the closedc l osed forest zoneszones where the rainfall isis highest and best distributed.

SILVICULTURE RECOMMENDATIONS AND PRODUCTIVITY DATA FOR TEAK

Fertility Number ofof Exploitability Mean increment thinnings Age Dg V Final Total (yrs) (em)(cm) (m3/ha)(m' /ha) harvest harvest

(m3/ha/yr)

LARGE EXPLOITABLE DIAMETER

1 6 37 60 363 9.8 15.8

2 6 44 55 360 8.2 12.8

3 6 51 50 315 6.2 9.7

4 5 62 45 276 4.5 6.9

5 4 68 35 229 3.4 4.8

MEDIUM EXPLOITABLE DIAMETER

1 5 35 55 401 1l.511.5 16.1

2 5 40 50 372 9.3 13.2

3 4 45 45 309 6.9 10.0

4 4 56 40 290 55.2. 2 77.1.1

5 3 55 30 205 3.7 55.0. 0

(V: VolumeVolume of mainstemmains tern inin m3/ha)m3/ha)

The productivity of TeakTeak plantationsplantations varies betweenbetween 55 m3/ha/yearm3/ha/year andand 16 m3/ha/year. - 78 -

Fuelwood-gatheringFuelwood-gathering on Teak plantations

In the closed forestforest zone,zone, thethe meanmean incrementincre ment inin mainstemmainste m volumevolume isis between 10 and 1616 m3m3/ha/year./ ha/ year. This is in fact the zone where Teak grows best.best . In the pre-forest zonezone thethe standsstands havehave aa mediummedium raterate ofof growth.growth . Their mean volume increment isis betweenbetween 77 andand 1010 m3/ha/year.m3/ha/year. In the savannahsavannah zone, thet he rate of growthgrowth isis low. The mean volumevolume incrementincrement isis betweenbetween 5 andand 7 7 m3m3/ha/year./ ha/year .

The silviculture recommendationsrecommendations for the various reforestation zones are thus based on a compromise between size,size, exploitableexploitable ageage andand productivity.p r oductivity .

ROTATIONROTAT I ON CRITERIACRITERIA FORFOR TEAKTEAK REFORESTATIONREFORESTATION PLANTATIONSPLANTATIONS IN RELATION TO FORESTFOREST ZONESZONES

Forest zone Moist closed Pre-forest GuineanGuinean forest area savannah

Exploitable diameterdiameter(cm) (em) 4455 to 60 40 toto 4545 30 toto 4040

Exploitable ageage (years)(years) 35 toto 5050 45 toto 6060 55 to 7070

Mean incrementincrement (m3/ha/year)(m3/ha/year ) 10 toto 1616 7 to 10 S5 to 77

The final harvescharvest constitutesconstitutes approximatelyapproximately 7070 percentpercent ofof thethe totaltotal yield.yield . - 7979 --

1.2 -- OkouméOkoume (Aucoumea(Aucoumea klaineana)klaineana)

The OkoumeOkoumé's' s which isis a member of the BurseraceaeBurseraceae family, is a species native toto thethe moistmoist evergreenevergreen equatorialequatorial forestforest (Gabon,(Gabon, Congo, EquatorialEquatorial Guinea)Guinea).

In OkoumélsOkoume I s originalori ginal range,range, rainfall varies fromfrom 1 500 to 3 500 mm/year, thethe drydry seasonseason lastslasts 11 toto 33 monthsmonths andand altitudealtitude rangesranges fromfrom 11 toto 600600 metres.metres .

It is a sun-loving, gregarious andand socialsocial speciesspecies thatthat colonizescolonizes gapsgaps and clearings.clearings . In natural forest, it grows in clumps or scattered spinneys; free-standingf r ee- standing treestrees areare rare.rare .

Under closely spaced conditions, single-speciessingle-species . standsstands ofof OkoumeOkoumé become ranked in tiers, separating intointo severalseveral storeysstoreys fromfrom thethe ageage of 10-15 years.

On plantations, individualindividual treestrees subjectsubject toto heavyheavy competitioncompetition developdevelop a stuntedstunted crown;crown; sudden exposure of thethe trunktrunk toto lightlight (windrow, heavy thinning) gives rise to anan explosiveexplosive outgrowthoutgrowth ofof epicormic branches,branches, frequently accompanied byby aa droopingdrooping crown.crown .

In its area of origin, thisthis speciesspecies bearsbears fruitfruit inin thethe rainyrainy seasonseason (December-January), starting fromfrom thethe ageage ofof 10-1510-15 years.years. The fruit (10(10 000000 seeds/kg) isis aa drupe that ripens about threethree months after flowering. In CoteCae dd'Ivoire,' Ivoire, the OkouméOkoume sets fruitfruit atat aroundaround 9-109- 1 0 · yearsyears ofof age.age. It hashas twctwo fruiting periods, oneone inin February-MarchFebruary-March andand thethe otherother inin August-September.August-September.

The roots of this species, which consist of a taproot in youngyoung plants, develop very rapidlyrapidly intointo creepingcreeping rootsroots withwith anastomoticanastomotic formations.formations. The OkoumeOkoumé has aa very goodgood stumpstump sproutingsprouting abilityability upup toto thethe ageage ofof 10-1510-15 years.years. It can be propagated by cuttingscuttings andand byby bottlebottle grafting.grafting.

Its soft, light wood (012(D12 .= 0.4/0.5)0.4/0.5) driesdries easily,easily, withwith lowlow toto mediummedium shrinkage. Peeling for veneering, which is the chief use of this wood, can be carried outout withoutwithout difficultydifficulty afterafter controlledcontrolled seasoning.seasoning . ItIt isis idealideal forfor plywood, andand isis alsoalso usedused forfor indoorindoor woodworkwoodwork andand furnishings.furnishings.

In tree nurseries psyllid attacks are frequent, above all in the rainy season (preventive(preventive andand curativecurative treatmentstreatments withwith Vamidothion).vamidothion) .

OkouméOkoume plantations, standsstands onon formerformer clearingsclearings and stands subject toto very brutalbrutal thinningthinning oftenoften suffersuffer fromfrom attacksattacks ofof blackblack canker.canker. This isis aa complex infection thatthat combines a primary attack (bites)(bites) by scale carriedcarried byby Sangounas antsants (Wassmania auropunctata,auropuncta ta, Creamtogaster spp.,spp., ...... ) ) wiwith t h a secondary attackattack byby fungifungi (Botryodiplodia(Botryodiplodia theobromae).theobromae). It is accompaniedaccompanied by dripping sapsap andand thethe externalexternal proliferationproliferation ofof smutsmut fungusfungus whichwhich blackenblacken thethe bole andand branches.branches.

SILVICULTURAL RULES

To reducereduce blackblack cankercanker problems,problems, plantations on formerformer clearingsclearings heavily infestedinfested withwith SangounasSangounas antsants are to bebe avoided inin all cases.cases. Preference for OkoumeOkoumé should be onon totallytotally clearedcleared primaryprimary or secondarysecondary forestland: planting immediatelyimmediately afterafter clearing.clearing. - 80 --

In consideration of tree shape, planting densities of the order of 1 100 stems/ha shouldshould bebe chosenchosen toto allow thethe selection of a sufficient number of well-formed treestrees toto reachreach fullfull maturity.maturity.

At the age of one year, the mean total height is approximately 0.750.75 m, at two years itit isis 1.51 . 5 m,m t atat threethree yearsyears 33 m,ffi, andand atat tenten years,years, 1515 m.m.

The recommendedrecommended thinning schedule involvesinvolves vigorousvigorous thinningthinning operationsoperations in the early years.years. It is in fact hard to salvage young Okoum6Okoume trees that have beenbeen poorlypoorly cultivatedcultivated (in overcrowded stands or withwith uncontrolleduncontrolled regrowth): they are punypuny andand misshapen, andand areare frequentlyfrequently infestedinfested byby blackblack canker when they are suddenlysuddenly exposedexposed toto lightlight byby heavyheavy thinningthinning oror spacing.spacing. The thinningthinning scheduleschedule isis asas follows:follows:

- 4-5 years : thinning-out toto bring density down to 300-350 stems per hectare;

- 9-12 years : first thinning operation to reduce plantation density to 200-250200-250 stems/ha.stems/ ha. This involves spacing out the trees scheduled for full maturity (100(100 stems/ha)stems/ha) andand thinningthinning thethe restrest ofof thethe stock,stock, following two imperativeimperative rulesrules with regardregard toto thethe latter:latter: preservation of thethe well-shaped,well-shaped, well-grown stems in thethe co-co­ dominant storeystorey thatthat dodo notnot competecompete withwith thethe treestrees scheduledforscheduled for full maturity; preservation of a girdlegirdle ofof dominateddominated treestrees aroundaround thethe treestrees

scheduled forfor fullfull maturity,maturity I so asas toto protectprotect thethe latter'slatter's trunks fromfrom excessiveexcessive sunlight.sunlight.

Before thinning,thinning, the mean totaltotal heightheight isis 13-1513-15 metres,metres, the mean circumferencec ircumference isis 55-6055-60 cmcm andand thethe basalbasal areaarea 1010 toto 1212 m2/ha.m2 / ha.

- 14-16 years: aa secondsecond thinningthinning operationoperation toto reducereduce densitydensity toto 150150 stems/ha, aboutabout 100100 ofof which areare toto be trees scheduled forfor maturity in the dominant storey.storey . This thinning will be based essentially onon tree shape, andand carecare will be takentaken to limitlimit competition betweenbetween thethe trees scheduledscheduled forfor maturitymaturity andand thethe restrest ofof thethe stock.stock .

Before thinning thethe mean total height will be 20-22 metres, the mean circumference 90-100 mm andand thethe basalbasal areaarea 1616 toto 1818 m2/ha.m2/ha.

The maximum mean volumevolume incrementincrement isis attainedattained aroundaround thethe ageage ofof 28-3028-30 years, and isis ofof thethe orderorder ofof 1414 m3/ha/year.m3/ha/year. A rotation cycle of 40 years is foreseen for an exploitable diameterdiameter ofof 6060 centimetres.centimetres. - 81 -

VARIATION IN MEAN GIRTH AS A FUNCTIONFUNCTION OFOF DENSITYDENSITY ANDAND AGEAGE FORFOR OKOUME ININ THE MOIST EVERGREENEVERGREEN FORESTFOREST ZONEZONE

C (em)

150 200stems/ha

400 slems/ha

100 600 5 tems/ha

50

MP- I I I 1 I 5 10 15 20 2525 Age (years)(years) - 82 --

1.3 - NiangonNiancron (Tarrietia utilis)utilis)

The Niangon, whichwhich belongsbelongs toto thethe SterculiaceaeSterculiaceae family,family, is a moist evergreen forestforest speciesspecies nativenative toto WestWest Africa.Africa. Its range extends from SierraSierra Leone toto Ghana, withwith meanmean annualannual rainfallrainfall overover 11 800800 mm/yearmm/year andand aa drydry seasonseason of less thanthan threethree months.months.

It is a gregariousgregarious species, sun-loving but able to bear some degree of cover, although underunder thesethese conditionsconditions itsits growthgrowth isis decreased.decreased.

In natural stands, Niangon nevernever growsgrows very big: it is unusual to find individual trees with diametersdiameters exceedingexceeding 0.80.8 toto 11 m.m.

Niangon growing freefree ofof cover,cover, 1414 yearsyears oldold (1976);(1976) Yapo forest

The fruitfruit isis aa samara.samara. TheThe treetree setssets fruitfruit inin December-January,December-January, andand sometimes again inin June-July.June-July. Heavy fruitingfruiting takestakes place once everyevery twotwo toto four years.years.

The wood, of aa pinkish-brownpinkish-brown toto reddish-brownreddish-brown hue, isis lightlight to semi-semi­ light (D12(D12 == 0.6-0.7),0.6-0.7), ofof mediummedium hardnesshardness (soft(soft toto semi-hard),semi-hard), andand mediummedium - 83 --

nervosity. Its mechanical properties (transversal(transversal andand axial cohesiveness) areare in the medium range.range.

Seasoning must bebe gradualgradual to avoidavoid warping.warping. TheThe wood'swood ' s naturalnatural durabilitydurabil ity isi s averageaverage andand itsits impregnabilityimpregnability isis poor.poor.

ItsI ts characteristicschar acteristics make itit a desirabledesirabl e woodwood forfor cabinet-making,cabinet-making I veneering,veneering , decoration,decorati on, andand indoorindoor andand outdooroutdoor woodwork.woodwork.

This species is subject to attack by manymany insects, especially coleopteracol eoptera (bud(bud borers)borers) andand lepidopteralepi doptera (bud(bud andand trunktrunk borers,borers, defoliators).defoliators). The impacti mpact of these attacks isis generally slights l ight and in no way prejudicesprejudices the ffutureuture of the stands.stands. Locally,Local ly, ini n somesome elderlye l derly stands,stands, therethere may be internalinternal bolebol e rot.rot.

SILVICULTURAL RULESRULES

Niangons are traditionallytraditionally plantedplanted outout atat thethe ageage ofof 11 oror 22 years,years, asas talltal l bare-rooted saplingssaplings 11 toto 22 m m high.high. However,However, trialstrials withwith baggedbagged plants only a few months oldold havehave givengiven satisfactorysatisfactory results,results, onon thethe conditioncondition thatthat adequate carecare isi s provided.provided .

Niangon growth-rate isis average:average: atat 11 year thethe mean totaltotal height isis 0.50.5 to 11 m,m, at 2 yearsyears it isis 1.51.5 toto 22 m, and atat 33 and 44 yearsyears itit isis 3-3.53 - 3.5 and 4-4.5 m respectively.respectively.

Because of itsits gregariousgregarious temperamenttemperament andand certaincertain shapeshape problems,problems, aa pplantingl anting density ofof 11 100-1100-1 500500 stems/hastems/ha isis recommended.recommended.

Unlike many other species, the Niangon can stand crowdingcrowding very well. At age 40, the average increment inin the diameter of the largest 150 stems/ha is 1 em/year,cm/year, regardless ofof thethe densitydensity (SOUVANNAVONG,(SOUVANNAVONG, 1978).1978).

The recommended scheduleschedule isis asas follows:follows:

At 6-8 years, thinning-outthinning-out toto bringbri ng thethe densitydensity downdown toto 700-800700-800 stems/ha whenwh en thethe average height isis 8-108-10 m.m.

At 12-1412 - 14 years, thinningthinning toto reducereduce densitydensity toto 400-450400 - 450 stems/ha.stems/ha. TThehe mean diameter before thinningthin ning isis 14-1614-16 cm.cm.

At 50 years, atat thisthis density,density, thethe basalbasal areaarea isis 3535 toto 4040 m2/ha,m2/ha, the mean diameter 3535 toto 4040 cmcm andand 150150 stems/hastems/ha havehave reachedreached thethe exploitable diameterdiameter ofof 5050 cm.cm . The totaltotal volumevolume of of merchantable merchantable volume (diameter>7cm)(diarneter>7cm) is then 550 to 600600 m3m3 perper hectare,hectare, 400400 m3/ha of which consistsconsists of stemsstems thatthat havehave reachedreached thethe maturemature exploitable diameter.diameter.

At around 18-20 years, a second thinning to lower densitydensity to its finafinall level ofof 200200 toto 250250 stems/ha.stems/ha. The mean diameterdiameter beforebefore thinning isis 2020 toto 2222 cm.em.

For an exploexploitablei table diameter ofof 5050 cm, thethe harvesting age isis 5050 years.years. - 84 -

_

VARIATION IN MEAN DIAMETER AS A FUNCTION OF AGE AND DENSITY FOR NIANGON

C (em)(cm)

40 '

400 stems/ha

30

700 stemS/ha 20 C J ----- /' /' - 10lo

10 20 30 4040 50 AgeAge (years)(years) - 85 -

1.4l.4 - Badi (Nauclea()

The BadiSadi oror BilingaBilinga belongsbelongs Loto thethe RubiaceaeRubiaceae family.family. It is an evergreen speciesspecies nativenative toto moistmoist evergreenevergreen forestsforests andand transitionaltransitional toto moistmoist semi-deciduous forests.forests. The Badi reaches a total height of 3030 Loto 4040 m andand aa diameter ofof 0.900.90 toto 1.201.20 m,m, with a slender, straight,straight, branchless,branchless, cylindrical bole risingrising toto aa heightheight ofof 2020 toto 3030 m.m.

This species isis foundfound fromfrom Sierra Leone to Cabinda and eastwards as far as . Rainfall variesvaries inin itsits rangerange fromfrom 11 600600 mm/yearmm/year toto 33 000000 mm/year.mm/year.

This sun-loving speciesspecies hashas aa broadbroad sphericalspherical crowncrown andand thickthick foliage.foliage. It regeneratesregenerates abundantlyabundantly inin gapsgaps andand openings.openings . On plantationsplantations inin thethe evergreen zone (Yapo(Yapo and l'Abbé1 'Abbe in CoteCate d'Ivoire)d'Ivoire) manymany naturallynaturally regeneratedregenerated trees colonized the gapsgaps andand slopeslope bottomsbottoms.. OnOn permanently hydromorphic soilssoils it gives way toto thethe BahiaBahia (Mitragyna(Mitragyna ciliata).ciliata) .

6 year-old Badi growing freefree ofof covercover (1984);(1984) YapoYapo forestforest

The fruits are fleshy, fibrous cylindrical masses 33 to 4 cmcm inin diameterdiameter and coveredcovered withwith polygonalpolygonal honeycombhoneycomb pits.pits. Fruit-setting takes place inin October-November. ThereThere areare aboutabout 250250 fruits/kg.fruits/kg. - 86 -

The woodwood isis yellowyellow andand darkensdarkens slightlyslightly whenwhen exposedexposed toto light.light. It is semi-heavy (D12(D12 =~ 0.7)0.7) and of medium hardness (semi-hard);(semi-hard); its shrinkage andand nervosity are average. Its mechanical properties, durability and impregnability are good. ThanksThanks toto itsits goodgood mechanicalmechanical propertiesproperties andand goodgood natural durability (which(which cancan be enhanced by a preservative treatment) it is sought after asas timbertimber forfor outdooroutdoor usesuses (harbour{harbour works,works, railwayrailway sleepers),sleepers}, building (carpentry, floors, facings, indoor andand outdooroutdoor woodwork),woodwork), for slicing and forfor cabinet-making.cabinet- making. On young plantations, infestationinfestation with bud-bud­ boring caterpillars (Orygmophora(Orygmophora mediofoveata)mediofoveata) isis frequent,frequent, withoutwithout however seriously affectingaffecting thethe growthgrowth ofof thethe stands.stands.

SILVICULTURAL RULESRULES

The seeds must be sown early, 6 to 8 monthsmonths beforebefore plantingplanting out,out, asas thethe seedlings' growthgrowth isis oftenoften irregular.irregular. Because of thethe very smallsmall size of thethe seeds, they must bebe sownsown inin seedseed beds.beds. The seedlings are pricked out aboutabout a monthmont:_p- ·after germinationgermination began.began . This species is very easy to propagate by cuttiniS.cuttings.

The initialinitial recommendedrecommended plantplant densitydensity isis 11 100100 stemssterns perper hectare.hectare.

This isis aa fullfull sunlightsunlight speciesspecies withwith averageaverage growth.growth. At 11 yearyear thethe total mean height isis 1.21.2 toto 1.71.7 m,m, at 2 years it is 2.5 to 3.03.0 m, and at 4 years itit isis 66 toto 77 m.m.

The youngyoung saplingssaplings areare oftenoften multi-stemmed,multi-stemmed, andand thethe secondarysecondary stemsstems must be eliminatedeliminated inin thethe earlyearly yearsyears byby pruning.pruning.

The silviculturalsilvicultural rulesrules ofof thumbthumb areare asas follows:follows:

A first thinning atat thethe age of about 55 years reduces density toto 400/500 stems/ha.stems/ha. Before thinning, thethe mean height isis 11 to 13 m, the mean diameter isis around 10 cm and the basal area 6 to 8 m2/ha.m2 / ha.

The second thinningthinning atat thethe ageage ofof about 99 years reduces density to 200/250200/250 stems/ha.stems/ha. Before thinning, the mean height is 16 to 18 Tn,m, the mean diameter is 16 to 18 cm and the land areaarea is 9 toto 10 m2/ha.m2 / ha.

The third thinning is done when the trees are aboutabout 1515 yearsyears oldold and thethe basalbasal areaarea approximatelyapproximately 1212 m2/ha.m2/ha. One stemstem out ofof three is removed.removed . The mean diameter before thinningthinning is about 2525 CM.em.

The rotationrotation cyclecycle rangesranges fromfrom 3030 toto 4040 yearsyear s forfor an an exploitable exploitable diameter ofof 50SO cm.cm .

1.5 - Mahogany

Several different species belongingbelonging toto thethe KhayaKhaya genusgenus ( family) are grouped togethertogether underunder thethe namename "Mahogany":"Mahogany" :

Khaya ivorensis (Bassam mahogany),mahogany), a moistmoist evergreenevergreen forestforest species; - 87 -

VARIATION ININ MEANMEAN GIRTHGIRTH ASAS AA FUNCTIONFUNCTION OFOF AGEAGE ANDAND DENSITYDENSITY ININ THETHE MOIST EVERGREEN FOREST ZONE FOR BADI

200-300 stems/ha C (em)(cm)

60 C600-400 stemslha J

50

1000-700 stems/ha

40

30

20

10 INN- 10~---r----r---.---'----r---'----r---'----r--~----r---.------'~I 1 2IIIIIIIIIII 3 4 5 6 7 8 9g 10 11 12 Age (years) - 88 -

Khaya anthotheca (white mahogany), a transitional moist evergreen forest/moist semi-deciduous forestforest species;species;

Khaya grandifoliolagrandifoliola (broadleaved mahogany), a semi-deciduoussemi-deciduous forest and Sudanese gallery-forestgallery-forest species;species;

Khaya senegalensissenegalensis (bastard mahogany), a Sudano-GuineanSudano-Guinean andand Guinean species.species.

The MahoganiesMahoganies havehave aa veryvery extensiveextensive range.range . The bastard mahogany isis found from to Cameroon, CentralCentral Africa andand Uganda.Uganda. The ranges of the other Mahoganies correspondcorrespond roughlyroughly toto thethe moist semi-deciduous andand evergreen forest formations of West andand CentralCentral Africa.

The fruits areare globulousglobulous woodywoody capsulescapsules borne uprightupright onon toptop ofof thethe tree's crown.crown. Their diameter varies from one species to another: 4-7 emcm in the case of KhayaIChaya ivorensisivorensis and 6-10 emcm in thatthat ofof KhayaIChaya anthothecaanthotheca and grandifoliola. TheThe dehiscent fruits split into 4-5 superior valves joined together at thethe base.base.

The winged seedsseeds are ofof mediummedium sizesize (4 toto 5 cm long and 2 toto 33 cm wide). The main floweringflowering seasonseason extendsextends fromfrom AugustAugust toto DecemberDecember andand thethe corresponding fruit-settingfruit-setting runsruns fromfrom JanuaryJanuary toto April.April. The trees may fruit twice a year, with thethe secondsecond fruitingfruiting occurringoccurring inin July-September.July-September.

The bastard mahogany, which isis a savannah species, is a medium-sized tree 1515 to 2020 Mrri inin height,height/ frequently with aa sinuoussinuous bole.bole . The otherother Mahoganies are talltall treestrees thatthat reachreach aa height of 35-45 m, with conical crowns and foliage growing inin tufts.tufts. The bassam mahogany generally has a straightstraight trunk, whilst that of thethe whitewhite mahoganymahogany may be windingwinding andand hashas massivemassive buttressesbuttresses..

10 year-old standstand of Mahogany;MahoganYi Yapo forestforest - 89 --

The wood, which rangesranges in hue from pink to crimson, is soft (bassam(bassam mahogany) to semi-hardsemi-hard (broadleaved(broadleaved mahogany),mahogany), semi-heavysemi- heavy (012(D12 = 0.5 forfor bassam mahogany, 0.60.6 forfor whitewhite mahogany,mahogany, 0.70.7 forfor broadleavedbroadleaved mahogany).mahogany). ItsIts mechanical properties areare low (bassam mahogany)mahogany) to mediummedium (broadleaved mahogany and whitewhite mahogany).mahogany)

Durability isis mediummedium toto good,good, withwith lowlow impregnability.impregnability. TheThe woodwood isis easy to seasonseason andand toto work.work. Its technological characteristics makemake it aa highly desirabledesirable woodwood forfor cabinet-making,cabinet-making I slicingslicing, I veneering (peeling),(peeling) I furnishings, decoration andand joinery.joinery.

SILVICULTURAL RULESRULES FORFOR BASSAMBASSAM MAHOGANYMAHOGANY

The fruits areare sometimessometimes infestedinfested byby microlepidopteramicrolepidoptera caterpillarscaterpillars thatthat destroy thethe seeds.seeds.

The seeds are sownsown inin seed-bedsseed-beds and thethe seedlingsseedlings are pricked out in nursery beds forfor subsequentsubsequent plantingplanting whenwhen theythey reachreach thethe ageage ofof 11 oror 22 years,years, as saplings 1.21.2 toto 1.51.5 mm high.high.

Bagged plantsplan~s aa fewfew months'months I oldold areare anotheranother possibility.possibility.

The chiefchief constraintconstraint toto growinggrowing MahoganyMahogany isis thethe destructiondestruction ofof thethe terminal shoots byby thethe larvaelarvae ofof thethe microlepidopters HypsipylaHypsipyla robustarobusta and,and, to a lesser extent, Gyroptera robertsii, commonlycommonly knownknown asas "mahoganyIImahogany borers".borers II.

The destruction of the terminal bud causes the lateral buds to spurt into growth, with consequentconsequent forking.forking.

The time when thesethese attacksattacks occuroccur variesvaries fromfrom oneone standstand toto another.another. As aa generalgeneral rule,rule, they appear between the agesages ofof 1 andand 33 years.years. The infestation spreads very rapidly, and generally affects all treestrees agedaged 3-43-4 years. However, inin thesethese infestedinfested standsstands aa smallsmall number of well-shaped, fast-fast­ growing treestrees (6-8 mm high atat 4 years)years) can bebe observed.observed . The infestationinfestation heavily affects the trees'trees I growth up toto thethe ageage of 10-1510-15 years, after which their impact on growth tendstends toto decrease.decrease.

However, the casecase ofof thethe N'ZidaN1Zida plotplot (Cote(Cate d'Ivoire,d1rvoire, 1952), which suffered no attacks worthy ofof mention,mention, isis worthworth noting.noting.

As anan indication,indication, thethe followingfollowing values have been recordedrecorded onon somesome experimentalexperimental plots:

Health Silvicultural Age (years)(years) status parameters 11 2 3 4 5 10 15 19

Healthy Height (m)(m ) 8 10 24 plots Diameter (cm)(em) 30 42

Infested Height (m)(m) 11 2.22 . 2 3 3.5 4.5 10 plots Diameter (cm)(em) 15 28 - 9090 -

Stands of purepure MahoganyMahogany withwith nono cover,cover, of both high and lowlow stemstern density, are attackedattacked byby borersborers atat aa veryvery earlyearly age,age, oftenoften eveneven beforebefore thethe saplings are oneone yearyear old.old.

Two solutionssolutions can bebe envisagedenvisaged forfor thethe establishmentestablishment of MahoganyMahogany plantations:

- PlantationsPlantations sheltered by Leucaena leucocephala atat aa densitydensity ofof 700 stems/ha

In the year before planting, the Leucaena is sown in rows.rows. InIn thethe planting year,year, the Leucaena is cut backback beforebefore thethe MahoganyMahogany isis planted out.out. Until thethe saplings exceed the Leucaena'sLeucaena ' s height, the latter is regularly cut back or well thinned outout so asas to keepkeep the cover light.light.

The Mahogany trees are attacked when they emerge from the Leucaena cover (age(age 4/54 /5 years); their mean height is 4/54/5 m.m. LeucaenaLeucaena maintenance makesmakes itit possiblepossible toto keep adventitious vegetationvegetation underunder effective control.control.

The final density will bebe 70-8070-80 stems/hastems/ha with aa rotationrotation cyclecycle ofof approximately 40 yearsyears (exploitable(exploitable diameterdiameter 6060 cm).cm) . The average strong wood volume incrementincrement isis 6-86-8 m3/ha/year.m3/ha/year.

- Mixed plantations

Grown in association withwith speciesspecies whose initialinitial growth isis slowslow suchsuch as Niangon, OkouméOkoume oror Badi, a certain number of Mahogany stalks,stalks, inin spite of parasite attacks, grow sufficiently wellwell to ensure that they stay in the dominant storey and develop a buttlog lengthlength ofof about 1010 metres.metres .

The successsuccess of this typetype of mixedmixed plantation is the result ofof a compromise between:between:

on thethe oneone hand,hand, the relativelyrelatively slow growth of thethe borer-borer­ infested Mahogany trees;trees;

and on the other, the association with initially slow- growing species.species.

The silvicultural regimeregime appliedapplied isis toto growgrow MahoganyMahogany withwith otherother trees,trees, the aim being toto obtainobtain somesome well-shapedwell-shaped Mahogany treestrees inin the midstmidst ofof a stand wherewhere thethe otherother speciesspecies predominatespredominates (see the paragraph on mixedmixed stands).stands) .

There isis nono methodmethod ofof fightingfighting mahoganymahogany borersborers thatthat isis suitablesuitable forfor application on anan industrialindustrial scale.scale. ChemicalChemical treatmentstreatments (Methidathion)(Methidathion) areare only feasiblefeasible inin nurseries.nurseries.

Behaviour trials with variousvarious provenances ofof bassambassam mahoganymahogany havehave notnot revealed any interprovenanceinterprovenance differences withwith regard to susceptibility to borer attacks.attac·ks . - 91 -

At thethe presentpresent statestate ofo f knowledge,knowledge, thethe onlyonly feasiblefeasible solutionssolutions forfor Mahogany plantationsplantations areare thosethose describeddescribed above,above, butbut withwith nono realreal certaintycertainty ofof success.

1.6 - SipoSipo (Entandrophragma(En tandrophragma utile)uti/e)

The Sipo, which belongs to the MeliaceaeMeliaceae family, is aa gregarious,gregarious, half­half- shade, slow-growingslow-growing speciesspecies nativenative toto moistmoist semi-decidoussemi-decidous forests.forests.

In its naturalnatural range, annual rainfallrainfall variesvaries betweenbetween 11 400400 mmmm andand 22 500500 mm per year. The Sipo is found essentially inin CateCote d'Ivoire, Ghana,Ghana, Nigeria,Nigeria, Cameroon, thethe CentralCentral AfricanAfrican RepublicRepublic andand Congo.Congo.

The fruit is a capsulecapsule 18 to 28 cmem long and 5 toto 77 cmem wide,wide, with 55 thick valves and 55 or 6 seeds per compartment. The Sipo sets fruit once a year in February-March, andand thethe fruitfruit isis alwaysalways abundant.abundant.

The wood, of a pinkish-brownpinkish-brown colour, isis semi-heavy (D12(D12 == 0.6), fairly soft and shrinkage isis average.average. ItsIts mechanicalmechanical properties rangerange fromfrom poor toto average. Its naturalnatural durability isis average; itit is hard to impregnateimpregnate and easy to season. Sipo woodwood isis muchmuch sought-aftersought-after forfor indoorindoor andand outdooroutdoor woodwork,woodwork t cabinet-making, slicingslicing andand peeling.peeling.

The chiefchief problemproblem withwith SipoSipo plantationsplantations is, on somesome plots,plots, the w~theringwithering of thethe terminalterminal bud,bud t whichwhich stopsstops thethe growthgrowth ofof thethe mainmain stemstem andand isis accompanied by laterallateral branchingbranching andand thethe formationformation ofof aa broadbroad flatf lat crown.crown.

SILVICULTURAL RULES

In naturalnatural forest, thethe mean incrementincrement inin diameterdiameter remainsremains constantconstant upup to the age ofof 200200 yearsyears atat aboutabout 0.50.5 cm/year.em/year. The large-diameter natural forest trees that are traditionallytraditionally exploitedexploited forfor timbertimber areare oftenoften 300300 yearsyears old or more.more. In the case of treestrees withwith aa diameterdiameter ofof 60 cm,cm, the percentage of sapwoodsapwood rangesranges fromfrom 2020 percentpercent to 35 percent,percent t with an averageaverage ofof 28 percent.

The Sipo isis aa speciesspecies thatthat requiresrequires aa certaincertain amountamount ofof covercover whenwhen young.

The seeds are sownsown directlydirectly intointo potspots becausebecause ofof thethe fragilityfragility ofof thethe root system,system t which isis essentiallyessentially of thethe taproottaproot type.type. Particular care is needed in handling thethe plants.plants. Germination takestakes fromfrom 1515 daysdays toto 11 month.month.

The seedlings areare bedded outout between 6 weeks and 2 monthsmonths after sowing. It is imperative thatthat bedding-out bebe donedone before thethe seedlings'seedlings' taproot has had timetime toto developdevelop aa crook.crook. Treatment with auxinsauxins (AlB)(AIE) improves rootroot development.

The plantsp l ants subsequently remainremain inin thethe nursery bedsbeds forfor 11 or 22 years,years, depending uponupon when andand ifif theythey attainattain thethe dimensionsdimensions requiredrequired forfor planting-planting­ out, namely:namely :

- height between 8080 cmcm andand 11 m;m; - cocollarllar diameter betweenbetween 2.52.5 cmcm andand 3.53.5 cm,cm, - annual height increment at 1 year between 50 and 60 cm.cm. - 9292 -

The idealideal sapling forfor planting purposes is a 1-year-old rosette with a good root system.system . When trimmingtrimming thethe roots,roots, aa lengthlength ofof 3030 cm should be leftleft on the taproottaproot andand 1515 cmem onon thethe laterallateral roots.roots.

Stumping mustmust bebe avoided,avoided, as thethe taproottaproot systemsystem cannotcannot grow backback easily. The slow initialinitial growth rules out thethe useuse ofof small-sizedsmall-sized bagged plants inin favourfavour ofof carefullycarefully selectedselected largerlarger saplingssaplings growngrown inin nurseries.nurseries. Every care must be takentaken whenwhen rearingrearing the plants to make sure they do not develop crooks.crooks.

The initial growth-rate on plantations is slow: at 10 years,years, thethe meanmean height incrementincrement isis 0.80.8 toto 11 m/yearm/year andand thethe meanmean diameterdiameter incrementincrement forfor 100100 stems toto bebe grown toto maturitymaturity isis 11 toto 1.21.2 cm/year.em/year. Amongst these stems, about 30 stems/ha havehave aa diameterdiameter incrementincrement ofof 22 toto 2.52 . 5 cm/year.em/year.

In old stands a decrease inin the growth-rate cancan bebe noted.noted. At 30 years, the mean diameter incrementincrement drops to only 0.50.5 cm/yearcm/year with a meanmean heightheight increment of 0.50 . 5 m/year.m/year. The Sipo isis definitely aa slow-growingslow-growing species.species .

Sipo plantationsplantations involveinvolve considerableconsiderable problems.problems. This slow-growingslow-growing species requires from thethe secondsecond yearyear onwardsonwards aa progressivelyprogressively increasingincreasing exposure toto lightlight toto stimulatestimulate initialinitial growthgrowth (GOUDET(GOUDET -- WENCELIUS,WENCELIUS, 1974).1974).

As in thethe casecase of Mahogany, planting under cover of Leucaena sown in rows a year before thethe year inin which thethe SipoSipo saplingssaplings areare plantedplanted ensuresensures aa good recoveryrecovery raterate andand thethe satisfactorysatisfactory initialinitial growth of thisthis half-shadehalf-shade species whilst also'keepingalso' keeping regenerativeregenerative growthgrowth underunder control.control . The Leucaena plants shouldshould bebe cutcut backback forfor thethe firstfirst timetime beforebefore thethe secondsecond rainyrainy seasonseason and subsequently atat regularregular intervalsintervals untiluntil thethe SipoSipo crownscrowns breakbreak freefree ofof thethe regrowth.

On plantations, SipoSipo treestrees grow best in the moistmoist evergreenevergreen forestforest zonezone (Abbe,(Abbé, Anguededou,Anguédédou, Irobo: CoteC6te d'Ivoire) than in the semi-deciduous closed forest zone (Oumé,(Oume, Gregbeu:Gregbeu : CôteCote d'Ivoire).d'Ivoire).

1.7 - Ilomba (pycnanthus(Pycnanthus angolensis)

The Ilomba belongs toto thethe Myristicaceae family.family. It is found in moist forests fromfrom WestWest AfricaAfrica toto UgandaUganda andand Tanzania.Tanzania.

This tree is mainly toto be found inin scattered fashionfashion inin thethe secondarysecondary formations ofof evergreenevergreen andand semi-deciduoussemi-deciduous forests.forests . The boundaries of itsits natural rangerange correspondcorrespond toto aa minimumminimum annualannual rainfallrainfall of 1 300 mm and a dry season of lessless thanthan 66 months.months.

The oblong fruitfruit isis aa drupedrupe thatthat opensopens intointo twotwo fleshyfleshy valves.valves. It contains aa blackblack seedseed coveredcovered withwith aa pinkpink laciniatedlaciniated aril.aril . Flowering takestakes place inin September-NovemberSeptember-November andand fruitingfruiting inin January-February.January-February .

The white-colouredwhite-coloured wood isis lightlight (D12, 00.50),. 50), very soft,soft, of medium nervosity andand shrinkage.shrinkage. Its natural durability is low, but itit isis easyeasy toto impregnate. Its mechanicalmechanical properties are medium and it is easily machined. During seasoningseasoning thethe woodwood sometimessometimes warps.warps.

This soft, easily worked andand straight grained woodwood isis used for veneer­veneer- peeling, panels, furniturfurnitur~ frames, box-making andand minorminor joinery.joinery . - 93 -

TThehe young plantplant very rapidlyrapidly growsg rows a large taproott apr oot whose developmentdeve lopment mmustu s t be checkedchecked inin thethe nursery.nursery. CaCarer e must be takentake n toto avoidavoid cuttingcutting thethe taproot if itit isis large,large, becausebecause itsits destructiondestruction greatlygreatl y reducesreduces thethe plant'spl ant's rate ofof growth.growth. The useuse ofof stumpedstumped plantspl ants mustmust bebe avoided,avoided, in favour of seedlseedlingsi ngs inin largelarge bags.bags.

SSILVICULTURALILVI CULTURAL RULESRULES

The IlombaIlomba isis aa sun-lovingsun-loving speciesspecies with a mediummedium raterate ofof initialinitial growth. ItIt reachesreaches thethe heightheight ofof 0.50.5 mm atat oneone yearyear anda n d 3-43-4 mmat at 44 years,years, At the age of 10 years the average heightheight isis 12-1512-15 m,m, andand reachesreaches 20-2520-25 mm atat ageage twenty_twenty.

TheThe natural pruning of thisthis speciesspeci es isis inadequateinadequate and isis accompanied by the formation of large verticillate scar ridges. EEarlyarly artifartificiali cial pruning is therefore toto bebe recommended.recommended.

TheThe recommended plantingp l anting densitydensity is is 11 100100 stems/ha.stems/ ha . The first thinning should be carriedc arried outout whenwhen thethe treestrees areare aboutabout 7 years old toto reducereduce thethe density toto 300-350300 - 350 stems/ha.stems/ ha. Before thinning, the mean diameter isis aboutabout 15 cm.cm .

TowardToward the age ofof 1212 yearsyears aa secondsecond thinningthinning reduces density to 150- 200 stems/ha.stems/ ha . The mean pre-thinning diameterdiameter isis aroundaround 2020 cm.cm. When the trees areare aged a ged abouta b out 2020 a third and last thinning reduces density to 70-90 stemsstems/ha./ ha. The mean pre-thinning diameterdiameter isis 3030 cm.cm.

On good evergreen forest sites,sites, thethe exploitable diameter of 50SO cm is reachedreac hed around the age of 30 years and thatthat of 6060 cmcm towardtoward 4545 years.years. At age 15, the mean volumevolume incrementincrement isis 15 m3/ha/year.m3/ha/year . At ageage 30,30, it isi s 10 m3m3/ha/year/ ha/year (DUPUY,(DUPUY, 1983).1983).

1.8 - AzobeAzob6 (Lophira(Lophira alata)alata)

The Azobe,Azob6, a member of thethe OchnaceaeOchnaceae family,family, is an evergreen species native to the flatland moistmoist evergreen forestsforests (Guinea, Liberia, CoteCate d'Ivoire, Ghana, Cameroon,Cameroon, EquatorialEquatorial Guinea,Guinea, ...).. .. ) . Its range corresponds toto an annual rainfall exceedingexceeding 22 000000 mm/yearmm/year andand aa drydry seasonseason lastinglasting lessless thanthan 3 months. Under thethe lessless favourablefavourable ecologicalecological conditions ofof the semi-semi­ deciduous forests,forests, it is toto bebe foundfound inin thethe valleysvalleys andand alongalong thethe majormajor watercourses (Sangha,(Sangha, Oubangui,Oubangui, ...... ) ) wherewhere it maymay form almost pure stands.stands.

The fruit isis anan acheneachene withwith twotwo pinkpink wings.wings. The treestrees flowerflower fromfrom November toto JanuaryJanuary andand bearbear fruitfruit fromfrom JanuaryJanuary toto March.March. The root systemsystem of the young plants isis mixed (taproot/creeping(taproot/creeping roots).roots) .

The AzobeAzobé is a sun-loving,sun-loving, gregarious, medium growth-rate species that grows in secondarysecondary forests.forests. Like the Okoumé,Okoume, this gregariousgregarious species establishesestabli shes itself in clearedcleared forest.forest . It has been usedused sincesince 1926 for enrichment and reforestationreforestation operationsoperations forfor thethe productionproduction ofof fuelwoodfuelwood andand buildingbui lding timbertimber inin C6teCote d'Ivoire.d ' Ivoire . - 94 -

VARIATION IN GIRTH AS A FUNCTIONFUNCTION OF AGE AND DENSITYDENSITY FORFOR FRAMIREFRAMIRE UNDERUNDER AVERAGEAVERAGE FERTILITY CONCONDITIONSDITIONS

A

C (em)(cm)

150150

110000

50

I I I o lo10 20 3030 AgeAge (years)(years) - 95 --

9 year-oldyear-old AzohesiAzobés; Yapo forestforest

The brownish-red toto purplish-brownpurplish-brown wood isis veryvery heavyheavy (D12(D12 == 0.950.95 -- 1.1), very hard, withwith heavyheavy shrinkageshrinkage duringduring seasoningseasoning andand goodgood mechanicalmechanical properties. It is hardhard toto cutcut toto shapeshape andand hardhard toto impregnate,impregnate, butbut itsits natural durability isis remarkable.remarkable.

Its properties makemake itit anan excellentexcellent utilityutility woodwood (fuelwood,(fuelwood , stakes,stakes, postsposts...) ... ) and anan excellentexcellent timberwoodtimberwood forfor hydraulichydraulic usesuses (sluice gates,gates I harbour works,works, ...... ), ) I railwayrailway sleepers, mining works, etc.etc.

Traces of gall midgemidge attacksattacks havehave beenbeen observedobserved onon thethe leaves.leaves .

SILVICULTURAL RULESRULES

The mean height incrementincrement isis 1-1.51-1.5 mm upup toto thethe ageage ofof 15.15. At 66 yearsyears the mean height isis 6-86-8 m,m, andand 1212 years,years, 16-2016-20 m.m.

On single-species plantations, the mean diameter increment is 1-1.5 cm/yearem/year atat ageage 10.10.

In natural forest, the mean diameter increment ranges from 0.2 cm/year to 1 cm/year.em/year . For an exploitable diameterdiameter ofof 7070 m,m, thethe estimatedestimated ageage ofof thethe natural forestforest treestrees isis aboutabout 9090 years.years.

At 6-86 - 8 years, with a density ofo f 1 300 stems/ha,stems/ ha, the mean diameterdiameter is 8-10 em,cm, and thethe meanmean incrementincrement inin diameterdiameter isis 1-1.21-1.2 cm.cm. - 96 -

AtAt 1313 years, with a density of 400 stems/ha,stems/ha, the meanmean diameterdiameter is 13-1513-15 em,cm, with a mean incrementincrement ofof thethe orderorder ofo f 1.21.2 cm/year.em/year.

AtAt 1515 years,years, withwith a densitydensity of BOO800 stems/ha, 150 stems/ha have aa diameter exceeding 15 em.cm.

At 24 years, with aa density of 360 stems/ha, the mean diameter is 17 emcm and 100 stems/ha have aa diameterdiameter exceedingexceeding 2020 cm.em.

TheThe recommended plantation density is 11 1001 00 stems/ha with a firstfirst thinning around 66-8 - 8 years to reduce density to 500-600 stems/hastems/ha.. The thinning productsproducts can be sold as fuelwood.fuelwood. For an exploitable diameterdiameter ofof 6060 cm,em, the rotation cycle isis around 50 years.

1.9 - MakoreMakoré (Thieghemella heckelii)heckelii)

The MakoréMakore isis aa membermember ofof thethe SapotaceaeSapotaceae family.family. It is one ofof thethe largest ~oistmoist evergreen forestforest species,species, andand cancan attainattain aa diameterdiameter ofof 3 m and a height · of 50 m.

The MakoreMakoré flowers inin February-MarchFebruary-March andand itsits fruitsfruits ripenripen fromfrom AugustAugust to October.

The fruits are ovoidovoid andand large:large: 8 cmem long and 7 emcm in diameter. They contain two or threethree largelarge oilyoily seeds.seeds . These seedsseeds dodo notnot keepkeep well.well. They must be sown as soon as thethe fruitsfruits fallfall toto the ground, either inin nursery bedsbeds or by direct sowing.sowing . The seeds germinate very easily andand thethe seedlingsseedlings growgrow very rapidly inin thethe nursery.nursery. Given the large size ofof thethe seedsseeds (3(3 cmem xx 55 cm)em) and the rapid growth ofof thethe taproot,taproot, the plants must be grown in large-sized bags.

Plot of 9-year-old9-year-old MakoréMakore trees:trees : YapoYapo forest.forest. -- 9797 --

The wood is brownish-pink, of medium density (0.7),(0.7), and semi-hard. Its nervosity and shrinkageshrinkage areare medium,medium, andand itit isis of good durability. MakoreMakoré wood is much appreciated forfor veneering,veneering, outdooroutdoor joineryjoinery andand cabinet-making.cabinet-making.

SILVICULTURAL RULES

The MakoréMakore isis a sun-lovingsun-loving speciesspecies thatthat mustmust be planted in fullfull sunlight. TheThe useuse of a covercover plantplant suchsuch as PuerariaPueraria may be envisagedenvisaged to control adventitious vegetation.vegetation.

At the age ofof 11 year,year, thethe mean heightheight isis aroundaround 0.5/10.5/1 m;m; atat 33 years itit is 3 m. and at 77 years itit reachesreaches 1010 m.m.

The older plantationsplantations werewere plantedplanted underunder cover.cover. This in fact slowsslows their growth. At 10 years, thethe meanmean diameterdiameter isis 10-1210-12 cm.em. At 15 years, itit is 15-17 cmem and atat ageage 25,25, 2525 cm.em .

FForor plantations with no cover,cover, thethe mean diameterdiameter atat 1010 yearsyears isis 15-15- 1818 cm.

The recommended plantingplanting densitydensity isis 11 100100 stems/hastems/ha (3(3 mm xx 3 m), and the first thinning atat aroundaround 1010 years.years.

For anan exploitable diameter ofof 6060 cmem thethe rotationrotation cyclecycle isis somesome 60-8060-80 years.

2. - MEDIUM-ROTATION SPECIESSPECIES

2.1 -- FramiréFramire (Terminalia(Terrninalia ivorensis)ivorensis)

The FramiréFramire belongsbelongs toto thethe CombretaceaeCombretaceae family.family. Its range extendsextends continuously fromfrom Guinea toto WestWest Cameroon.Cameroon.

It isis aa transitionaltransitional moistmoist evergreenevergreen forest/moistforest/moist semi-deciduous forestforest species. Its range, thanks to forestforest clearances,clearances, tends toto expandexpand intointo thethe moist evergreenevergreen forestforest zone.zone. The boundaries of thisthis sun-lovingsun-loving deciduousdeciduous species correspond toto aa rainfallrainfall ofof lessless thanthan 11 300300 mm/yearmm/year andand aa drydry seasonseason exceeding 4-5 months.months. It grows up toto an altitude ofof 11 200200 mm (Cameroon).(Cameroon).

The fruitfruit isis anan ellipticalelliptical samarasamara measuring 6 to 7 cm in length and 2 cm in width. Flowering beginsbegins inin AprilApril afterafter thethe newnew leavesleaves havehave begunbegun toto appear, and lastslasts untiluntil June.June. The interval between the opening of thethe leafleaf buds andand floweringflowering isis 3-43-4 weeks.weeks. The flowersflowers areare fertilizedfertilized byby insectsinsects (lepidoptera and diptera).diptera) Fruiting, which begins inin December,December, isis abundantabundant from January toto March.March.

In the case ofof naturalnatural forestforest trees,trees, thethe woodwood isis lightlight (D12 -= 0.5), soft, with low shrinkage andand medium nervosity.nervosity. Its transversal cohesiveness is poor and its axialaxial cohesivenesscohesiveness isis average.average. Both natural durability and impregnability areare average.average. The wood is easily seasoned.seasoned.

The chief uses of thisthis wood are building (indoor(indoor and outdoor woodwork, timberwork), the panelling industryindustry (plywoods(plywoods andand coreboards)coreboards) andand cabinet-cabinet­ making. - 98 --

The Framir6Framire startsstarts bearingbearing fruitfruit atat 5-65-6 years.years. One kilokilo ofof seedsseeds contains approximately 55 000 winged seedsseeds oror 1010 000000 de-wingedde-winged seeds.seeds. To arouse the seeds from their original dormant state (which(which is probabprobablyl y due to the integument), thethe seedsseeds shouldshould bebe soakedsoaked inin coldcold waterwater forfor 22 days.days.

For planting purposes, thethe useuse ofof bagged plantsplants isis preferable toto thatthat of stumped plants.plants . Cutting the seedling'sseedling ' s rootroot system,system, which isis basically ofof the taproot type,type, prior to planting willwill in fact alteralter itsits subsequentsubsequent growthgrowth by favouring the development ofof creeping roots.roots. Moreover, stumpedstumped plants growgrow at a slower raterate thanthan baggedbagged plants.plants.

The seeds are frequently attacked by two CurculionidaeCurculionidae (Nanophyes(Nánophyes spp. and Auletobius kuntzeni) which can considerably reduce the germination rate.rate.

On saplings,saplings, the leaves and young shootsshoots are subjectsubject toto attackattack byby numerous speciesspecies (Coleoptera, Lepidoptera, Orthoptera)Orthoptera) whichwhich cancan lead toto withering ofof thethe crown.crown.

On older plantations thethe followingfollowing havehave beenbeen observed:observed:

defoliation by Notodontidae caterpillars (defoliating caterpillars);caterpillars) ;

nibbling of the trunk byby ColeopteraColeoptera (Cerambycidae, Bostrychidae) and LepidopteraLepidoptera (Cossidae,(Cossidae, Megalopygidae);Megalopygidae);

symPtomssymptoms of root-rotroot-rot (Armillaria)(Armillaria) havehave alsoalso beenbeen occasionallyoccasionally reported onon somesome trees.trees.

If no thinnings are carried out the surplus-dominated trees, after a phase ofof arrestedarrested growthgrowth lastinglasting severalseveral years,years, graduallygradually diedie offoff throughthrough aa wasting process characterizedcharacterized byby aa droopingdrooping toptop followedfollowed byby thethe witheringwithering ofof the crown and by secondarysecondary attacks by insectsinsects (scolytids and cerambycidae)cerambycidae) and pathogenicpatho:g.enic fungi.fungi.

Detailed study of this wasting process has revealed abnormalities in the cycle of mineral andand organicorganic (nitrogen)(nitrogen) elementselements andand alsoalso alterationsalterations inin the nutritional balancebalance inin thethe witheringwithering treestrees onon plantations.plantations. Incidentally, when thethe decompositiondecomposition ofof FramiréFramire rootsroots in thethe soil was studiedstudied inin a controlled environment,environment, it was found thatthat the latter havehave a markedlymarkedly depressive effecteffect onon thethe growthgrowth andand nitrogennitrogen uptakeuptake ofof youngyoung plantsplants (MALLET,(MALLET, ~979)1979). .

Lastly, the FramiréFramire happens to be veryvery sensitivesensitive toto waterwater supplysupply stress. On marginal sitessites withwith anan unbalancedunbalanced waterwater supplysupply oror afterafter aa runningrunning fire has passed, withering phenomenaphenomena cancan alsoalso bebe observedobserved inin standingstanding trees.trees.

These findings show thatthat thisthis suddensudden witheringwithering isis linked to thethe frequently combinedcombined actionaction of:of:

unfavourable environmentalenvironmental factorsfactors (site, water deficiency,deficiency, fires ...)... )

stress from intense competition

disturbed nutritionalnutritional balance.balance. - 99 -

Base of a 25-year-old25-year-old Framir6;Framire; YapoYap a forestforest

SILVICULTURAL RULESRULES

The recommended plantingplanting densitydensity isis 700700 stems/ha.stems/ha . I The Framir6Framire isis aa speciesspecies withwith averageaverage initialinitial growth:~owth: atat 11 yearyear thethe mean height isis 2/2.52/2.5 m,m, atat 22 yearsyears itit isis 5/65/6 m,m, atat 33 yearsyears itit isis 9/109/ 10 mm andand at 4 years itit reachesreaches 12/1412/14 m.m.

Analysis of height increments revealsreveals thatthat at 15 years the greatergreater partpart of suchsuch growth hashas alreadyalready beenbeen achieved,achieved, andand thethe finalfinal harvestharvest standstand mustmust already bebe established.established. The recommendedrecommended thinningthinning scheduleschedule forfor plantationsplantations grown without covercover isis asas follows:follows:

First thinning:thinning:

Should start as soon as thethe dominant height reachesreaches 1111 m;mj one stemstem out of twotwo shouldshould bebe removed.removed.

Second thinning:thinning:

Reduces the density to 175 stems/ha;stems/ha; beforebefore thinning,thinning, the meanmean diameterdiameter is 20 emcm and the basal areaarea 1111 m2/ha.m2/ha.

ThThirdi rd thinning:thinning:

Brings the densitydensity downdown toto 7070 stems/ha;stems/ha; beforebefore thinning,thinning, the mean diameter isis 4040 cmem andand thethe basalbasal areaarea 1212 m2/ha.m2/ha. - 100 -

A provisionalprovisional yieldyield tabletable isis availableavailable forfor FramireFramire (DUPUY(DUPUY etet al.,ai., 1989). There areare fourfour sitesite classes.classes. TheThe lastlast thinningthinning isis optional, dependingdepending upon the target diameter.diameter .

Site classes 1 2 3 4

Exploitable diameterdiameter (cm)(em) 45 44 43 42 50 48 46 45

Number ofof thinningsthinnings 3 3 3 3 4 4 4 4

Exploitable ageage (years)(years) 22 27 32 37 27 32 4040 60

Two targetstargets havehave beenbeen retainedretained withwith regardregard toto exploitableexploitable diameter:diameter: 40 andand 4545 em.cm. The followingfollowing tablestables indicateindicate thethe characteristicscharacteristics of thethe corresponding stands.stands.

HARVEST CHARACTERISTICSCHARACTERISTICS AT THINNINGSTHINNINGS ANDAND FINALFINAL FELLINGFELLING

Target exploitable Site classes diame'terdiameter 40-45 cmem 1 2 3 4

First thinning

Age (years)(years) 3 4 5 6 Number of stems/ha harvested 361 361 361 361 Harvest volume (m3/ha)(m3/ha) (25) (25(25) ) (25) (25)

Second thinning

Age (years)(years) 6 7 8 9 Number of stems/ha harvest 175 175 175 175 Harvest volume (m3/ha)(m3/ha) 36 44 51 58 Mean diameter 17 19 20 21

Third thinning

Age (years)(years) 11 12 13 15 Number of stems/hasterns / ha harvested 85 85 80 80 Harvest volume (m3/ha)(m3 / ha) 47 47 45 51 Mean diameter (cm)(em) 26 26 26 27

FinalFinal harvest

Age (years)(years) 22 27 32 37 Number of stems/hastems/ ha harvested 90 90 95 95 HarvestHarvest volume (m3/ha)(m3 / ha) 228 220 214 204 Mean diameter (cm)(em) 45 44 43 42

Total volume produced (m3/ha)(m3/ha) 336 336 335 338 MeanMean increment (m3/ha/year)(m3 / ha/ year) 15.3 12.412 . 4 10.55 9.1 - 101 -

HARVEST CHARACTERISTCSCHARACTERISTCS AT THINNINGS AND FINAL FELLING

Target exploitableexploitable Site classesclasses diameter 45-50 cmem 1 2 3 4

First thinning

Age (years)(years) 3 4 5 6 Number of stems/hastems/ha harvestedharvested 361 361 361 361 Harvest volumevolume (m3/ha)(m3/ha) (25) (25)(25 ) (25)(25 ) (25)

Second thinning

Age (years)(years) 6 7 8 9 Number of stems/hastems/ha harvest 175 175 175 1751 75 Harvest volumevolume (m3/ha)(m3/ha) 36 44 51 58 Mean diameter (cm)(em) 17 19 20 21

Third thinning

Age (years)(years) 11 12 13 15 Number of stems/ha harvested 80 80 75 75 Harvest volumevolume (m3/ha)(m3/ha) 44 44 42 48 "Mean diameter (cm)(em) 26 26 26 27

Fourth thinning

Age (years)(years) 17 20 24 27 Number of stems/ha harvested 30 25 25 25 Harvest volume (m3/ha)(m3/ha) 37 31 31 33 Mean diameter (cm)(em) 34 34 34 34

Final harvest

Age (years)(years) 27 32 40 50 Number ofof stems/hastems/ha harvestedharvested 65 70 75 75 Harvest volume (m3/ha)(m3/ha) 214 204 200 188 Mean diameterdiameter (cm)(em) 50 48 44 45

Total volume producedproduced (m3/ha)(m3/ha) 356 349 350 352 Mean incrementincrement (m3/ha/year)(m3/ha/year) 1313.2 .2 10.9 8.8 7.0

For anan exploitableexploitable diameter of 40-45 em,cm, three thinnings areare necessarynecessary and the exploitable ageage isis approximatelyapproximately 3030 years.years.

For an exploitable diameter of 45-50 em,cm, four thinnings arenecessaryarenecessary and the exploitable ageage isis approximatelyapproximately 4040 years.years.

The mean increment in strong wood volumevolume ranges from 7 to 15 m3/ha/year. - 102 -

2.2 - FrakeFraké (Terminalia(Terminalia superba)

The Fraké,Frake, whichwhich belongsbelongs toto thethe Combretaceaecombretaceae family,family, is a deciduousdeciduous sun-loving species nativenative toto thethe moist semi-deciduous forest.forest. In its naturalnatural range, the annual rainfallrainfall isis 11 000000 mm/year toto 11 800 mm/year; very locallylocally itit may be as high as 2 500 or even 3 000000 mm/yearmm/year (Cameroon, Gabon). The duration of the dry season isis 33 toto 55 months.months. The FrakéFrake is found at altitudesaltitudes betweenbetween 150 and 600600 m.m.

The leaves are shedshed inin November-February;November-February; mostmost trees havehave growngrown newnew leaves before thethe endend ofof thethe drydry season.season.

The dates of refoliationrefaliation andand flowering are closely correlated:correlated: flowering, which lastslasts forfor 22 toto 55 weeks, takestakes place either asas thethe new leavesleaves are appearingappearing oror immediatelyimmediately afterwards.afterwards. "The process ofof defoliation-defoliation­ refaliationrefoliation gives riserise toto thethe appearanceappearance ofof flowers,flowers, doubtlesslydoubtlessly asas aa resultresult of some stimulistimuli such as, for example,example, the auxinsauxins synthesiedsynthesied as buddingbudding occurs"occurs" (BOUILLET 1984) 1984). .

The duration ofof fruitingfruiting isis variable:variable: fromfrom 66 toto 99 months. The fruits,fruits, which are winged samaras, develop during the rainy season andand reachreach maturitymaturity at the beginning ofof thethe followingfollowing drydry season.season . The trees thatthat bearbear thethe mostmost flowers areare often 2525 yearsyears oldold oror more.more. There are approximatelyapproximately 1010 000000 wingless seeds per kg.kg.

This isis a species~pecies thatthat can be easily propagated byby grafts andand cuttings.cuttings. The root system isis basically ofof thethe taproot typetype inin young plants, but rapidly develops into aa creepingcreeping rootroot systemsystem withwith numerousnumerous secondarysecondary roots.roots.

In the natural forestforest trees,trees, thethe white-coloured woodwood isis softsoft toto semi-semi­ hard, light (D 12 12 = = 0 0.5. 5 -- 0.6), with low nervosity andand lowlow shrinkage.shrinkage. It isis used forfor indoorindoor andand outdooroutdoor joinery,joinery, veneer-peeling,veneer-peeling, slicing, plywood and interior decorating.

Its mechanical properties are medium to poor: its transversal cohesiveness is poor andand itsits axialaxial cohesivenesscohesiveness isis medium.medium. Its naturalnatural durability is poor. SeasoningSeasoning andand impregnationimpregnation areare easy.easy.

The density of plantationplantation wood is lessless thanthan thatthat ofof naturalnatural forestforest woodwood..

As regards natural pruning, which is oftenoften imperfect,imperfect, the prunedpruned heightheight at aa givengiven ageage andand forfor a given totaltotal height variesvaries accordingaccording to the provenance. At age 12, with the same totaltotal heightheight ofof 22 m, the pruned height varies from 10 to 15 m depending upon thethe provenance.provenance.

FrakeFrak6 trees also show interprovenance variability with regard to early shedding of leaves, earlyearly sheddingshedding beingbeing negativelynegatively correlatedcorrelated withwith vigour.vigour. - 103103 -

VARIATION ININ MEAN GIRTHGIRTH ASAS AA FUNCTIONFUNCTION OFOF AGEAGE ANDAND DENSITYDENSITY FORFOR FRAKEFRAKE UNDERUNDER AVERAGEAVERAGE FERTILITYFERTILITY CONDITIONS

c (em)

150

C165 s1emsiha ) 100

C325 S1emslha)

50

C711 S1emslha)

5 10 15 20 25 Age (years) - 104 -

The best provenances are GregbeuGregbeu (Cate(Cote d'Ivoire),d'Ivoire), AbofourAhofour andand AmentiaAmentia (Ghana), andand MMTBalmayo'Balmayo (Cameroon).(Cameroon) . Introduction trials with LimbaLimba provenancesprovenances native to thethe SouthernSouthern hemispherehemisphere provedproved disappointing.disappointing.

The chief phytopathology problemsproblems encounteredencountered are:are:

internal black spottingspotting causedcaused byby DoliopygusDoliopygus spp.spp .

infestation by defoliating caterpillars (Lasiocampides, Lymantriides and Saturnides) and grasshoppers (Zoonocerus variegatus) which destroy the leaves or the terminal shoots.shoots.

internal pocketspockets ofof black rotrot duedue toto injuriesinjuries oror defectivedefective naturalnatural pruning. In particular, thethe presencepresence ofof arborealarboreal ants' ants' nests at thethe levellevel ofof thethe verticilsverticils can bebe aa contributingcontributing factor.

infestation by cossidae (Eulophonotus spp.spp.)) at the level of the verticils and pruning stumps.stumps.

SILVICULTURAL RULES

A yieldyield tabletable isis availableavailable forfor thethe FrakéFrake (DUPUY(DUPUY etet al.al . 1987).1987).

The recommended planting densitydensity is 711 stemsstems/ha./ ha. Frake is a fast-fast­ growing deciduous.species:deciduous species: the mean total height increment atat age 44 is 2.5 m/year,m/ year, andand 22 m/year m/ year atat ageage 10.10.

On sitessites of averageaverage fertility,fertility, thethe rotationrotation cycle isis 20-2520-25 years forfor an exploitable diameterdiameter ofof 45-5045-50 cm.em.

The recommended thinningthinning scheduleschedule isis basedbased onon threethree operations:operations:

First thinning: WhenWhen thethe dominantdominant heightheight reachesreaches 1010 m,m, andand oneone stemstem outout of twotwo isis removed.removed.

Second thinning: When the dominant height reaches 15 m and the basal area 1010 m2/ha.m2/ha. Before thinning,thinning, thethe meanmean diameterdiameter isis approximatelyapproximately 2020 cm.cm. The thinningthinning raterate isis oneone stemstem outout ofof two.two.

Third thinning: When thethe dominantdominant heightheight reaches 2020 m andand thethe basalbasal area 10-11 m2/ha.m2 / ha . Before thinning, thethe mean diameter isis 28 cm. Approximately one treetree out ofof threethree isis thinned.thinned . - 105105 -

The thinning schedule dependsdepe nds onon sitsitee fertilityfertility.. FiveFiv e ssitei te cclasseslasses havhavee bbeeneen envisaged: e nvisaged :

SSiteite classclass 5 4 3 2 1

FFertilityertility BadBad PPooroor MediumMediu m Good VeVeryry GoodGood

FFirstirst thinningth inning

NaveN ave (stems/ha)(stemslha) 711711 771111 771111 711711 711711 Ne (stems/ha)(stems/ha) 36136 1 363611 386 401401 4114 11 Age (years)(years) 7 6 5 4 3

SecoSecondnd thinninthinningg

NaveN ave (stems/ha)(stemsfha) 350 350 325 310 300 Ne (stems/ha)(stems/ha) 165 175 160 150 150 Age (years)(years) 10 9 8 7 6

Third thinningth inning

NNa aveve (stems/ha)(stems/ha) 185185 175 165 116060 150150 Ne (s(stems/ha)temslha) 55 60 65 65 60 Age (years)(years) 16 1414 1122 1111 9

HarvestHarv Clli

N (stems/ha)(stems/ha) 130130 115 110000 95 90 Age (years)(years) 25 2244 23 20 1818 MeanMean diameterdiameter (cm)(em) 35 4400 45 47

MerchantableMerchantable volumevolume (diameter(diameter > 7cm)7cm) 116565 119797 226 233 246 standingstanding at cycle end (m3/ha)(m3/ha)

TotalTotal productionproduction atat 241241 228686 33133 1 346 348 cyclecycle end (m3/ha)(m3 /ha)

Mean incrementincrement at cyclecycle endend 9.6 11.11.99 114.44.4 117.37.3 19.319.3 (m3/ha/year)(m3/halyear)

NavN avee == NumberNumbe rof of stems/ha stems/ha before before thinningth inning NteNte = NumberNu mber ofof stems/ha Slems/ha harvested harvested during during thinningthinning

TheThe suggested provisionalp r ovi sional yieldy i eld tabletable isis characterizedcharacterized byby aa seriesseries ofof eaearlyrly andand energeticenergeti c thinnings.t h innings. The forestf orest managemanagerr intervenes i ntervenes asas soon as possiblepossi bl e to trytry toto preventpreven t thethe developmentdevel opment of aa statestate ofof competitionc ompetition thatthat wowoulduld bbee ddetrimentale trimental toto thet he individualindivi dua l growthgrowth ofof thethe treest rees scheduledscheduled toto reachreach maturity.maturit y .

The thinningt h i nning ratesrates are,a r e , incidentally,inc ide ntally, dimensionedd i men s i one d soso asas toto reducereduce thet he nnumberumbe r of o f operationsoperati o ns withoutwithout compromisingcomp romising the futurefutur e ofof the standsstands in quesquestion.t ion . As a generalgeneral rule,rul e, thethe youngeryounger thet he standstand andand thethe betterbetter itsi ts site,s i te, the higherhigher the thinningthinni ng raterate willwi ll be.be . - 106 -

FrakeFrak6 after first thinning; Mopri forest

The object is toto ensureensure thatthat thethe thinningsthinnings are carried outout in the dynamic phase of the stand'sstands establishment,establishment, thisthis beingbeing thethe periodperiod duringduring whichwhich the trees respond most successfullysuccessfully and rapidly to changes in environmental conditions.

The stand isis thusthus brought toto itsits finalfinal density at an early age and can thus enjoy a maturing periodperiod ofof aboutabout tenten yearsyears beforebefore thethe finalfinal harvest.harvest.

The option ofof aa moremore staggeredstaggered thinningthinning scheduleschedule whichwhich couldcould allowallow intermediate harvests ofof medium-sizedmedium-sized productsproducts hashas notnot beenbeen pursued.pursued. This would inin fact,fact I resultresult inin aa longerlonger rotationrotation cycle;cycle; on thethe otherother handhand thethe marketing prospects forfor thinningthinning productsproducts areare veryvery uncertain.uncertain.

The felling cycle for thinning is in factfact veryvery shortshort:: intervals of 3-4 yearsyears on fertile sites,sites, andand upup toto 66 yearsyears onon aa badbad site.site. The choice ofof rotation cycle lengthlength isis determineddetermined inin relationrelation toto exploitableexploitable diameter,diameter, which ranges fromfrom 3535 cmcm on the least fertile sitessites toto 5050 cm on the best sites. Consequently, the lengthlength ofof thethe recommendedrecommended rotationrotation cyclecycle nevernever exceedsexceeds 25 years, even inin thethe casecase ofof standsstands withwith poorpoor ratesrates ofof growth.growth.

Under average conditions,conditions, the final harvest represents around 70 percent of the totaltotal production. This final harvest amounts toto - 107107 --

200-250 m3/ha m3/ha (mainstem volume),volume), with a bolebol e volume of approximatelyapproximatel y 170-230170-230 m3/ha.m3/ha. ThThisi s corresponds to a cyccycle-endl e-end mean increment of 8-13 m3/ha/year (standing(standing volumevolume ofof thet h e mainmain stem).stem) .

2.3 - Samba (Triplochyton(Triplochyton scleroxylon)scleroxylon)

The SambaSamba belongsbelongs toto thethe SterculiaceaeStercul iaceae family.fami ly. It isis aa deciduousdeci duou s species native to semi-deciduous closed moist forests. ClearingClearing is affordingaffording this species thethe opportunity toto taketake hold in the moist evergreen forest zone as well.

IInn its naturanaturall range, thethe annual rainfallrai nfall varies betweenbetween 11 100100 mmmm andand 1 800 mm per year and thethe drydry seasonseason lastslasts fromfrom 33 toto 55 months.months.

Flowering startsstarts inin NovemberNovember andand fruit-settingfruit-setting followsfollows inin February-February­ March. IItt is veryvery irregular; moreover, thethe fruits are very often parasitparasitizedi zed by,by: fungi (Mycosyrinx(Mycosyrinx nonveilleri) that cause lethal malformations in the floral organsorgans andand fruits,fruits,

or weevils (Apion(Apion spp.)spp.) thatthat attackattack thethe fruits.fruits.

Furthermore, when thethe seeds are harvested care must bebe taken to avoidavoid drying them too suddenly; thethe drying process must be very gradual,gradual, otherwotherwisei se the seeds'seeds' germinativegerminative abilityability decreasesdecreases sharply.sharply. There are approximatelyapproximatel y 5 000 wingless seeds to thethe kilo.kilo. To makemake upup forfor thethe Samba'sSamba's irregularirregul ar fructification, reforestation operators rely on large-scale vegetativevegetative propagation byby herbaceousherbaceous cuttingscuttings (DELAUNAY(DELAUNAY 1978).1978) .

The implementation ofof thisthis techniquetechnique isis basedbased onon aa regularlyregularly cut-backcut-back wood supplysupply areaarea thatthat providesprovides thethe leafyleafy herbaceousherbaceous shootsshoots whichwhich willwil l bebe planted under framesframes (see(see nurserynursery techniques).techniques) .

The root system consists of aa taproot,taproot, frequentlyfrequent l y forked, with a · fewfew secondary roots.roots.

The wood is yellowish-white inin colour,colour, lowlow isis densitydensity (D(D 1212 == 0.4)0.4) andand in hardness,hardness, shrinkage andand nervosity;nervositYi itit isis easy to season and to impregnate. IItsts physicalphysical properties makemake itit aa goodgood woodwood forfor sawing,sawing, slicingsli cing andand peeling.peel ing. Its mechanical properties (low(low axialaxial andand transversaltran sversal cohesiveness)cohesiveness) andand lowl ow durability restrict its use to furniture,furniture, indoor woodwork and the panellingpanell ing industry.

The logslogs oftenoften showshow spotsspots andand discolorationsdiscol orations duedue toto thethe SambaSamba bark-bark­ beetle (Trachyostus(Trachyostus ghanaensis).ghanaensis). In addition,addition, the Samba is also subject toto cossidae attacksattacks (Eu]ophonotus(Eulophonotus spp.), whichwhich can involve a large number of trees. Luckily, this isis generally limitedlimited toto thethe buttwood,buttwood, upup toto aa heightheight ofof 2-3 metres.

Attacks by NotodontidNotodontid caterpillars (Anaphe(Anaphe venavenata)ta) knownknown in Nigeria asas a major defoliation agent,agent, havehave alsoalso beenbeen recorded.recorded. -- 108 -

17-year-old Samba trees, Mopri forest

SILVICULTURAL RULESRULES

The Samba isis aa speciesspecies withwith fastfast diameterdiameter growth. The mean incrementincrement ranges from 11 cm/yearem/year toto 33 cm/year,em/year, dependingdepending onon thethe ageage andand typetype ofof stand.stand. The SambaSamba isis aa sun-lovingsun-loving speciesspecies thatthat mustmust bebe plantedplanted withoutwithout covercover toto express its fullfull potential.potential.

The recommended plantingplanting densitydensity isis 700700 stems/ha.stems/ha.

In relation toto the planting method optionsoptions (undergrowth(undergrowth andand nono cover),cover) f two separate yield tablestables havehave beenbeen drawndrawn upup (DUPUY(DUPUY etet al.al. 1990).1990).

No cover method

The exploitable diameter ranges fromfrom 3535 cmem toto 6060 cm,em, dependingdepending uponupon site fertility. The proposed silvicultural optionsoptions havehave beenbeen proportioned soso as toto avoidavoid excessivelyexcessively longlong rotationrotation cycles.cycles . The foreseenforeseen exploitableexploitable diameter varies inin relationrelation toto fertility.fertility.

Thinning isis heavyheavy andand carriedcarried outout earlyearly onon inin thethe cyclecycle so as to bring the stands to their finalfinal densitydensity asas soonsoon asas possible.possible.

The exploitable agesages rangerange fromfrom 1818 toto 4040 years.years.

The mean yolumevolume incrementincrement isis betweenbetween 55 andand 1818 m3/ha/year.m3/ha/year. - 109 -

VARIATION ININ MEAN GIRTH AS A FUNCTION OF AGEAGE ANDAND DENSITYDENSITY FORFOR SAMBASAMBA

C (em)(cm)

150

100

50

5 10 15 20 25 30 Age (years) - 110 --

SILVICULTURE RECRECOMMENDATIONSOMMENDATIONS AND PRODUCTIVITY DATADATA FORFOR SAMBA PLANTED WITH NO COVER

Harvestability Mean increment Site Number of Age Dg V Final TTotalotal classes thinnings (years) (em)(cm) (m3/ha) harvest harvest (m3/ha/yr)(m3/ha/yr)

1 4 1188 60 209 17.17.88 11.11.6 6

2 3 24 50 263 14.3 10.9

3 3 30 45 237 10.4 7.9

4 - 3 35 40 184 7.7 5.2 ' .:. 5 3 40 35 138138 5.5 3.4

It isis usefuluseful toto taketake intointo accountaccount thethe influenceinfluence ofof thinningthinning on thethe vovolumeslumes harvested. For this purpose, fourfour cutscuts cancan bebe envisaged.envisaged.

The resulresultst s are given for the five site classes taken into coconsiderationnsideration forfor thisthis yieldyield table.table.

SSitei te classc lass 5 4 3 2 1 Fertility Bad PoorPoor Medium Good V. Good First thinningthinning NaveN ave (stems/ha)(stems/ ha) 711 711 711 711 711 N e (ste(stems/ha)ms / ha) 363611 363611 386 401 411 Age (years) 7 6 5 4 3 Second thinning NaveN ave (stems/ha)(stems/ ha) 353500 350 325 310 300 N e (s(stems/ha)tems/ ha) 165 171755 160 150 150 Age (yea(years)rs) 10 9 8 7 6 ThirdThird thinning NaveN ave (stems/ha)(stems/ha) 185 171755 165 160 150 N e e (stems/ha) 55 60 65 65 60 Age (ye(years)ars ) 16 14 1122 11 9 HarvestHarvest N (stems/ha) 130l30 115 100 95 90 Age (years) 2525 24 23 20 18 Mean diameterdiameter (cm)(em) 35 40 4455 47 49 Standing volume of the main stem at 165 197197 226 233 246 cycle endend (m3/ha)(m3/ha) TotTotalal production atat cycle end (m3/ha)(m3/ha) 241 286 331 346 348 Mean incrementincrement at cycleeyele endend (m3/ha/year)(m3/ha/year) 9.6 11.11.9 9 14.4 1717.3.3 119.39.3 - 111 -

The suggested provisionalprovisional yieldyield tabletable isis characterizedcharacterized byby aa seriesseries ofof early and energeticenergetic thinnings.thinnings . The forest manager intervenesintervenes as soon as possible to trytry toto preventprevent thethe developmentdevelopment ofof aa statestate ofof competitioncompetition thatthat would be detrimental toto thethe individualindividual growthgrowth ofof thethe treestrees scheduledscheduled toto reachreach maturity.

The thinning ratesrates are,are, incidentally,incidentally, dimensioneddimensioned soso asas toto reducereduce thethe number ofof operationsoperations withoutwithout compromising thethe future of the standsstands in question. As a general rule,rule, thethe youngeryounger thethe standstand andand thethe betterbetter itsits site,site, the higher the thinningthinning raterate willwill be.be .

The objectobj ect isis toto ensureensure thatthat thethe thinningsthinnings areare carriedcarried out inin thethe dynamic phase ofof the stand'sstand r 5 establishment,establishment, thisthis beingbeing thethe period during whichwhich the trees respond most successfullysuccessfully andand rapidlyrapidly toto changeschanges inin environmentalenvironmental conditions.

The stand isis thusthus broughtbrought toto itsits finalfinal densitydensity atat anan earlyearl y ageage and cancan thus enjoy aa maturingmaturing periodperiod ofof aboutabout tenten yearsyears beforebefore thethe finalfinal harvest.harvest .

A moremore staggeredstaggered thinningthinning scheduleschedule whichwhich couldcould allowallow intermediateintermediate harvests of medium-sized productsproducts hashas notnot beenbeen considered.considered. It would inin fact,fact, result in aa longer rotationrotation cycle;cyclei on thethe otherother hand,hand, the marketingmarketing prospects forfor thinningthinning productsproducts areare veryvery uncertain.uncertain.

The fellingfelling cyclecycle foreseenforeseen forfor thethe thinningsthinnings isis inin factfact short.short. It foreseesf.oresees intervalsinterval s of 3-43-4 years on fertile sites, and up to 6 yearsyears onon aa badbad site. The choicechoice ofof rotationr otation cyclecycle lengthlength isis determineddetermined inin relationrelation toto exploitable diameter. ThisThis diameterdiameter rangesranges fromfrom 3535 cmcm onon thethe leastleast fertilefertile sites to 50 cm on the best sites.sites . Consequently, thethe lengthlength of the recommended rotation cycle never exceeds 25 years, even in the case of stands with poor rates of growth.

Under average conditions, the final harvest represents areound 70 percent of thethe totaltotal production.production. This final harvest amounts to 200-250200-250 m3/ham3 / ha (mainstem(mainstem volume), withwith aa bolebole volumevolume ofof approximatelyapproximately 170-220170-220 m3/ha.m3 / ha . This correspondscorresponds toto aa cycle-endcycle-end meanmean incrementincrement ofof 8-138 -13 m3/ha/yearm3/ha/year (standing(standing volume of thethe mainmain stem).stem) .

Undergrowth method

To obtain anan exploitable diameterdiameter ofof 4040 cm,cm, itit takestakes betweenbetween 2020 andand 3030 years under conditionsconditions ofof goodgood toto mediummedium fertility.fertility.

The mean timbertimber volumevolume incrementincrement isis thusthus betweenbetween 55 andand 1111 m3/ha/year,m3/ha/year, depending upon densitydensity andand fertilityfertility (class(class 22 toto 3).3)

The maximum productivity recordedrecorded onon aa classclass 11 sitesite withwith aa densitydensity ofof 150 stems/ha and an exploitable diameter of 50 cm is 14.7 m3/ha/year at age 30.

Depending on fertility and plantation density, the following silvicultural recommendationsrecommendations cancan bebe made:made: - 112 --

EXPLOITABLE AGESAGES ANDAND DIAMETERSDIAMETERS FORFOR SAMBASAMBA PLANTATIONPLANTATION SITESITE CLASSES:CLASSES: UNDERBRUSHUNDERBRUSH METHOD

Site Age Density Exploitable Mean volumevolume classes (years) (stems/ha) diam. (e(cm)m) increment (m3/ha/year)(m' f ha/year)

1 30 150 5050.3.3 1414.7.7 27 75 59.8 1111.7.7

2 37 150 44.9 9.4 29 75 50.4 7.77 . 7

3 35 150 35.4 6.0 29 75 40.0 4.7

4 33 100 30.0 3.0

The influenceinfluence ofof densitydensity isis considerable. It must bebe notednoted thatthat plantations ofof thisthis type,type, wherewhere thethe treestrees havehave beenbeen planted forfor apart,apart, areare not thinned atat all.all .

EFFECT OF DENSITY ON DIAMETERDIAMETER INCREMENTINCREMENT SITE CLASS 22

Age (years)(years) 20 23 29 32

Density 75 100100 151500 200 (stems/ha)

Diameter (cm)(em) 3939.7. 7 39.839 . 8 40.740 . 7 40.2

Under good conditions of fertility, the exploitable diameterdiameter ofof 4040 emcm wwillill be reached at an age ranging fromfrom 2020 to 32 years for densities ranging from 7575 toto 200200 stems/ha.stems/ha .

22.4. 4 - Cedrela odorata

The Cedrela odorata is a member ofof thet he MeliaceaeMeliaceae familyfamily nativenative toto tropical America andand foundfound fromfrom Mexico toto Argentina.Argentina . Its naturalnatural range is in moist semi-deciduous and evergreen forest zones with an annual rainfall of 1 200-2 500 mm/year and a drydry seasonseason ofof 22 toto 44 months.months .

It fruits in the drydry season (February-March).(February-March) . There are approximatelyapproximately 50 000 seeds toto thethe kg.kg .

The fragantfragant woodwood isis red,red, softsoft andand light.light. Its traditionaltraditional uses are joinery and cabinet-making. Under plantation conditions,conditions, itsits density rangesranges from 0.350 . 35 to 0.50. The technological characteristicscharacteristics ofof thethe plantation-grown wood are satisfactory.satisfactory. -- 113 --

This species was firstfirst introducedintroduced intointo tropicaltropical Africa earlyearly inin thisthis century (1920 in Ghana,Ghana, 1929 inin Nigeria).Nigeria). In CateCote d'Ivoire,drlvoire, the firstfirst plantations werewere establishedestablished aroundaround 19451945 (Soubré).(Soubre). In 1964-65, plots werewere established atat MopriMopri andand SangouéSangoue forfor behaviourbehaviour trials.trials.

DueDue particularlyparticularly toto thethe extensivenessextensiveness of Cedrela'sCedrela's natural range, a very high degree of genetic variability waswas observed inin the provenanceprovenance trials.

Certain provenances testedtested inin CateCote d'Ivoired'lvoire gavegave veryvery poorpoor resultsresults inin terms of vigour and shape: MissionesMissiones (Argentina).(Argentina). AsAs regardsregards vigour,vigour, thethe bestbest provenances areare ChiquibilChiquibil (Honduras)(Honduras) andand SteSte MarieMarie (Jamaica)(Jamaica) which,which, atat thethe ageage of 88 years,years, hadhad aa meanmean heightheight incrementincrement ofof 2.52.5 m/yearrn/year andand aa meanmean diameterdiameter increment of 33 cm/year.em/year. These two provenances have a good natural pruning aptitude, althoughalthough thethe ChiquibilChiquibil hadhad aa highhigh raterate ofof forkedforked trees.trees .

The best provenances forfor shapeshape areare not the most vigourousvigourous.. With regard to conformation, silviculture and genetic improvement are heavilyheav ily interdependent. VariousVarious introductions confirmconfirm the superiority of specificspecific provenances fromfrom BelizeBelize andand CostaCosta Rica.Rica.

The Ghanaian provenances fromfrom seedseed orchardsorchards dodo notnot fulfilfulfil thethe hopeshopes toto which theythey hadhad givengiven rise.rise . Empirically speaking,speaking, thethe antagonismantagonis~ betweenbetween vigour andand shapeshape -is also toto bebe foundfound inin thethe recommended recommended silviculturalsil vicul tural practices. It will oftenoften bebe necessarynecessary toto givegive preferencepreference toto well-shapedwell-shaped codominant trees by eliminating vigourous dominants lackinglac king commercialcomme rci a l value.v alue.

In its original range,range, a certain number of foliage attacks have been observed asas wellwell asas attacks ofof rootrot,rootrot, although borers (Hypsipyla(Hypsipyla grandella)grandella) are the chief problem.

No borer attacks havehave beenbeen reportedreported inin CateCote d'Ivoire.d! Ivoire. However,However, certain insects (Platipodidae,(Platipodidae, Bostrychidae)Bostrychidae) maymay causecause considerableconsiderable damagedamage toto Cedrela trees. Very localized areasareas ofof rootrotrootrot (Phellinus(Phellinus noxius,noxius, Armillariella spp., Rigidoporus lignosus) have beenbeen observed.observed.

SILVICULTURAL RULES

The results of thethe trialstrials makemake it clear, considering the shapeshape problems encountered, that the highest possiblepossible plantingplanting densities should be adopted: the minimum density envisagedenvisaged isis 11 100100 stems/hastems/ha (MAITRE,(MAITRE, 1979).1979).

For planting purposes, both stumpedstumped plants and baggedbagged plantsplants areare equallyequally suitable.

A yield table isis availableavailable forfor CedrelaCedrela odorataodorata (DUPUY(DUPUY ete t a/.al. 1988), which foresees four different sitesite classes.classes.

The recommended thinningthinning scheduleschedule isis asas follows:follows:

First thinning: This thinning is carried out as soon as the dominant heightheight reaches 9.59.5 m.m. One stemstern out of twotwo isis thinned.thinned.

Second thinning: This thinningthinning takestakes place whenwhen thethe dominantdominant heightheight reachesreaches 1515 m. BeforeBefore thinning, the meanmean diameterdiameter is 19 cm andand thethe basalbasal areaarea isis 19 m2/ha. One sternstem out ofof twotwo isis thinned.thinned. - 114 -

VARIATION IN MEANMEAN GIRTH AS A FUNCTION OF DENSITY AND AGE FOR CEDRELA ODORATA

C80-80-120 120 stems/haS1emstha) C (em)

90 C150-250 S1emstha)sterns/ha

C250-450 stems/haS1emsthaJ 80 -

C500-700 stems/hastemsthaJ 70 1

(800800-1-1 000 stems/hastemsth~

60

40

30

i 2 3 4 5 6 7 8 Age (years) -- 115 --

Third thinning: ThisThis thinningthinning isis carriedcarried outout whenwhen thethe dominantdominant heightheight reaches 2222 m.m. Before thinning,thinning, the mean diameter is 30 emcm andand thethe basalbasal area 19 m2/ha.m2/ha . About 4040 percentpercent ofof thethe standingstanding stemsstems areare thinned.thinned.

Fourth thinning:thinning: ThisThis thinningthinning beginsbegins atat aa basalbasal areaarea ofof 2121 m2/ha.m2/ha. Before thinning,thinning, thethe meanmean diameterdiameter isis approximatelyapproximately 4040 cm.em. One stemstem outout ofof three isis thinned.thinned .

Site classesclasses

1 2 3 44

First thinning Age (years)(years) 3 4 5 7 Density (stems/ha):(stems/ha) : Before thinning 1 100 1 100 J.1 100 1 100 Extracted 550 550 550 550 Volume extractedextracted (m3/ha)(m3/ha) 32 41 40 41

Second thinning Age (years)(years) 5 6 8 12 Density (stems/ha):(stems/ha) : 550 550 550 550 . BefBeforeore thinningthinning 550 550 550 550 275 . Extracted 275 275 275 250250 Volume extractedextracted (m3/ha)(m3/ha) 54 54 53 49 Mean diameter ofof trees extracted (cm)(em) 15 15 14 15

Third thinning Age (years)(years) 8 10 14 21 Density (stems/ha):(stems/ha) : Before thinningthinning 275 275 275 300 Extracted 125 115 100 100 Volume extractedextracted (m3/ha)(m3/ha) 60 54 6 43 Mean diameter of trees extracted (cm)(em) 24 24 23 22

Fourth thinning Age (years)(years) 13 16 22 Density (stems/ha):(stems/ha) :

. Before thinningthinning 150 160 175 Extracted 55 55 50 Volume extractedextracted (m3/ha)(m3/ha) 53 49 40 Mean diameter of trees extracted (cm)(em) 35 33 3311

Final harharvestvest Age (years)(years) 25 28 32 30 Density (stems/ha)(stems/ha) 95 105 125125 200 Volume (m3/ha)(m3/ha) 263 241 217 193 Mean diameter (cm)(em) 61 55 48 36 - 116 -

Spacing trial with 15-year-oldlS-year-old CedrelaCedrela odorata;odorata; Sangou6Sangoue forestforest

Cedrela odorata is a speciesspecies in whichwhich vigourvigour andand shapeshape showshow greatgreat variability. The thinning operations must comply with spacing criteria and at the samesame timetime everyevery carecare mustmust bebe takentaken toto eliminateeliminate poorlypoorly shapedshaped andand impaired trees in thethe dominant storey:storey: the selective aspect of thinnings is fundamentally important. In order to maximize the individual growth increments ofof thethe finalfinal harvestharvest treestrees itit isis necessary toto intervene at an early stage, because inin the juvenile growth phase Cedrela's great thinning response capability allows intensiveintensive butbut fewfew thinnings.thinnings.

The mean incrementincrement inin mainmain stemstem volumevolume rangesranges fromfrom 1111 toto 1919 m3/ha/year, depending uponupon fertility.fertility. AnticipatedAnticipated exploitableexploitable diametersdiameters rangerange fromfrom 4040 toto 60 m.m.

3 - FAST-GROWING SPECIESSPECIES FORFOR TIMBERTIMBER PROMOTIONPROMOTION

3.13 . 1 - - PinesPines

The introductoryintroductory trialstrials withwith CentralCentral AmericanAmerican pinespines resultedresulted inin thethe seselectionl ection ofof twotwo species:species:

- Pinus caribaea var.var. hondurensis

- Pinus oocarpa - 117 -

In its naturalnatural rangerange,t Pinus caribaea varvar.. hondurhondurensisensis is aa speciesspecies tthathat grows inin lowlow landslands andand coastalcoastal valleysvalleys wherewhere standsstands on oneone partpart ofof thet h e wawatershedt ershed are isolatedi solated fromfrom thethe others by different plant formations. BetweenBetween 600 and 800 m high itit isis foundfound mixedmixed withwith PinusPinus oocarpa.oocarpa. The latterl atter speciesspecies generallygener ally grows atat altitudesaltitudes aboveabove 600600 m,mt where itit constitutesconstitutes thethe nextnext vegevegetationt ation level afterafter thethe low-altitudelow-altitude formationsformations wherewhere PinusPinus caribaeacaribaea isis usuallyusually found.found.

PPinusi nus CaribaeaCaribaea var.var. hondurensis, the range of whicwhichh iiss betwebetweene n 12° andand 18°18° North,North, growsgrows fromfrom sea-levelsea-level toto anan altitudealti tude ofof 800800 m.m .

IInn this range, the annual rainfall varies between 1 200 mm/yearmm/year inland to 4 200 mm/year onon thethe AtlanticAtlantic seaboard.seaboard . The dry season ranges from 00 toto 6 months.months.

The differences betweenbetween provenancesprovenances areare considerable.considerable. The selection ccriteriariteria employed areare vigour,vigour, straightness, forking, size and angleangle ofof branches.

The best provenances tested in the moist evergreen forest zone provedproved to be those from (Alamicamba,(Alamicamba, Karawalata, Santa Clara), GuatemalaGuatemal a (Poptun) andand HondurasHonduras (Limones,(Limones, Guanaja). The selection of provenancesprovenances suited to the evergreen forestforest zonezone willwill bebe channelledchannelled towardstowards lowlow altitude areasareas «(< 700700 m)m) wwithi t h anan annual rainfall exceeding 1 800 mm/year (Diabaté(Diabate 1980).1980).

Pinus oocarpa,oocarpa, whose rangerange lieslies betweenbetween 12°12° andand 27°27° North,North, growsgrows atat aaltitudesl titudes ofof 400-1400-1 800800 m.m. This species may also be found locally at altitudes of up to 22 450450 mm (Guatemala)(Guatemala) oror asas lowlow asas 200200 mm (Mexico(Mexico andand Guatemala).Guatemal a) .

In this range, the annual rainfall varies between 700 and 2 500500 mm/yearmm/year and the dry seasonseason rangesranges fromfrom 22 toto 66 months; months; consequently,consequently, therethere isis alsoalso aa high degree ofof interprovenanceinterprovenance variabilityvariability inin thisthis species.species.

In the moistmoist evergreenevergreen forest zone, the bestbest provenancesprovenances are those fromfrom Nicaragua (Yucul,(Yucul, Camelias,Camelias, Rafael)Rafael) andand BelizeBelize (Mt(Mt PinePine Ridge).Ridge) . Selection will be oriented towardstowards provenancesprovenances fromfrom lowlow altitudealtitude areasareas «(< 900900 m)m) in which annual rainfall exceedsexceeds 11 SOO500 mm/year.mm/year.

In lowlandlowland C6teCote d'Ivoire,d'Ivoire, thethe firstfirst fruit-bearingfruit-bearing byby PinusPinus caribaeacaribaea var. hondurensis was observedobserved at thethe ageage ofof 1010 years.years. This species can bebe propagated by graftinggrafting (cleft(cleft andand approachapproach grafts)grafts) andand byby cuttings.cuttings .

The wood isis lightlight (Pinus caribaea: D 1212 == 0.4-0.5)0.4-0 . 5) to semi-heavysemi-heavy (Pinus(Pi nus oocarpa: D 12 = 0.5-0.6), withwi th lowlow to medium shrinkage.shrinkage. Its mechanicalmechanical properties areare mediummedium toto low.low.

SILVICULTURAL RULESRULES

As regards thethe bestbest provenancesprovenances testedtested inin thethe moistmoist evergreenevergreen forestforest zone, at the age ofof 44 yearsyears thethe initialinitial heightheight incrementincrement ofof PinusPinus caribaeacaribaea (1(1.8. 8 to 2.32 . 3 m/year) m/ year) was greater thanthan thatthat ofof PinusPinus oocarpaoocarpa (1(1.2. 2 to 1.51.5 m/year)m/year). .

In thethe lowland moist evergreenevergreen forestforest zone, Pinus caribaeacaribaea var.var. hondurensis has aa medium initialinitial growth rate. The average height is from 0.80 . 8 to 1 m at 1 year, 3-43-4 m atat 22 yearsyears andand 7-97-9 mm atat fourfour years.years. - 118 -

VARIATION ININ GIRTHGIRTH ASAS AA FUNCTIONFUNCTION OFOF DENSITYDENSITY ININ THETHE MOISTMOIST EVERGREENEVERGREEN FOREST ZONE FOR PINUS CARIBAEA

C (em)

100 .. e400 s1ems/ha J ","

50

O ~---'---'----.---.---.----r---r---.---.---'r---.---.---.---~ o 5 1010 Age (years) - 119 --

22-year-old pines;pines; Yapo forest

The recommended plantingplanting densitydensity isis 11 100-1100-1 500500 stems/ha.stems/ha .

In the moist evergreen forestforest zone,zone, thethe proposed provisional thinningthinning schedules is asas follows:follows:

- When thethe meanmean heightheight isis 77 toto 99 m m andand thethe meanmean diameterdiameter 1010 toto 121 2 cm,em, the plants should be thinned outout toto bringbring thethe densitydensity downdown to 800-900800-900 stems/ha.stems/ha . The age of thethe standstand isis thenthen 3-43 - 4 years.years .

- When the meanmean heightheight isis 1414 toto 1616 mm andand thethe mean diameter 1818 to 2020 ern,cm, the firstfirst proper thinningthinning reducesreduces density to 500-600 stems/ha.stems/ha . The age of the standstand isis thenthen 77 toto 99 years.years .

- When the meanmean height height isis 1717 toto 1919 mm andand thethe meanmean diameterdiameter 2323 toto 25 cm,em, a second thinning reduces density toto 350-400350-400 stems/ha.stems/ha . The age ofof thethe standstand isis thenthen 1010 toto 1212 years.years .

- At thethe ageage ofof aboutabout 1515 years,years, thethe thirdthird thinningthinning bringsbrings thethe stand's densitydensity downdown toto aboutabout 200200 stems/ha.stems/ha. TheThe particularsparticul ars ofof any furtherfurther thinningsthinnings stillstill remainremain toto bebe specified.specified . - 120 --

At thethe ageage ofof 8-108-10 years,years, withwith aa densitydensity ofof 600600 stems/ha,stems/ha, thethe meanmean standing mainmain stemstem volumevolume incrementincrement isis aroundaround 2525 m3/ha/year.m3/ha/year.

For an exploitable diameter of 60 emcm the rotation cycle is approximatelyapproximately 3030 years.years.

In thethe pre-forestpre-forest zone,zone, preference will be givengiven toto low-altitudelow-altitude provenances ofof PinusPinus oocarpa.oocarpa.

At age 10, with a density of 645 stems/ha,stems/hal the meanmean diameterdiameter is 18 emcm and thethe meanmean totaltotal heightheight 1717 m.m.

At age 15,15, with a density of 420 stems/ha, the mean diameterdiameter is 23 emcm and the meanmean totaltotal heightheight isis 2222 m.m. The mean main stem volume increment isis 1111 m3/ha/year (Outtara(Outtara 1982).1982) .

3.2 - Gmelina arborea

Gemelina arborea arborea isis a membermember of the verbenaceaeverbenaceae family. ItIt is a species of Asian originorigin whosewhose naturalnatural rangerange isis inin IndiaIndia ((latitude 28° North to 5°5° South, longitude 70°70° toto 95°95° East).East). It ranges from PakistanPakistan toto Bangladesh,Bangladesh, Burma, Sri Lanka,Lanka, Thailand, Laos, Kampuchea, Viet Nam andand thethe southernsouthern provinces ofof China.China. It is also foundfound inin MalaysiaMalaysia andand inin thethe Philippines,Philippines, where itit appears toto bebe sub-spontaneous.sub-spontaneous. It hashas alsoalso beenbeen introducedintroduced into manymany countries inin thethe moist tropicaltropical zonezone ofof Africa,Africa, wherewhere itit hashas been growing forfor several decades.decades.

In its original arealarea, it is found fromfrom sea-level up to an altitude ofof 1 500500 m.m. The annual rainfall varies fromfrom 700700 mm/year (dry(dry deciduousdeciduous forest)forest) to 4 500500 mm/yearmm/year (moist(moist deciduousdeciduous forest).forest) . The minimum temperatures range from -1°C-1°C toto 16°C16°C andand maximamaxima fromfrom 38°C38°C toto 48°C.48°C.

Such an extensiveextensive range implies differentiation intointo numerous ecotypes. Two varietiesvarieties havehave beenbeen identifiedidentified inin India:India: var. glaucescens and var.var. canescens.

In its natural state, the Gmelina is a notnot veryvery gregariousgregarious speciesspecies extending fromfrom moistmoist evergreenevergreen forestforest areasareas toto drydry forestforest areas.areas. In thethe latter, itit oftenoften growsgrows inin shrub-likeshrub-like form.form. It cannot tolerate hydromorphic soils or soils thatthat areare floodedflooded forfor longlong periods.periods.

This deciduous speciesspecies isis leaflessleafless inin thethe drydry season.season. In its natural range, it flowersflowers atat thethe endend ofof thethe drydry seasonseason andand bearsbears fruitfruit approximatelyapproximately two monthsmonths later.later. There areare inin factfact considerableconsiderable inter-inter- andand eveneven intra-intra­ individual differencesdifferences inin floweringflowering andand fructificationfructification periods.periods.

In CateCote d'Ivoire, fructificationfructification extends fromfrom December toto June.June. TheThe fruit is aa fleshyfleshy drupedrupe whosewhose kernelkernel containscontains fromfrom oneone toto fivefive seeds,seeds, mostmost frequently two. There are approximatelyapproximately 800800 fruitsfruits perper kilo.kilo.

On plantations, thethe treestrees beginbegin toto bearbear fruitfruit atat thethe ageage ofof 3-43-4 years.years. Each treetree produces aboutabout 5-65-6 kgkg ofof fruit,fruit, equivalentequivalent toto approximatelyapproximately 0.50.5 kgkg of depulped fruitfruit perper tree.tree.

In cultivated stands,stands, thethe mean lifespan of the trees ranges from about ten years on thethe poorestpoorest sitessites toto aroundaround fiftyfifty onon thethe bestbest sites.sites. Gmelinas have very goodgood stumpstump sproutingsprouting abilityability andand cancan easilyeasily bebe growngrown fromfrom cuttingscuttings (u(unlignifiednlignified shoots).shoots) . - 121 --

The seedsseeds germinategerminate fromfrom oneone toto twotwo weeksweeks afterafter sowing,sowing, with no preliminary treatment required.required . However, soaking the seeds for twenty-four

hours regularizesregularizes sproutingsprouting times.times. For planting-out,planting-out I both baggedbagged and/orand/or stumped plants cancan bebe usedused withwith equallyequally goodgood results.results.

The bestbest provenancesprovenances are selectedselected on thethe basisbasis ofof the followingfollowing criteria: cylindrical, straightboles,straightboles, qualityquality andand heightheight ofof naturalnatural pruning,pruning, forking height, multiplemUltiple stems.stems.

In the moist evergreen forestforest zone,zone, thethe bestbest testedtested provenancesprovenances are:are:

- Tamilnadu (India),(India), whichwhich provedproved veryvery vigorousvigorous butbut branchy;branchy;

- Bamoro (C6te(Cote d'Ivoire) andand KundrukutuKundrukutu (India),(India), which did well in termsterms of straightand, cylindricacylindricalcolel cole and vigour,vigour, with average self-pruningself-pruning qualities.qualities.

In the moist semi-deciduous forest zone,zone, the best tested provenances are: Baramura (India),(India) , Shikaribari (India)(India) and BamoraBamoro (C8te(Cote d'lvoire),d'Ivoire), which combine good vigour withwith goodgood toto averageaverage shapeshape characteristics.characteristics.

withWith regard to shape problems, the first observations from provenanceprovenance trials conducted inin . C8teCote d'Ivoired'Ivoire showshow that:that:

- the multiplemultiple stemstem traittrait frequently presentpresent in GmelinaGmelina is independent ofof provenance andand seems instead to be linkedlinked toto site (type(type ofof plantation,plantation, soil,soil, ...);. .. ) ;

- defective pruning (presence(presence of stubs) is worseworse whenwhen branchinessbranchiness is also present;present;

- cylindrical treestrees areare straight,straight, verticalvertical andand well-pruned;well-pruned;

- a straightbole, the presencepresence of stubs and knotknot sizesize are site-independent traits.traits.

SILVICULTURAL RULESRULES

The Gmelina, which isis very frequently introduced inin experimental short-short­ rotation reforestation programmes,programmes, isis aa fast-growingfast-growing species.species.

In the moist forest zones,zones, thethe meanmean manman totaltotal height isis 1.5 mmat at 1 yearyear and (2.5 mm at 2 years. Introduced in the pre-forest zone,zone, thethe GmelinaGmelina hashas proved toto bebe aa promisingpromising reforestationreforestation species.species . With a densitydensity ofof 250-350250-350 stems/ha, at the age of 11 years the following mean increments are obtained:

Geographical Mean incrementincrement in:in:

area height (m/year) diameter (cm/year) volumevolume ((m3/ha/year)m3/ha/year)

EvergreenEve rgreen 2.5/32.513 Semi-deciduous 2.212.72.2/2.7 2.5/32.513 2012520/25 Pre-forest 1.1.5/2512 1.5/21.512 1512015/20 - 122 --

In thethe moistmoist evergreenevergreen forestforest zone,zone, with 11 100 stems/ha and notnot thinned, Gmelina hashas aa mean diameterdiameter of 20 cmem (DHP)(DHP) at the age ofof 8-10 yearsyears with a mean strong wood incrementincrement ofof 30-4030-40 m3/ha/year onon experimentalexperimental plots.plots.

At this density, competitioncompetition appearsappears veryvery earlyearly on.on. By the age ofof 3-43-4 years, with timbertimber production as the goal, thinning to bringbring thethe densitydensity downdown to 600-700 stemsstems isis necessary.necessary. At 5 years, the meanmean diameter is around 13-15 em.cm.

Frequent problems with natural shape (straightbole,(straightbole, forking,forking, multiplemultiple stems) and pruning lead us to recommendrecommend plantingplanting densitiesdensities ofof thethe order of 1 100100 stems/hastems/ha whichwhich ensuresensures aa quicklyquickly closedclosed covercover favourablefavourable to natural pruning andand aa sufficientlysufficiently largelarge stockstock forfor aa goodgood selectionselection ofof treestrees atat thethe time of thinningthinning (CABARET,(CABARET, 1988).1988).

Silvicultural studiesstudies indicateindicate thethe following silvicultural imperatives:

a high planting density (1(1 100100 stems/ha);stems/ha); a schedule of heavy and earlyearly thinnings;thinningsi an expexploitableloitable age and diameter that vary in relation to fertility.

The thinningthinning scheduleschedule dependsdepends onon sitesite fertility.fertility. The exploitableexploitable diameter increasesincreases withwith fertility.fertility.

The proposed silviculturalsilvicultural rulesrules are:are:

'a thinning scheduleschedule ofof 33 thinnings;thinnings; an inte*rvalinte'rval ofof 33 toto 1212 yearsyears betweenbetween thinningsthinnings,, dependingdepending upon site fertility andand standstand age;age; an exploitable diameter ranging from 35 to 6060 cm,cm, dependingdepending uponupon site fertility;fertility; an exploitable age of 23 to 55 years,years, dependingdepending uponupon sitesite fertilityfertility and exploitableexploitable diameter.diameter.

Fertility levellevel Thinning operation 1 2 3 4 5

NaveN ave (stems/ha)(stems/ha) 1 111 1 111 1 111111 1 111 1 111 1 Age (years) 3 4 5 6 10 Ho over 9 metres

NaveN ave (stems/ha)(stems/ha) 400 400 400 400 500 2 Age (years) 6 7 9 13 17 Dg. (cm)(em) 2323.8. 8 23.5 22.8 22.2 18.8

NNave ave (stems/ha)(stems/ha) 200 200 200 200 250 3 Age (years) 9 11 15 24 35 Dg. (cm)(em) 34.3 3333.9. 9 32.9 32.2 26.9

Final harvest N (stems/ha) 115 115 115 115 150 Age (yea(years)rs) 23 27 30 40 55 Dg.Dg . (em)(cm) 6060.2. 2 57.2 50.1 45.0 35.3

N aveave : Mean densitydenslty beforebefore thinningthlnnlng

Dg : Mean diameter - 123 -

VARIATION IN GIRTH AS A FUNCTION OF AGE AND DENSITY FOR GMELINA ARBOREA

C (em)

150

100

1100 stems/ha

50

01------,------,------,-----~~ 0o 10 2020 30 Age (years)(years) - 124 --

The productivity of the plantations depends primarily on the fertility of thethe trialtrial sites.sites.

Five site classesclasses havehave beenbeen identified.identified.

Site Harvestability Mean incrementincrement classes (m3/ha/yr)

Age Dg V Final Total (years) (em)(cm) (m3/ha) harvest harvest

1 23 60.2 350 15.2 20.3

2 27 57.2 314 11.11.6 6 1616.2. 2

3 30 50.1 236 7.8 11.11.8 8

4 40 45.0 187 44.7. 7 7.7

5 55 35.2 144 2.6 4.3

The productivity of GmelinaGmelina arboreaarborea plantations ranges from 44 toto 2020 m3/ha/year (main(main stemstem volume).volume) .

The pn~duetivitypräductivity gradient, expressed by fertility,fertility, isis closelyclosely dependentdependent on thethe rainf-'illrain~~il regime.

The best productivity datadata isis recorded in moist forest areas where the rainfall isis highesthighest andand mostmost evenlyevenly distributed.distributed.

Forest zone Moist Pre-forest Guinean forest area savannah

Exploitable diameter (cm)(em) 45 to 6060 30 to 3535 25 to 35 Exploitable age (years)(years) 15 to 25 25 to 4545 30 to 5555

Mean increment (m3/ha/year) 11 to 20 5 to 1313 4 to 99

In closed forest areas thethe mean volume incrementincrement rangesranges fromfrom 11 to 2020 m3/ha/yearm3/ha / year andand thethe exploitableexploitable diameterdiameter fromfrom 4545 toto 6060 cm.em.

In the pre-forest zone the mean volume increment ranges from S5 to 1313 m3/ha/year andand thethe exploitableexploitable diameterdiameter rangesranges fromfrom 3030 toto 4545 cm.em .

In savannahsavannah areasareas thethe meanmean volumevolume increment rangesranges from 4 to 9 m3/ha/year. The exploitable diameterdiameter rangesranges fromfrom 2525 toto 3535 cm.cm.

The final harvest constitutesconstitutes 6060 toto 7575 percentpercent ofof thethe totaltotal harvest.harvest. - 125 --

Young Gmelina plantation

In the lightlight ofof thethe availableavailable data,data, thethe followingfollowing silviculturesilviculture rulesrules can be recommended forfor thethe closedclosed forestforest zone:zone:

- At thethe ageage ofof aboutabout 3-43 - 4 years,years, the firstfirst thinningthinning reducesreduces density toto 400400 stems/ha.stems/ha. Before thinning, the treestrees inin thethe stand have a mean diameter ofof 1010 cm,em, aa mean height of 1010 m and basal area ofof 99 m2/ha.m2/ha .

- At thethe ageage ofof aboutabout 5-75 -7 years,years, the second thinningthinning reducesreduces density toto 200 stems/ha. Before thinning, thethe mean diameter isis 20 cm,em, thethe mean height 1515 m andand thethe basalbasal areaarea 1313 m2/ha.m2/ha.

- At about 8-108- 1 0 years, thethe thirdthird thinningthinning reducesreduces densitydensity toto 125125 stems/ha. The mean diameter is 30 em,cm, thethe meanmean heightheight 20m20m andand the basal areaarea 1515 m2/ha.m2/ha.

For an exploitableexploitable diameterdiameter ofof 4545 cm,em, the rotation cycle isis 15-2015-20 years. The mean volumevol ume incrementincrement isis fromfrom 1010 toto 1515 m3/ha/year.m3/ha/year.

In the pre-forest zone,zone, thethe growthgrowth raterate ofof GmelinaGmelina arborea is stillstil l attractively high. ForFor maturemature standsstands onon fertilefertile sitessites thethe followingfollowing figuresfigures are obtained:

Age Density Girth at 1.l. 30 m g (years) (stems/ha) (cm)(em) (m2/ha)

16 296 98.4 23.4

16 520 7979.5. 5 26.6

26 292 110110.0. 0 28.9

26 516 84.4 29.7 - 126126 --

4 - - SPECIES TOTO BEBE CONFIRMEDCONFIRMED

4.1 -- Padouk (Peterocarpus(PeterOCarpU5 soyauxi)soyauxi)

The Padouk, which belongs to the Papilonaceae family, is a native of Equatorial Africa,Africa, wherewhere itit isis foundfound fromfrom NigeriaNigeria toto Zaire.Zaire. It isis aa moistmoist evergreen forestforest speciesspecies thatthat seldomseldom exceedsexceeds aa diameterdiameter ofof 11 m.m.

Its woodwood is brightbright red inin colourcolour and is semi-heavy (D(D 121 2 == 0.650.65 -- 0.85)0.85) and hard.hard. It darkens whenwhen exposedexposed toto light.light. It is used forfor indoorindoor andand outdoor woodwork, cabinet-makingcabinet-making andand veneering.veneering.

The Padouk was successfullysuccessfully introducedintroduced in the moist evergreen forest zone ofof CeyteCote d'Ivoired'Ivoire inin 1960.1960.

The Padouk isis susceptiblesusceptible toto "platypes""platypes" attacksattacks onon thethe bole.bole.

\ SILVICULTURAL RULESRULES

This isis a fast-growing species:species: atat 11 yearyear thethe meanmean heightheight isis 1.51.5 toto 22 m, at 2 years it isis 4 toto 5 m and at 6 years it reaches 1515 to 18 rnm (ADOU(ADOU KOUABLAN 1981).1981) .

At thethe age of 6 years, thethe meanmean height incrementincrement isis aroundaround 2.22.2 m/yearm/year with aa meanmean diameterdiameter incrementincrement ofof 2.52.5 cm/year.cm/year.

When planted atat aa densitydensity ofof 625625 stems/hastems/ ha withwith nono thinningsthinnings (fuelwood,(fuelwood, energy-oriented plantation),plantation), thethe meanmean increment in main stemstern volumevolume isis 3030 m3/ha/year atat ageage 1515 withwith aa meanmean diameterdiameter ofof 2525 toto 3030 cm.cm .

At: age 17, inin thethe casecase ofof aa plantationplantation thinnedthinned downdown toto 400400 stems/ha,stems/ha, the mean increment inin thethe diameterdiameter ofof thethe 150150 largestlargest treestrees isis 2.52. 5 cm/year.cm/year .

However, inin 15-year-old treestrees withwith aa diameterdiameter ofof 3535 cmern thethe percentage of sapwood isis 6060 percent.

The first provisional silviculturalsilvicultural recommendationsrecommendations areare asas follows:follows:

the planting density isis 700700 stems/ha.stems/ha.

when the mean height isis 99 toto 11 m, the mean diameter isis 1010 toto 1212 cmcm and the basal area 6 to 8 m2m2/ha,/ ha, the first thinning is carried out to reduce density to 300-350 stems/ha. TheThe standstand's' s ageage is 4 to 5 years.

when the mean height isis 1313 toto 1515 m, thethe mean diameterdiameter isis 1515 toto 1717 cm andand thethe basalbasal areaarea 6 to 8 m2/ha,m2 /ha , a secondsecond thinningthinning reducesreduces density to 125-150 stems/ha.stems/ ha. The stand'sstand's ageage isis 66 toto 88 years.years.

With an exploitable diameterdiameter ofof 5050 to 60 cm, thethe rotationrotation cycle is fromfrom 30 tot o 40 years. The mean increment inin main stemstern volume isis of thethe order ofof 1515 m3/ha/year atat ageage 15.15. - 127] 2 7 -

VARIATION IN GIRTH ASAS AA FUNCTIONFUNCTION OFOF AGEAGE ANDAND DENSITYDENSITY ININ PADOUKPADOUK IN THE MOIST EVERGREEN FOREST ZONE

c (em)(cm) 200 stemsiha J 110 e

100

90

80

70

60

50

40

30

20

10

22 3 4 5 66 7 8 9 10 11 12 13 14 15 16 17 . AgeAge(years) (years) - 128 -

4.2 Cordia alliodoraalliodora

This deciduous sun-lovingsun-loving species native to Latin America belongs to the Borraginaceae family.family_ It is a medium-sized, buttressed tree that can reach a diameter ofof 11 m m andand aa heightheight ofof 3030 m.m.

Cordia alliodora has a very extensive range from latitudes 25° North (Southern Mexico) toto 25°25° SouthSouth (Northern(Northern Argentina).Argentina) .

In this area,area, thethe annualannual rainfallrainfall rangesranges fromfrom 11 000000 toto 55 000000 mmmm perper yearyear.. Cordia isis a low-altitude species (<« 500 m) which can locally reach anan altitude ofof 22 000000 mm (Columbia)(Columbia) The duration of the rainy seasonseason ranges from o0 to 55 months.months.

The extensextensivenessi veness of its natural range (which is, moreover, discontinuous) gives riserise toto aa highhigh degreedegree ofof geneticgenetic variability.variability. The provenance trials conducted in CoteCotê dd'Ivoire I Ivoire revealed very high interprovenance variability: at the age of 4-54-5 yearsyears thethe mean totaltotal heightheight ranged fromfrom 7 to 1717m m accordingaccording toto provenanceprovenance amongstamongst those testedtested at Sangoue.Sangou6.

The best introducedintroduc ed provenanceprovenance isis "FincaIIFinca lala Fortuna"Fortuna ll (Honduras).(Honduras) . At age 4-5 years, itsits meanmean dendometricaldendometric al characteristicscharacteristics are:are:

Density Total Girth atat Pruned Fork Basal height 1.30 m height height area

711 stems/hastems/ ha 17 m 56 cm 11 m 11 m 18 m2m2/ha/ ha

The bent stem characteristic reportedreported inin certaincertain standsstands appearsappears toto bebe provenance-linked.

In reforestation,reforestation, the best resuresultslts have been reported in thethe evergreenevergreen zone with annualannual rainfallrainfall exceedingexceeding 11 600600 mm/year.mm/year.

In CoteCate d'Ivoire flowering begins at 4-54 -5 years, in December-February; the tree fruitsfruits atat thethe beginningbeginning ofof thethe rainyrainy seasonseason (June(June toto August).August) .

The wood isis lightlight toto veryvery lightlight (D 12 = 0.40.4 - 0.5), soft, of lowlow nervosity with lowlow toto mediummedium mechanicalmechanical properties.properties. Its durability andand impregnability areare medium.medium . The wood sometimes fluffsfluffs whenwhen sawn.sawn. It is easy tot o season and machinemachine.. Its principalprincipal usesuses areare indoorindoor woodwork,woodwork, cabinet-makingcabinet-making and veneer-peeling.veneer-peeling. - 129 -

VARIATION ININ MEAN GIRTHGIRTH ASAS AA FUNCTIONFUNCTION OFOF AGEAGE ANDAND DENSITYDENSITY FORFOR CORDIACORDIA

C (em)

100

90

80

250 stems/ha 70

60

5050

40

( 1 000 stemslha ) 30

20

10

2 3 4 5 66 7 8 99 10 11 12 Age (years) - 130l30 --

15-year-old plantation ofof CordiaCordia alliodoraalliodora SangouéSangoue forestforest

SILVICULTURAL RULESRULES

The effecteffect of sitesite conditionsconditions on thethe successsuccess or failurefailure of CordiaCordia alliodora introductionsintroductions isis considerable.considerable.

Cordia is sensisensitive ti ve toto water supply imbalances of climatic, topographic and/or edaphicedaphic origin.origin. In particular,particular, its introduction shouldshould not bebe attempted on thethe followingfollowing typestypes ofof SiteS:sites:

Lowland oror upslopeupslope areasareas withwith highlyhighly porousporous soilssoils (sandy(sandy texture),texture) , where periodic rainfallrainfall deficitsdeficits areare amplifiedamplified byby thethe topographictopographic and edaphic conditions;conditions;

Down slopes lope areas on compact, imporous soils (clayey(clayey texture) thatare likely to bebe waterloggedwaterlogged forfor lengthylengthy periods,periods, especiallyespecially inin moistmoist evergreen forest.forest.

The best growth isis observed on soils of balanced texture, of colluvial origin, that have a regularregular waterwater supplysupply withoutwithout anyany markedmarked temporarytemporary deficitsdeficits or excesses. These sitessites areare oftenoften locatedlocated onon thethe lowerlower slopes.slopes. - 131 -

Cordia hashas aa highhigh raterate ofof initialinitial growth:growth: atat thethe ageage ofof 55 yearsyears itsits mean totaltotal heightheight isis fromfrom 1212 toto 1515 m,mt andand atat 1010 years itit reaches 2525 m (MAITRE,(MAITRE, 1979)1979). .

TheThe provisionalprovisional silviculturalsilvicultural rulesrules proposedproposed forfor thisthis speciesspecies are:are:

planting density:density: 700700 stems/ha.stems/ha.

at thethe ageage ofof 44 years,years, thethe firstfirst thinningthinning reducesreduces densitydensity toto 500500 stems/ha. Before thinning,thinningl thethe meanmean girthgirth isis aroundaround 4040 cm.ern.

at thethe ageage ofof 88 years,years, aa secondsecond thinning reduces density toto 250250 stems/ha.stems/ha . Before thinning,thinning, thethe meanmean girthgirth isis aroundaround 5555 cm.em.

one or twotwo supplementarysupplementary thinnings are to be established to bring the standstand toto itsits finalfinal density.density.

TheThe rotationrotation cyclecycl e isis aroundaround 30 years toto provideprovide anan exploitableexploitable diameter of 5050 cm.em.

4.3 - Cleistopholis glaucaglauca

Cleistopholis glaucaglauca (Sobu)(Sobu) is aa membermember of the AnnonaceaeAnnonaceae family.family. It is a moist secondarysecondary forestforest speciesspecies foundfound fromfrom CameroonCameroon toto .Angola.

In natural forestforest itit reachesreaches aa totaltotal heightheight ofo f 35-4035-40 m with a diameter of 80-10080-100 cm.em.

The white-colouredwhite-coloured wood is lightlight andand veryvery soft,soft, withwith considerableconsiderable shrinkage duringduring seasoning.seasoning. The suitabilitysuitability of thisthis speciesspecies forfor timbertimber remains toto bebe confirmed.confirmed.

The first plantations established inin ZaireZaire showed fastfast initial growth. At the age of 17 years, with a density of 800 stems/ha,stems/ha, the meanmean incrementincrement inin main stem volume isis aroundaround 3535 m3/ha/year.m3/ha/year.

This species was first successfully introducedintroduced inin CateCote dd'Ivoire t Ivoire in 1966 in the evergreen forestforest zone,zone, usingusing seedsseeds fromfrom Gabon.Gabon.

SILVICULTURAL RULESRULES

CleistopholisCleistopholis glaucaglauca isis aa sunloving, fast-growing species.species. However, unlike many experimentally cultivatedcultivated species,species, itsits meanmean heightheight incrementincrement doesdoes not reach itsits maximum levellevel untiluntil thethe ageage ofof 10-1210-12 years.years.

at 2 years the mean height incrementincrement isis 1.51.5 m/year,m/year,

at 4 years it is between 22 and 2.52.5 m/year,

at 8 years it is betweenbetween 2.52.5 andand 33 m/year,

at 12 years it reaches 3.23.2 m/year. - 132 -

18-year-old CleistopholisCleistopholis glauca;glauca; YapoYapo forestforest

At the age of 22 yearsyears thethe meanmean heightheight isis 2.5-32.5-3 m;mi at 4 years itit isis 8-10 m and at 6 years itit isis 16-1816-18 mm (PESME(PESME 1982).1982) .

The provisional silviculturalsilvicultural rulesrules areare asas follows:follows:

The recommended planting densitydensity isis 400-500400-500 stems/ha.stems/ha.

When the mean heightheight isis aboutabout 33 m,m, atat thethe ageage ofof aroundaround 2-32-3 years,yearR, the trees shouldshould bebe thinnedthinned outout toto 200200 stems/ha.stems/ha.

Around the age ofof 5-65-6 years,years, whenwhen thethe meanmean heightheight isis 15-17m,15-17m, thethe mean diameterdiameter aboutabout 20 cmem andand thethe basalbasal area is 8-10 m2/ha,m2/ha, thinning reducesreduces thethe densitydensity toto 8080 stems/year.sterns/year .

At ageage 13,13, with aa densitydensity ofof 6060 stems/ha,stems/ha, the meanmean incrementincrement inin mainsteim volumevolume isis 1414 m3/ha/year.m3/ha/year. For an exploitable diameter ofof 6060 cmern the rotation cyclecycle isis 15-2015-20 years.years.

Planted out with a density of 700 stems/ha with no thinnings, the mean increment in mainmain stem volumevolume is 40-45 m3/ha/year at 10-12 years on experimental plantations.plantations . The mean diameter isis aroundaround 3030 cm.cm.

4.4 - Maesopsis eminiieminii

The Maesopsis belongsbelongs toto thethe RhamnaceaeRhamnaceae family.family. This closedclosed forestforest species appears toto have twotwo ecotypesecotypes withwith differentdifferent growthgrowth patterns:patterns:

The first, described byby Aubréville,Aubreville, isis nativenative toto WestWest AfricaAfrica (it(it isis found from Liberia toto Cameroon).Cameroon). It is a tree of second-rank sizesize that reaches a maximum height of 15-20 meters and a maximummaximum diameterdiameter of 25-30 em,cm, and is of no interest from the reforestation standpoint. - 133 --

The secondsecond isis nativenative toto EquatorialEquatorial Africa (where(where itsits rangerange extendsextends from Gabon toto Angola, Kenya,Kenya, TanzaniaTanzania ...... ). It is a medium-sizedmedium-sized tree that reaches aa heightheight ofof 30-3530-35 m and a diameter ofof 100-120100-120 cm.cm.

This equatorialequatorial speciesspecies rangesranges fromfrom latitudeslatitudes 8°8° NorthNorth toto 2°2° South,South, with annual rainfallrainfall fromfrom 11 500500 toto 33 000000 mm/year and a dry season lasting less than 44 months.months . It growsgrows at altitudes below 700700 m.m.

TheThe wood isis lightlight (D(D 1212 == 0.4),0.4), ofof aa coppery-browncoppery-brown colour,colour, soft,soft, notnot very durable butbut easilyeasily impregnated.impregnated. It can be used forfor indoorindoor carpentery,carpentery, boxes, and possibly alsoalso forfor veneer-peeling.veneer-peeling .

This species, which hashas beenbeen successfullysuccessfully plantedplanted inin lowerlower CeyteCote dd'Ivoire' Ivoire since 19661966 usingusing seedsseeds fromfrom Uganda,Uganda I is usedused forfor reforestationreforestation purposes, particularly inin Zaire.Zaire. There are about 750 seedsseeds toto thethe kilogram.kilogram.

Infestations ofof trunktrunk borers,borers, aboveabove allall atat thethe levellevel ofof pruningpruning scars,scars, have been observed.observed.

19-year-old Maesopsis eminii; Anguededou forestforest - 134 -

SILVICULTURAL RULESRULES

This isis a fast-growingfast-growing no-cover species;species; inin Zaire the mean heighthei ght at the age of 55 years isis 1717 mm withwith aa meanmean diameterdiameter ofof 1414 cm.ern.

In CateCote d'Ivoired'lvoire the initialinitial growth is fast;fast; the mean incrementincrement in total height isis 2.5-32 . 5-3 m/year.m/year. At 1 year thethe mean totaltotal heightheight isis 22 m;m; atat 22 years itit isis 44 m;mj at 33 yearsyears itit rangesranges fromfrom 77 toto 88 m;rn j and at 55 yearsyears itit is 11-13 m (PESME,(PESME, 1982).1982).

The firstfirst provisionalprovisional silviculturalsil vicultural rulesrules areare asas follows:follows:

the planting densitydensity shouldshould bebe aroundaround 500500 stems/ha;stems/ha;

at about the age of 3 years, when the mean height reaches 7-87 -8 m,ffi, the mean girth isis 25-3025-30 cmcm andand thethe basalbasal areaarea 3-43-4 m2/ha,m2/ha, the firstfirst thinning reducesreduces thethe densitydensity toto 250-300250-300 stems/ha;stems/ha;

at around 66 years, when thethe mean height isis 11-13 m,rn , thethe mean girth 65-75 cm and the basalbasal areaarea 10-1210-12 m2/ha,m2/ha, thethe secondsecond thinningthinning reducesreduces the density toto 100-125 stems/ha.stems/ha.

At the a$eage of 13 years,years, thethe meanmean diameterdiameter incrementincrement is 2.32.3 em/yearcm/year withwith a density ofof 130130 stems/ha.stems/ha.

For an exploitable diameter of 5050 cm,em, the rotation cycle is about 25 years.

4.5 - Funtumia elasticaelastica

The Funtumias (Apocynaceae(Apocynaceae family)family) are smallsmall toto medium-sizedmedium-sized trees.trees. They are divided into two species: F. africana and FF.. elasticaelastica (Pouo), whichwhich do not differ greatlygreatly fromfrom thethe morphologicalmorphological standpoint.standpoint. TheThesese are species native to the evergreen forestforest andand transitionaltransitional semi-deciduoussemi-deciduous forest.forest. They areare sun-lovers thatthat colonizecolonize clearingsclearings andand gaps.gaps . They can also grow with a certain amount of cover above them.them. The PouotsPouo's range is very extensive. They a~eare found from West Africa toto CentralCentral Africa.Africa.

The economeconomici c importanceimportance of the Pouo (Funtunia(Funtunia elastica), which used to be tappedtapped forfor rubber,rubber, was abruptly reduced to thethe secondsecond rankrank withwith thethe development ofof HeveaHevea plantations.plantations . However, for the last twotwo decadesdecades thisthis species has been used on a massive scalescale forfor matchwood.

The wood is light (D(D 1212 == 0.5),0 .5), very soft,soft, ofof lowlow toto medium nervosity.nervosity. Natural seasoning isis easyeasy toto effect,effect, withwith lowlow toto medium shrinkage. This wood is easy to saw,saw, toto peelpeel forfor veneerveneer andand toto plane,plane, andand holdsholds veryvery wellwell whenwhen gluedglued or nailed. However, itsi ts natural durabilitydurability isis low.low.

It bearsbears fruitfruit veryvery early.early. Fruit-setting isis at its maximummaximum inin DecemberDecember-January.- January . The fruits are elongated podspods groupedgrouped inin pairs.pairs. The seeds are small and very numerous.numerous . They are dark-brown, elongatedelongated inin shape,shape, withwith a crest of long silky hairs atat thethe top.top . -- 135 --

9-year-old Pouo;POllOi YapoYapo forestforest

The POllOPouo is susceptiblesusceptible to attacksattacks byby leaf-eatingleaf-eating caterpicaterpillarsllars that cancan be controlled byby applicationsappl ications ofof "Decis".5IIDecis II. S

SILVICULTURAL RULES

The recommendedrecommended plantingplanting densitydensity isis 1 100 stems/ha.stems/ha. The PouoPOllO isis aa species withwith aa mediummedium raterate ofof growth.growth. At oonene year, the mean height isis fromfrom 0.5 to 0.80.8 m.m. The young trees' shape is oftenoften defectivedefective andand requiresrequires pruningpruning to shapeshape thethe buttwood.buttwood . At thethe ageage ofof 66 years,years, thethe meanmean heightheight isis aboutabout 8 metres.

Without thinning,thinning, thethe PouoPOllO attainsattains aa mean diameterdiamet er of 10 emcm towards the age of 6-106 - 10 years.yea rs. At densities ofof 300300 stems/ha,stems/ha, thethe meanmean diameterdiameter atat ageage 2525 is 20 em.cm. The hundred largestlargest stemsstems perper hectarehectare havehave aa meanmean diameterdiameter of of 2727 cm,em, with a mean incrementincrement ofof aboutabout 11 cm/yearem/ year (K.(K. KOFFI 1989).1989) .

At this age, the mean volume increment isis 6 m3m3/ha/year./ ha/ year. UnderUnder averageaverage conditions, one may reasonablyreasonably count on aa meanmean diameterdiameter incrementincrement ofof 1.51.5 em/yearcm/year upup to thethe ageage ofof 15 years, and ofo f 1 cm/yearem/ year afterafter that.that. TheThe exploitable diameterdiameter ofof 4545 cmcm shouldshould bebe reachedreached byby thethe ageage ofof 35-4035-4 0 years.years.

5 Registered trademark.trademark. - 136 --

44.6 . 6 - Araucarias

In the tropics, twotwo species of the genus Araucaria are of interest for timberwood production inin thethe moistmoist savannahsavannah zone.zone.

These are:are:

Araucaria cunninghamii (Hoop ),Pine) I a treetree nativenative toto QueenslandQueensl and (Australia) andand PapuaPapua NewNew Guinea, at latitudeslatitudes between 88 andand 30°30° South. It grows fromfrom sea-levelsea- level to an altitude of 22 400400 m,m, withwith annual rainfallrainfall ofof 11 000000 to 1 500 mm, the wettestwettest monthsmonths beingbeing fromfrom January toto April.April. TheThe average temperature of the hottest month is between 20°20° andand 26°26° C,C, andand thatthat ofof thethe coldestcoldest month between 99 and 16° C, with thethe possibility of below-freezing temperatures iinn thethe uplands inin thethe Southern part of the area. The climatesclimates involved can thus range from moist tropicaltropical in the North to subtropical in thethe South. This species flourishes on deep fertile soils,soils, wellwell-drained- drained but with goodgood waterwater retentionretention properties of metamorphic basalt or granite origin.origin.

Araucaria hunsteinii (Klinki Pine), which has a moremore restrictedrestricted rangrange"e . in Papua New Guinea, betweenbetween 55 andand 10°10° S,S, atat altitudesa l titudes ofof 600600 to 1 500 m.m. The climateclimate isis tropical,tropical, withwith annualannual rainfallrainfal l rangingranging from 11 600600 toto 11 800,800, aa moderatemoderate drydry seasonseason (no(no monthmonth withwith R R >> 7575 mm)mm) and average temperatures rangingranging fromfrom 27°27° to 32° C (maxima)(maxima) and from 18° to 19° C (minima). The soilssoils areare heavy-textured,heavy-textured, fairly alklinealkline.silty-clay . silty-clay soilssoils withwith moderatemoderate drainage,drainage, from some whatwhat weathered lacustrian or alluvial deposits of and conglomerates.

Araucarias havehave beenbeen successfullysuccessfully introducedintroduced inin thethe humidhumid savanna of the NiariNiari valley, inin the Congo and in CoteC8te d'Ivoire. On the other hand, in the coastal savanna area near Pointe Noire and those of thethe ChailluChaillu forestforest (Ngouha(Ngouha II region) in the Congo,Congo, thethe soilssoils are tootoo poor forfor successfulsuccessful growth andand Araucaria doesdoes poorlypoorly andand isis susceptiblesusceptible toto plantplant disease.disease.

The wood of thesethese twotwo Araucarias is whitish. Dry density ranges from 0.52 for thethe cunninghamiicunninghamii toto 0.450.45 forfor thethe hunsteinii.hunsteinii. ComparedCompared toto otherother equally resinousresinous woods,woods, it has lowlow shrinkageshrinkage andand goodgood bendingbending andand axialaxial compressive strength. On the other hand, its radial and tangential compressive strengthstrength isis low,low, asas isis itsits durability. These Araucarias cancan thusthus be used for saw-wood,saw-wood, indoorindoor uses,uses, veneeringveneering andand plywoods.plywoods. TheThe longl ong fibres,fibres, also suit Auricaria forfor paperpaper manufacturingmanufacturing purposes.purposes .

SILVICULTURAL RULESRULES

The development ofof AraucariaAraucaria plantationsplantations outsideoutside theirtheir natural rangerange is hindered firstfirst ofof allall byby seedseed preservationpreservation andand transportationtransportation problems.problems. For example,example, the germinationgermination rate of thethe seedsseeds ofof AraucariaAraucaria hunsteinii decreases by 10 percent each week during the first month, and is nil after eight weeks'weeks ' storage atat room temperature. However, seedsseeds storedstored inin sealedsealed bags at 33 oror 4° C retainretain a germination raterate of 5050 percentpercent afterafter 1818 months.months. Cold-storage long-distance transporttransport isis thusthus essential.essential. -- 137 --

ToTO overcome this difficulty, propagation by cuttings has been experimentally studied inin thethe Congo,Congo, but it isis trickytricky and does not seemseem suitable forfor large-scalelarge-scale use.use.

In the nursery, thethe seedsseeds areare sownsown onon aa well-shadedwell-shaded seedbed,seedbed, atat lowlow seed densities toto allowallow forfor 44 months of growth. After pricking out, thethe plants are kept inin thethe nursery forfor 88 months; thethe saplings planted out at the age of one year areare betweenbetween 2020 andand 6060 cmern high.high.

The planting densitiesdensities rangerange fromfrom 11 600600 toto 11 100100 plantsplants perper hectare,hectare, i.e. spacing ofof 2.52.5 x 2.52 . 5 m to 3 xx 3 m.m. TheThe initialinitial growth-rategrowth-rate is fairly slow and the plantsplants requirerequire assiduousassiduous carecare forfor thethe firstfirst 33 years.years.

The plantationsplantations are stillstill tootoo youngyoung toto provideprovide anyany silviculturalsilvicultural models, but thethe followingfollowing results,results, obtainedobtained inin thethe CongoCongo with treestrees agedaged 1010 1/2 years, shouldshould bebe noted:noted:

Araucaria Araucaria cunninghamii hunsteinii

Ht (m)(m) 15.3 14.8

C 1.501. 50 (cm)(em) 52 49

G (m2/ha)(m2 / ha) 22 15.8

V (m3/ha)(m3 / ha) 168 118

Plantations established on goodgood soil,soil, in thethe NiariNiari Valley,Valley, show satisfactory growth. Some problems havehave arisenarisen withwith parasitesparasites onon dominateddominated trees in particularly dry years, but they recover with a return to normal weather.

5 - PRODUCTIVITY CHARACTERISTICSCHARACTERISTICS

5.1 -- The principalprincipal speciesspecies

5.1.1 - Yield volume

Volume tablestables areare availableavailable forfor thethe principalprincipal speciesspecies currentlycurrently usedused for reforestation purposes.purposes. The diameters are expressed in metres and thethe volumes inin cubiccubic metres.metres. - 138 --

These tablestables referrefer toto mainmain stemstem volume,volume, correspondingcorresponding to a cross-cross­ section diameterdiameter ofof 77 cm.em.

Species Volume tables Validity limitslimits Main stem volume ((Diameter)Diameter)

Tectona grandis V =~ 0.04560.0456 - 1.23561.2356 D + 11.801111.8011 D2 1O-50cm10 - 50 cm (Teak)

TTerrietiaerrietia utilis V =~ 0.0230.023 - 1.1361.136 D + 14.52614.526 D2 10-1O-50cm 50 cm (Niangon)(Niangon)

Nauclea diderrichii V =~ 0.2350.235 ++ 1.9021.902 DD ++ 4.316 4.316 D2D2 1010- - 40 cmem (Sadi)(Badi)

Khaya ivorensisivorensis V =~ 0.4660.466 + 2.7942.794 D ++ 5.9645.964 D2D2 1O-85cm10 - 85 cm (Mahogany)

Terminalia ivorenivorensissis V =~ -- 0.03820.0382 ++ 8.0938.093 D2D2 10 -- 25 emcm (Frami(Framiré)rt! ) V =~ -- 0.041560.04156 ++ 14.5062 14.5062 D2D2 25-70cm25 - 70 cm

Terminalia superba V =~ 0.0240.024 -- 1.1261.126 D ++ 13.52113.521 D2D2 1010- - 5555 cmem (Frake)(Fraké)

Triplochiton scleroxylon V =~ 0.0900.090 -- 1.9081.908 D ++ 13.52113.521 D2D2 10 - 40 cmem (Samba)

CedreCedrelala odorata V =~ 0.03640.0364 ++ 7.353 7.353 D2D2 101O-60cm - 60 cm (Cedrela)(Cedrela)

Pinus caribea V =~ 0.0280.Q28 -- 0.9460.946 D ++ 10.503 10.503 D2D2 101O-45cm - 45 cm (Pine)(Pine)

PinusPinus oocarpa V =~ 0.0170.017 -- 0.6090.609 D ++ 8.158 8. 158 D2D2 10lO-45cm - 45 cm (Pine)(Pine)

Gmelina arborea V =~ 0.0090.009 -- 0.6510.651 D ++ 9.447 9.447 D2D2 10to-30cm - 30 cm (Gmelina)(Gmelina) V =~ 0.1850.185 + 8.909D28.909 D2 3030-60cm - 60 cm

The vovolumelume yield isis inin relation to the characteristics of the stand at the end of the rotationrotation cycle.cycle. - 139 -

STRASTRATIFICATIONTIFICATION AND MMIXIX MMETHODSETHODS

MEMETHODTHOD 11 MI_ PrincipalPrincipal species species t::J=3 Accompanying Accompanying species species •

METMETHODHOD 2

_I= SpeciesSpecies 1 1 t==7c::l SpeciesSpecies 22 - 140 --

5.1.25 . 1.2 - Characteristics ofof thethe principalprincipal speciesspecies atat endend ofof rotationrotation

For economic reasons the forestforest manager may considercons ider reducingreduc ing the length of thethe rotationrotation cycle.cycle . As anan indication,indication, the rotationrotation andand thethe main stem volumevolume at harvest have been calculatedcalculated for differentdifferent exploitableexploitable diametersdiameters..

Rotation (in years)years) Standing main stemstem Mean increment inin relationrelation toto thethe volume in relationrelation toto (m3/ha/year)(m3lha/year) of Reforestation exploitable diameter the exploitableexploitable diameterdiameter stand species (1-1WV(HWV in in m3lha)m3/ha)

404() cmom 50 cmem 60cm60 cm 40 cmem 50 cmem 60 cmem

TeetonaTectona 25 35 50 220 320 350 5 grandis (Teak) 4545 65 85 250 360 400 1100

Aucoumea 25 30 35 300 350 400400 9 KJainKlaineanaeana (Okoutn6)(Okoume) 30 35 45 350 400 450 14

Tarrieta 35 45 - 300 400 - 6 utilis (Niangon) 45 55 - 400 500 - 11II

Nauclea 20 25 35 150150 300 350 9 diderichiididerichii (Bad(Badi) i) 2525 35 45 200 350 400 14

TenninaliaTerminalia 20 30 35 180180 200 775225 7 ivorenivorensissis . (Framire)(Framiré) 3030 40 45 220 250 275 II11

TenninaliaTerminalia 1515 20 25 130130 225 275 8 supesuperbarba (Frake)(Frak6) 20 25 35 220 275 325 14

TriplochitTriplochitonon 16 22 30 200 250 300 8 scleroxyscleroxylonlon (Sa(Samba)mba) 2277 30 40 250 300 350 14

CedreCedrelala 12 1717 25 180 200 250 10 odorata (Ccdrela)(Cedrela) 17 ls25 30 220 250 300 18

GmclinaGmelina 15 2020 - 225 275 - IIl 1 arborea (Gmel(Gmelina)ina) 20 2525 - 275 325 19

The upper figure indicates the minimum rotation for standing main stem volume and itsits mean increment.increment.

The lolowerwer figure indicatesindicates thethe maximummaximum valuesvalues forfor thethe samesame parameters.parameters.

The variations inin mean volumevolume incrementincrement atat aa givengiven ageage shouldshould bebe noted:noted: they reveal thethe effecteffect ofof sitesite conditionsconditions andand standstand treatmentstreatments onon standstand growth. In particular, this effectef fect could be quantifiedquantified indirectly byby analysing the yieldyield tables.tables. The values mentioned above areare indicativeindicative andand only provide orders ofof magnitude.magnitude. - 141 --

Moreover, thethe choicechoice ofof exploitable diameter affectsaffects thethe timbertimber volume (cut at 30 cm)em) available when the stand reaches the mean dimensions established by the forestforest manager.manager.

IInn the case of Framir6,Framire, the followingfollowing values areare obtained:obtained:

for the availableavailable timber volume inin relation to exploitableexploit able diameter,d i ameter,

for the ratio of timbertimber volumevol ume (TV)(TV) toto mainmain stemstem volume,volume, asas thethe volume indicated inin volumevolume tables is inin factfact veryvery oftenoften thethe mainmain stem volume (MS).(MS).

Exploitable 40 cmem 50 cmem 60 cmem diameter

Timber volumevolume (TV)(TV) 100/140 210/250 300/340 m3/ha

TV/MS (as(as percent)percent) 70 85 95

With reference toto Mahogany,Mahogany, thesethese valuesvalues become:become:

ExpExploitableloitable 40 cmem 50 cmem 60 cmem diameter

Timber volumevolume (TV)(TV) 100/110100/110 170/190 270/300 m3/ha

TV/MS (as(as percent)percent) 76 88 96

The provisionalprovisional estimates of thethe influenceinfluence ofof exploitableexploitable diameterdiameter (exp(exp.. diam.)diam.) onon the timber volume loggedlogged per hectarehectare inin thethe finalfinal harvestharvest (clear felling) are as follows:follows:

Exp. FramireFramir6 FrakéFrake Samba Mahogany Okoume"Okoume diam.

Timber/volume 50 cmem 230 230 230 190 320 in m3/ha 60 cmem 320 320 310 270 400

Mean incrementincrement 50 cmem 8.5 10.6 9.4 5.7 10 in timber 60 cmem 9.1 1010.8. 8 10.3 6.7 10 volume (m3/ha/year)

These values are of course merely indicative,indicative, butbut theythey makemake itit possible to show the effect of an economic option (exploitable diameter) on dendrometric parameters such as the timber volume available at thethe timetime ofo f harvest. - 142 -

5.2 -- Thinning products

Withwith regardregard toto thinningthinning products, exceptexcept inin thethe cast of speciesspecies with dense wood of good durability (Teak,(Teak, Badi) which can be usedused forfor fuelwoodfuelwood andand construction (building(building poles),poles), the chief potential usesuses forfor most of thethe species are asas postsposts andand smallsmall diameterdiameter saw-wood.saw-wood. The minimum all-over diameterdiameter requiredrequired forfor saw-woodsaw-wood isis approximatelyapproximately 2525 cm.ern.

The chief problems encounteredencountered in sawingsawing trialst rials on thinnedthinned timberstimbers areare::

loloww diameter ofo f thethe wood;wood; a high percentagepercentage ofo f sapwood;sapwood; a highhigh raterate ofof youngyoung woodwood withwith veryvery heterogeneousheterogeneous physical and mechanical properties;properties; low density;

the presencepresence ofof defects:defects: blackblack spots,spots I internal growthgrowth strains,strains, frequent knots.knots.

Some ofof thesethese drawbacksdrawbacks cancan bebe attenuatedattenuated byby usingusing selectedselected andand improved pplantlant stock, by adequateadequate ssilviculturalilvicu ltural practices (seedling(seedling selection,selection, prunings),prunings) I andand thethe useuse ofof sawingsawing equipmentequipment andand techniquestechniques suitedsuited toto thisthis typetype of wood.wood.

The technological trialstrials on plantation wood (DURAND(DURAND 19851985)) show thatthat thethe technologicatechnologicall characteristicscharacteristics ofof plantation-grownplantation-grown woodwood moremore oror lessless 1515 yearsyears old are slightlyslightl? inferiorinferior toto thosethose ofof naturalnatural forest-grownforest-grown wood.wood.

Natural forest/Plantationforest/Planration PPlantationlanration (N.F.) ((P)P)

FramiréFramire FrakeFraké Samba CedreCedrelala PPinusinus PinusPinos GGmelinamelina Teak N.F.N. F. PP.. N.F.N. F. P.P. N.F. P. carib. oocar.

Densi[),Density 0.51 0.42 0.57 0.40 0.40 0.36 0.30 0.45 0.53 0.480.48 0.65

VolumetricVolumetric 12.912.9 11.5 9.8 9.7 11.3 11.11.77 12.5 9.29 ? 8.1 sshrinkagehrinkage (%)

NervosNervosityity 0.36 0.37 0.47 0.43 0.37 0.36 0.32 0.40 0.41 0.44 0.35 (%)( %)

Vs -- VO VolumetricVolumetri c shrinkageshrinkage -= ------X 100%100\ VO where VO:VO : Anhydrous vovolumel ume VsVs:: Volume ofof a samplesample passingpassing fromfrom thethe anhydrousanhydrous toto thethe saturated state.state.

Nervosity: Volumetric shrinkage/moisture content of the woodwood at. saturation point - 143 -

With regard to the mean dimensions of thinning products,products, the following figures are indicativeindicative (DUPUY(DUPUY 1988):1988) :

N: Number of stems/hastems/ha harvestedharvested inin thinningthinning operationoperation

D: Mean diameter, inin cm,em, ofof thethe standsstands priorprior toto thinning.thinning. TheThe meanmean diameter of thethe stemsstems harvestedharvested inin thethe thinningthinning operationoperation isis slighltly lessless than that of thethe standstand prior toto thinning.thinning.

V: Mean main stemstem volumevolume (in m3jham3/ha)) of the thinningthinning harvest.harvest. The figure for this volume is given only when thethe thinningthinning products are big enoughenough toto bebe usedused forfor constructionconstruction woodwood oror timber.timber.

SpeciesSpecies ThinningThinning-out-out oror 1stI st thinning 2nd thinningthirining 3rd3rd thinnithinnin igg

N D VY N D VY N D VY

Aucoumea klaineanakJaineana 600 - - 150 17 - 80 29 70 (Okoume)(Okoumé)

Tarrietia utilisutilis 250 - - 350 15 - 175 21 -. (Niangon)

TerminabaTenninalia superbasuperba 380 (10)(10) 20 160 181H 4040 6565 26 45 (Frake)(Fraké)

Terminalia ivorensisivorensis 360 (10)(!O) 25 175 1188 4040 8080 25 45 (Framire)(Framiré)

Triplochiton 300 - -- 175 1122 - 90 2121 40 sc1eroxylonscleroxylon (Samba)

Cedrela odorata 600 - 40 275 15 50 120 23 55 (C(Cedrela)edrela)

PinuPinuss (Pine) 500 9 - 300 1122 - 200 23 100

In the case of Teak, in relation toto thethe thinning products'products' dimensionsdimensions and conformation, thethe followingfollowing usesuses cancan bebe envisagedenvisaged (DURAND,(DURAND, 1984):~984):

Diameter: < 10 cmem 10 - 1414 emcm 15 - 21 cmem 25 - 35 cmem > 35 cmem

Length: < 3 m 3 - 4 cmem 8 - 18 m > 3 m > 3 m

Use: stakes poles posts saw-woodsaw-wood saw-wood,saw-wood, cabinet- making, slicing

The term "saw-wood"rrsaw-wood rr comprises products suchsuch as planks, boards, rafters and battensbattens.. - 144144 -

For this species,species, thethe productsproducts obtainable fromfrom thethe various thinningsthinnings are thus as followsfollows (MAITRE(MAITRE H.F.,H.F., 1983):1983):

Thinning (no.)(no.) 1 2 3 4 5 6 7

Mean diameter 11 15 21 2525 30 38 43 (in cm)cm)

Main stemstem wood 25 36 35 39 39 44 36 volume (m3/ha)(m3 / ha)

Fuelwood + + + + + + + + Construction wood + + + + + + + Timber + + + +

+ . possibility of use

5.3 - Rotation periods

At thethe timetime whenwhen treestrees areare planted,planted, thethe desiredesire toto harvestharvest aa cropcrop isis already present.present.

Production reforestationreforestation correspondscorresponds toto thethe intentionintention toto obtainobtain givengiven categories of wood productsproduc ts atat maturity.maturity.

It is importantimportant toto foreseeforesee different exploitable ages in relation to the objectives established byby thethe forestryforestry plan.plan.

The optimization of the logginglogging age depends upon technical, silvicultural andand financialfinancial criteria.criteria.

InIn thethe presentpresent context,context, the aimaim ofof intensiveintensive reforestationreforestation projectsprojects is the quickquick implementation ofof successivesuccessive harvestharvest thatthat willwill makemake itit possiblepossible toto relieve the pressure onon natural forests, with a view to rationalizing their exploitation andand ensuring theirtheir continued existenceexistence throughthrough adequateadequate planning.planning.

Exploitable age isis considered here from the standpoint of optimizing the relationshiprelationship between timber volumes/silviculture andand profitabilityprofitability (DUPUY,(DUPUY, 1987)1987). .

5.3.1 - Ratio of exploitable diameter toto usable volumevolume

In the early stages, it is important to seek to exploit the greatestgreatest ppossibleo ssible amount ofof thethe timbertimber capitalcapital produced. The stem volume is generallygenerally consideredc onsidered equivalent toto mainmain stemstem volume.volume . When timber isis the objective, itit is generallygenerally prudent toto limitlimit thethe small-endsmall-end sectionsection toto aa diameterdiameter ofof 2525 cm.em. - 145 --

It is thus possible toto evaluateevaluate the volume of usable timber by means of the small-endsmall-end sectionsection volume/mainvolume/main stemstern volumevolume ratio.ratio.

Small-end cutcut volumevolume Diameter atat 1.301.30 mm (in(in cm)em)

Main stem volume 35 40 45 50 55 60

25 cmem cuteut FrakéFrake Gmelina 82% 89% 92% 92% 93% 93% Cedrela 64% 80% 91% 93% 94% 95% 74% 79%791; 83% 87% 90% 94%941;

30 cmem cuteut

FrakeFrak6 64% 76% 83% 881;88% 91% 93% Gmelina 41% 61% 751;75% 84% 90% 90%901; Cedrela 61% 671;67% 72% 76% 79% 82%821;

withWith a 25 cmem small-end cut, it is necessary toto avoid settingsetting exploitable diameters of lessless thanthan 40 -- 45 cmem so as to ensure that at leastleast 80 percent of thethe stemstem volumevolume willwill bebe usable.usable.

5.3.2 -- RatioRat-io ofof exploitableexploitable diameterdiameter toto numbernumber ofof thinninqsthinnings

The silvicultural rulesrules havehave inin any case been formulated so as to limitlimit inter-tree competition byby thinningthinning whilewhile maintainingmaintaining aa steady pacepace of individual growth.

Commercial Teak thinning products - 146 --

Regular thinning isis therefore indispensable.indispensable . The number of thinnings depends on thethe exploitableexploitable diameter.diameter.

Species Exploitable diameter Number of thinningsthinnings

Teak 30 cmem 3 40 cmem 4 45 cmem 5 50 cmem 6

Frab§,Fraké, 40 cmem 2 FramireFramiré 50 emcm 3 Samba 60 cmem 4

Cedrela 40 cmem 3 50 emcm 4 60 emcm 5

To obtain anan exploitableexploitable diameterdiameter ofof 5050 cm,em, oneone mustmust plan.plan.

- 6 thinnings forfor Teak,Teak,

- 4 thinnings forfor Cedrela,Cedre!a, - 3 thinnings forfor Fraké,Frake, FramiréFramire andand Samba.Samba.

If the exploitable diameter is to be 60 emcm one extra thinning should be planned toto reducereduce inter-treeinter-tree competition.competition.

5.3.3 -- Ratio of exploitableexploitable diameterdiameter toto averageaverage exploitableexploitable ageage

For correctly managed standsstands and averageaverage sitesite fertilityfertility thethe averageaverage time required toto reachreach exploitableexploitable diametersdiameters cancan bebe calculated.calculated.

speciesSpecies Exploitable Length of cycleeyele diameter

Teak 40 cmem 35 years 45 cmem 45 years 50 emcm 55 years

FrakéFrake 40 cmem 16 years 45 cmem 20 years 50 cmem 25 years 60 cmem 35 years

FramiréFramire 40 emcm 20 years 45 cmem 25 years 50 cmem 35 years 60 cmem 45 years

5.3.4 -- Exploitable diameterdiameter andand profitabilityprofitability

Without knowing thethe sellingselling priceprice forf o r plantationplantation woodwood itit isis difficultdifficult to make accurate estimates.estimates. By way of indication, ifif aa value ofof 1010 percentpercent is ascribed toto the internalinternal returnreturn raterate forfor anan exploitableexploitable diameterdiameter ofof 5050 cmcm for Fraké,Frake, the following isis obtained:obtained : - 147 --

Exploitable diameterdiameter Rate of return

40 cmern 4% 50 cmern 10% 60 cmern 8%

In the case ofof Teak,Teak, if the value of 1010 percentpercent isis ascribedascribed toto thethe internal rate of returnreturn forfor aa diameterdiameter ofof 4545 cm,em, thethe resultresult is:is:

Exploitable diameterdiameter Rate of returnreturn

40 erncm 4 %% 45 erncm 10 % 50 erncm 8.5 %

5.3.5 - Rotation recommendationsrecommendations

In thethe casecase ofof speciesspecies withwith medium-lengthmedium-length rotationrotation cyclescycles (Fraké,(Frake, Framiré,Framire, Samba, Gmelina,Gmelina, Cedrela):Cedrela):

The exploitabexploitablele diameter must be at least 40 emcm toto limitlimit commercialcommercial losses ono~ thethe stemstem volumevolume produced;produced;

An exploitable diameterdiameter inin excessexcess ofof 50SO cm,em, wouldwould requirerequire anan extraextra thinning.

Over 50 erncm inin exploitableexploitable diameter,diameter, the requiredrequired additionaladditional rotation time does not give riserise toto anyany additionaladditional profit.profit.

For Teak, anan exploitableexploitable diameter of 45 cmem isis thethe bestbest compromisecompromise between profit andand yield.yield.

Insofar as the goal isis to enhance the return on timber and avoid the very large diameters thatthat wouldwould protract thethe rotationrotation cyclecycle forfor no additional financial benefit, itit isis reasonablereasonable toto adoptadopt anan exploitableexploitable diameterdiameter ofof 4545 -- 50 cmcm forfor medium-rotationmedium-rotation speciesspecies and ofof 4040 - 45 cm forfor Teak,Teak, onon fertilefertile sites. On sitessites withwith poorpoor fertilityfertility itit is necessarynecessary to adoptadopt smallersmaller exploitable diameters soso asas toto avoidavoid excessivelyexcessively protractingprotracting thethe cyclecycle andand allow the rapid conversionconversion ofof thesethese ratherrather unproductiveunproductive stands.stands.

Species Fertility Exploitable Exploitable diameter age

Teak Excellent 50 cmern 45 years Medium 45 cmern 50 years Poor 40 cmern 65 years

FrakeFrak6 Excellent 50 cmern 18 years Medium 45 cmern 22 years Poor 40 cmern 25 years Bad 35 cmem 25 years

FramireFramiré Good 45-50 cmern 25-30 years Cedrela Good 45-50 cmern 18-22 years Samba Good 45-50 cmern 25-30 years Gmelina Good 45-50 cmern 15-20 years - 148 --

The choice of exploitable ageage is subject to the following constraints:

- Technical: toto obtain,obtain, inin aa given time, the largest possiblepossible quantity of wood suitablesuitable forfor timber;timber;

Financial: for timber one must seek to achieve anan optimum rate of return;

Silvicultural: to avoid too many thinnings in mature stands, so as to preserve thethe standstand andand simplifysimplify management.management.

In the presentpresent state of the art, the followingfollowing exploitable ages can be foreseen forfor properly-managedproperly-managed standsstands ofof mediummedium fertility:fertility:

Species Exploitable diameter Explotaible

Gmelina 50 cmem 15-20 years Frak6Frake 50 cmem 20-25 years Cedrela 50 cmem 20-25 years Framir6Framire 50 cmem 30-35 years Samba 50 cmem 30-35 years Teak 45 cmem 50-60 years

6 - MIXEDMIXED STANDS

The idea.of associating species,species, mostmost oftenoften two,two, onon plantations isis anan old one.one. The object was toto attemptattempt toto solve,solve, or atat leastleast simplifysimplify thethe silvicultural (pruning, shape ...)... ) and plant protectionprotection (borers,(borers, psyllids,psyllids, ...... ) ) problemsproblems inherent inin singlesingle speciesspecies plantations.plantations.

Ever since the first line enrichment and forest underplantinunderplantingg operations, silviculturalists have attempted associations of Niangon,Niangon , Mahogany, Sipo,Sipo, Makoré,Makore, Framiré,Framire, Okoumé,Okoume, etc.etc. Recently, with the development of whollywholly exposed plantations, different associations havehave been attempted with Teak, Framiré,Framire, Mahogany,Mahogany, Fraké,Frake, Cedrela,Cedrela, Samba,Samba, Gmelina,Gmelina, etc.etc.

These trialstrials suggest two modesmodes ofof associationassociation in relationrelation toto thethe silvicultural characteristicscharacteristics of of thethe speciesspecies toto bebe associatedassociated inin mixedmixed stands.stands.

6.1 -- Ways of associatingassociating twotwo speciesspecies inin mixedmixed standsstands

6.1.1 -- CreationCreation ofof aa two-storeytwo-storey standstand

The object isis toto createcreate aa two-storeytwo-storey standstand consistingconsisting of a principal species to be given priority inin silviculturalsilvicultural operationsoperations andand anan accompanyingaccompanying species whose rolerole isis primarilyprimarily silvicultural.silvicultural . This two-tieredtwo-tiered structure,structure, determined byby thethe intrinsic characteristics ofof thethe species concerned, changes in relation to the silvicultural treatmentstreatments applied.applied.

Depending uponupon thethe silviculturalsilvicultural characteristicscharacteristics ofof thethe principalprincipal species, the characteristics of the accompanying species may differ considerably:

If the principalprincipal speciesspecies is sun-loving and hashas a fast initialinitial growth-rate, thethe accompanyingaccompanying speciesspecies forms:forms: - 149 --

either a permanentpermanent oror temporarytemporary sub-storeysub-storey playingplaying aa trainingtraining role (stem(stem formation,formation, pruning)pruning)

or an accompanying standstand toto fillfill inin whichwhich willwill thenthen bebe harvestedharvested during thethe firstfirst thinningsthinnings (cover(cover formation).formation) .

The role of thethe associatedassociated speciesspecies isis inin realityreality oftenoften aa mixedmixed one:one: training andand filling-in.filling-in.

Principal species + Accompanying species

Samba + TeakTeak (training(training role)role) Sipo + NiangonNiangon (accompanying (accompanying role)role) Mahogany + NiangonNiangon (mixed(mixed role:role: training/filling)training/filling)

If the principal speciesspecies

. either cannot be plantedplanted in mono-speciesmono-species stands for plant protection reasonsreasons (Mahoganies)(Mahoganies)

. or has a slowslow initialinitial growthgrowth raterate (Sipo),(Sipo) I

the role of the accompanying speciesspecies isis inin this case to take the place of thethe naturalnatural regrowthregrowth duringduring thethe firstfirst yearsyears followingfollowing planting,planting, as a formation whose growth isis controlledcontrolled byby thethe silviculturalist.silviculturalist .

Throughout thethe firstfirst phase ofof standstand growth, the accompanying speciesspecies is dominant and thethe principalprincipal speciesspecies isis dominated.dominated.

The importance of the accompanying species gradually and progressively decreases to the advantage of thethe principal species, of which only the best individuals are preserved, however,however, duringduring thethe thinning operations: thethe finalfinal stand is a two-storey single-treesingle-tree mixturemixture ofof thethe twotwo species.species.

6.1.2 - CreationCreation of a single-storey stand

The object is to create a synergy between two species whose silvicultural importanceimportance isis identical.identical.

The aim of this typetype of association isis thus to obtain, at thethe end of the rotation cycle, a single-storey formationformation where twotwo species grow together in clumps,clumps, or inin aa single-treesingle-tree mixturemixture wherewhere bothboth reachreach thethe exploitableexploitable diameter simultaneously.s imultaneously.

Under thesethese conditions,conditions, the twotwo speciesspecies mustmust havehave similarsimilar growthgrowth patterns and silvicultural rules,rul es, inin particular with regard to the following parameters:

planting density

manner and intensivenessintensiveness ofof thinningthinning outout andand thinningthinning operationsoperations (stand age,age, numbernumber ofof stems to be removed, basal area, operation limit) -- 150150 --

number of operations

length of rotation cyclecycle

Species 11 + Species 22

FramireFramir6 + FrakeFraké FrakeFraké + Samba

When a species of economic interestinterest isis vulnerable to adverse weather conditions, disease or otherother factorsfactors (for example Framir6),Framire!) I the foresterforester engages in mixmix plantingplanting (such(such asas FramiréFramire ++ Fraké)Frake) to reduce the riskrisk ofof failure by combining:combining :

a targettarget oror mainmain speciesspecies (Framiré),(Framire),

a secondary speciesspecies (Fraké).(Frake)

Thus, if the main species fails to grow satisfactorily, thethe mix can be converted into a single-species stand of the secondary species. This option is only used, of course,course, asas aa lastlast resort.resort.

6.2 - Comparative growth andand compatibilitycompatibility ofof mixedmixed speciesspecies

It appearsappearS that thethe compatibilitycompatibility of twotwo mixedmixed speciesspecies is linkedlinked toto temperament.temperament . TheThe twotwo associatedassociated speciesspecies mustmust bebe ableable toto toleratetolerate eacheach other.other. In particular,particular, if their initialinitial growth isis different,different, thethe speciesspecies withwith thethe slowest growth mustmust toleratetolerate beingbeing dominated.dominated.

Teak/FrakéTeak/Frake mix (aged(aged 33 years); TENETENE forestforest - 151 -

SILVICULTURAL AFFINITIES OF REFORESTATIONREFORESTATION SPECIESSPECIES

NIANGON ------""- -- " ""- -- ""- ""- ""- ""- "'- ""- ""­ OKOUME "'-

'" "- "'" "­ "- SAMBA Increase in initial growth-rategrowth ~ rate and thinningthinning frequencyfrequency '--1 1 --- ___ FAAMIAEFRAMIRE • 1 -- _ FRAKEFAAKE ______LI ______--- ~-- _

LowLow interindividualinterindividual competitioncompefition thresholdthreshold and early hierarchization

1 --1 __ ------I CEDRELACEDAELA __ - I - GMELINAGMELINA ./--- 1 ./ I 1 .// I ./ PINES I ---./ ./'1I ------././ 1

TEAK /./ --- 1I - 152 -

At thethe presentpresent time,time, thethe speciesspecies usedused forfor reforestationreforestation purposespurposes areare sun-loving; when they are dominated by others their growth is greatly slowed down. Keeping themthem inin thisthis statestate can,can, inin thethe end,end, leadlead toto theirtheir elimination.elimination. However, somesome ofof thesethese speciesspecies cancan toleratetolerate aa certaincertain amountamount ofof cover.cover. Two types of speciesspecies standstand outout thisthis regard:regard:

Exclusively dominantdominant species:species: Framiré,Frarnire, FrakeFraké Samba, Gmelina, Cedrela, Pines, OkoumeOkoumé

Species thatthat cancan toleratetolerate a certain amountamount ofof cover:cover: Niangon, Teak, Mahogany, SipoSipo

In associating twotwo speciesspecies withwith thethe objectobject ofof creatingcreating aa two-storey,two-storey, principal species/accompanyingspecies/accompanying speciesspecies standstand (mode 1) it is possiblepossible toto associate:

as thethe accompanyingaccompanying species,species I those that can toleratetolerate a certaincertain amount of cover;cover;

as the principalprincipal partner, a species with fasterfaster growthgrowth thanthan theaccompanying species,species, asas thethe principal speciesspecies remains dominant.dominant.

In this case, the silvicultural operations will be performed for the benefit ofof thethe dominant species.species. The role of the accompanyingaccompanying species remains subordinate at allall timestimes toto thatthat ofof thethe principalprincipal species.species.

The association ofof twotwo speciesspecies inin a single-tree mixture must meet thethe following criteria:criteria:

their growthgrowth patternspatterns mustmust bebe similar,similar I in orderorder toto checkcheck thethe appearance of aa dominant/dominateddominant/ dominated state;state;

their social behaviour (competition(competition thresholds)thresholds) andand thinningthinning regimeregime (number andand intensiveness) must be compatible;compatible;

silvicultural treatment must be thethe samesame forfor both species.species.

A silviculturalsilvicultural affinitiesaffinities trialtrial (A.C.P.) to classifyclassify thethe variousvarious species reveals aa very markedmarked partitionpartition ofof thethe speciesspecies inin thethe mainmain storey.storey.

It is based onon thethe followingfollowing criteria:criteria:

mean height incrementincrement (between(between the ages of 1 and 10 years),years) I which determines thethe stands'stands' futurefuture stratification;stratification;

social behaviour, which isis quantified by the basal area thresholds above which individualsindividuals beginbegin toto compete;compete;

planting density, thethe valuevalue ofof whichwhich cancan favorablyfavorably influenceinfluence thethe conformation of the harvested stems by fostering pruning, straightness etc.;etc.;

the thinning schedule,schedule, defineddefined soso asas toto ensure optimumoptimum standstand growth.growth.

There isis a very markedmarked partitionpartition ofof thethe speciesspecies inin thethe mainmain storey.storey.

Analysis of the characteristics of the principal axesaxes makesmakes it possible, after interpretation,interpretation, toto distinguish:distinguish: SILVICULTURAL CONSTRAINTS ONON MIXEDMIXED STAND MANAGEMENT

PLANTING 1100 // 15001500 700 DENSITY (stems/ha) I

MEAN HEIGHT INCREMENTINCREMENT AT

AGE 4 YEARS (m/year) 00.5.5 / 11 15 1/2 2 /12.5 3/4 22.5 5/ 3

AGE AT FIRST I THINNINGS (years) 6/86 / 8 4 / 6 4/64 / 6 33/4/ 4 3 / 4

TOTAL NUMBER OF I ~ I I THINNINGS 3 5 3 7 3 3 .... I w'" MEAN HEIGHT I I I INCREMENT AT 1 1/1.5 11.5 5 / 2 1.5 1.5 // 2 1L.5 / 22 22/2.5/ 2.5 2.5/32.5 / 3 22/2.5/ 2.5 AGE 10 YEARS (m/yr)

AGE AT SECOND THINNING (years) 12/15 7 1/9 9 / 11 7/97 / 9 6/86/ 8 5/6 5// 6

LIMIT G FORFOR I I I I I 2ND THINNING 12 20 10// 12 15 16 17 1212113/13 7 (m2/ha)(m 2lha) I I I I I AVERAGE ROTATION ~ 50 30 40 50 25 25 3030 25 25 CYCLE (years)

m Zz 0"O-0 CDOco0 1-< GlG) o0 -ri (Dw j;5 ,.->2 > mm K;:: m "co "co ,.> z "z_Cic gOo0 m o0 ,.> >,. K;:: "" 37 " " CDWEau) c K;:: o) 0Gl " rC m m CD 0 ,.> K;:: z " :;;55 " ,.> z ,.m> m >,. rilt;; m - 154 --

* The socialsocial speciesspecies thatthat rapidlyrapidly becomebecome rankedranked intointo severalseveral tierstiers when interindividual competitioncompetition appears.appears. Dominant subjects emergee~erge in thethe stand withwith the appearance ofof a codominantcodominant tiertier and a dominateddominated tier.tier. The latterlatter twotwo tierstiers consistconsist ofof slow-growingslow-growing individuals who are sooner or later eliminated by their competitors.

In this group twotwo separateseparate entitiesentities standstand out:out:

species with slow to medium initial growth (1(1 to 2m/year) with a long rotation cycle (>( > 35 years)years) andand latelate thinning:thinning: Okoume,Okoum6, Badi and Niangoo;Niangon;

species with rapid initial growth (2(2 to 33 m/year),m/year), medium-lengthmedium-length

rotation (25 to 3030 years),years) I and earlyearly thinning:thinning: Framire,Framir6, Frake,Fraké, Samba.

The silvicultural procedures for the species in this first group are characterized by few thinnings (3)(3) occurring at medium to lowl ow (<« 15 m2/ha) basal area thresholdsthresholds whichwhich cancan bebe consideredconsidered asas competitioncompetition indicators.indicators.

* Species which tolerate heavy competition without the rapid appearance of dominant subjects and distinct vertical ranking.ranking.

In this group the followingfollowing twotwo sub-groupssub-groups cancan be distinguished:distinguished:

species with a medium rotation cycle, fastfast initialinitial growth andand aa fewfew heavy thinnings (3):(3): CedrelaCedrela andand Gmelina;Gmelina;

species with mediummedium andand longlong rotationrotation cyclescycles characterizedcharacterized byby repeated thinnings (5(5 toto 7)7) ofof mediummedium intensity:intensity: TeakTeak andand Pine.Pine.

The silviculturalsilvicultural proceduresprocedures forfor thethe speciesspecies inin this second subgroup are characterized in particular by thinningthinning operationsoperations carriedcarried outout atat highhigh basal area thresholdsthresholds ( > 15 m2/ha).m2 / ha) .

Classification intointo thesethese fourfour sub-groupssub-groups cancan more clearly showshow certain mixed-species affinities.affinities.

The species in the above groups show similarities inin their specific andand social behaviour which,which, however,however, areare notnot sufficientsufficient toto concludeconclude thatthat theythey cancan always be grown inin aa single-treesingle-tree mixture.mixture. ForFor example,example, Teak has aa fasterfaster initial growth rate than Pines and would quickly rise above them, which would consequently alter theirtheir furtherfurther growth.growth.

AsAS regardsregards thethe specialspecial casecase ofof Mahogany,Mahogany, silviculturalistssilviculturalists havehave hadhad recourse to mixed plantingplanting toto trytry toto solvesolve thethe problemsproblems ofof terminalterminal budbud destruction byby borers.borers. These terminal bud attacks do in fact considerably decrease initialinitial growth and cause certain shape problemsproblems (espe(especiallycially forking)forking). .

It appears that when planted in association with species with slow initial growthgrowth (Niangon,(Niangon, Okoume,Okoumé, Badi),Badi ) , some MahoganyMahogany trees,trees, in spitespite ofof attacks, grow sufficientlysufficiently wellwell toto staystay inin thethe dominantdominant storeystorey andand developdevelop well-shaped buttwoodbuttwood thatthat reachesreaches aa lengthlength ofof aroundaround tenten metres.metres. The success of this type of mix, which isis thethe resultresult ofof aa compromisecompromise between:between:

on the one hand, the medium to slow initial growth raterate ofof Mahogany.Mahogany. (When notnot attacked,attacked, it is aroundaround 2 m/yearm/year in height,height, but is in fact reduced by aboutabout halfhalf byby thethe borerborer attacks);attacks) ; - 155 --

and on the other, its association withwith slow-growingslow-growing species (1m/year) whichwhich in the end, through selective thinnings, makes itit possible toto obtain a single-tier stand of the long-rotation species (Badi, Okoume,Okoumé, Niangon) with a few dozendozen MahoganyMahogany trees mixed among themthem.. The final mix depends on the growth and/or shape characteristics of thethe MahoganyMahogany trees.trees. If thethe latterlatter proveprove tootoo disappointing, the final stand will be convertedconverted intointo aa single-single­ species, one consistingconsisting exclusivelyexclusively of thethe long-rotationlong-ro tation speciesspecies associated with thethe Mahogany inin thethe originaloriginal mix.mix.

6.3 -- Silvicultural constraintsconstraints onon thethe creationcreation ofof mixedmixed standsstands

The characteristiccharacteristic behaviour of each species gives rise to a set of silvicultural constraintsconstraints applyingapplying toto mixedmixed stands.stands.

If the reforestation managermanager decidesdecides toto plantplant aa mixmix ofof twotwo species, he must ensure thatthat thesethese species:species:

have identical ecologicalecological requirements;requirementsi

are species with similarsimilar plantingplanting densities;densities;

have compatiblecompatible growthgrowth andand silviculturalsilvicultural characteristics.characteristics.

FrakéFrake FramireFramiré Samba Cedrela Gmelina Teak Pine Badi OkouméOkoume

Fl1IkeFraké

FramireFramiré +/0

Samba +/0+10 +/0+10

Cedrela · · ·

Gmelina 0 0 +/0+10 +/0+10

Teak 0 0 0 0 +/0

Pine ·- · · · · · , Badi · · · ·- · · ·

OkoumeOkoumé · · · · · · -· +/0+10

Niangon · ·- · · · · · 0 0

+ : The two speciesspecies cancan bebe growngrown togethertogether in aa single-treesingle-tree mixture without favouringfavouring oneone overover thethe other.other.

oO : The principal speciesspecies mustmust bebe chosenchosen priorprior toto plantingplanting or,or, at lalatest,test, at the time of the first thinning-out operation soso asas toto definitivelydefinitively establish the stand's vocation atat anan earlyearly stage.stage. As a rule,rule, thethe principal speciesspecies isis thethe one with thethe most rapidrapid initial growth.

: Association toto bebe avoided.avoided. - 156 --

+Rpa

Niangon/Badi mix (aged(aged 33 years);years); YapoYapo forestforest

The principalprincipal mixes thatthat cancan atat presentpresent bebe recommendedrecommended areare the following:

Principal species/accompanyingspecies / accompanying speciesspecies mixturemixture

Framiré/Teak:Framire/Teak: Teak is the accompanying species: it can tolerate Frak6/TeakFrake/Teak a certain amountamount of cover in this role.role . Its Samba/Teak growth, relatively slowerslower than that of the main Cedrela/TeakCedrela/ Teak species considered here, relegates it to the Gmelina/TeakGmelina/ Teak dominated storey.storey . These mixes, which are suitable for use essentiallyessentially in thethe moistmoist semi-deciduoussemi-deciduous forest zone, may evolve inin thethe pre-forestpre-forest zonezone towards a single-tree mixture asas thethe growthgrowth ofof thethe so-called principalprincipal species slows sooner than Teak, which cancan thusthus catchcatch upup withwith them.them.

Mahogany/Niangon:Mahogany/ Niangon: This mix, suitable for use in the moistmoist evergreen forest zone,zone, evelevolves yes as timetime passes.passes. Certain Mahogany trees, dominated whenwhen young, may in spite of borer attacks catch up with thethe NiangonsNiangons andand rise above themthem asas thethe standstand growsgrows older.older. The stand evolves towards a single-tree mixture of a few Mahoganies in a standstand predominantlypredominantly composedcomposed of Niangons. SingleSingle-tree- tree mix

Framire-/Frak6:Framire/ Frake: This mix, suitablesuitable only forfor thethe moistmoist evergreenevergreen forest/semi-deciduous closedclosed forestforest transitionaltransitional zone, must be treated so as to favour the FramiréFramire by late thinning.thinning. - 157 --

Frake-/Samba:Frake/Samba: This mix,mix, suitable for thethe moistmoist semideciduoussemideciduous forest zone only, may be mademade to favour the Sambas by earlyearly thinning.thinning.

Framiré/Samba:Framire/Samba: This mix, which has not yet been tested, could be used inin thethe moistmoist evergreenevergreen forest/moistforest / moist semi-semi ­ deciduous forest zone. Late thinning should favour thethe Framir6.Framire.

Badi/Mahogany: This mix,mix, already successfully used in CentralCentral Africa, should be managedmanaged soso asas to favourfavour thethe Mahoganies whenwhen theythey areare growinggrowing well;well; otherwise,otherwise, the Mahoganies are tot o bebe eliminated.eliminated.

Cedrela/Gmelina: This mix, which can be used throughoutthrougho ut the closed forest zone, must be managed so as notnot to penalizepenalize the Gmelinas, whose initial growth-rate is slower than that of the Cedrelas: late thinning is recommendedrecommended..

Samba/Gmelina:Samba/ Gmelina: This mix isis toto be used in the moist semi-decidous forest zone, where late thinning will favourfayour thethe Gmelinas.

If thethe reforestationreforestation managermanager decidesdecides tot o associateassociate inin aa single-treesingle-tree mixturemixtu re aa speciess p e cies whosewhose initialinitial recommendedrecommended densitydensity is 5500/70000 / 7 0 0 stems/ha/stems/ hal priprincipalncipal species)species ) with with aa secondarysecondary speciesspecies forf o r which 1 1001 00 - 1 500 stemsstems/ha/ ha is recommended, thethe densitydensity adoptedadopted forfor thethe mixmix mustmust bebe thethe highest,highest, i.e.i.e. 1 100100/1/ 1 500500 stems/ha.stems/ ha.

If the mix isis effected byby alternatingalternating rowrow byby row,row, withwith anan intervalinterval ofof 33.75. 75 m between rowsrows (to allowallow mechanizedmechanized upkeep),upkeep), the principal species isis planted at intervalsintervals ofof 3.753.75 m along the row and the accompanying species at intervals of 2/2.52 / 2 . 5 m m alongalong thethe row.row.

In thisthis case,case, thethe accompanyingaccompanying species basically playsplays aa training role,role, keeping regrowth under controlc ontrol and trainingtraining thethe treestrees belongingb e l o nging toto thethe principal species.species.

However, at the endend ofof thethe principalprincipal species'species' rotationrotation cycle,cycle, the forest manager must be able toto harvest secondarysecondary species logslogs marketable asas timber and/orand/ or constructionconstruction woodwood (posts,(posts, saw-wood).saw-wood) .

To optimizeoptimize thisthis harvest,harvest, thethe conformationconformation ofof thethe secondarysecondary speciesspecies stems must bebe satisfactory.satisfactory. From the silvicultural standpoint, cconformationonformation and planting densitydensity areare closelyclosely linked;linked; it is thusthus necessarynecessary toto adoptadopt aa planting densitydensity thatthat isis notnot prejudicialprejudicial toto thethe secondarysecondary species,species, whilewhile atat the same timetime interveningintervening vigorouslyvigorously onon thethe dominantdominant storey,storey, formedformed byby thethe principal species,species, whenwhen thethe firstfirst thinningsthinnings areare carriedcarried out.out. - 158 --

The following tabletable summarizessummarizes thethe recommendedrecommended densities:densities:

Planting 700 stems/ha 1 100 stems/ha 1 500 stems/ha densities

Mix: FramireFramiré + FrakéFrake Mahogany + Badi FramiréFramire + Teak Frake.Frak6 + Samba Mahogany + Niangon FrakéFrake. + Teak FramireFramiré + Samba Cedrela + Gmelina Samba + Teak OkouméOkoume + Mahogany Gmelina + Teak Gmelina + Samba Cedrela + Teak

The mix rate cancan bebe establishedestablished inin relationrelation toto thethe stand'sstand's vocation.vocation.

Stand vocation Mix rate

at planting at cycle end

Species 1 Principal + accompanying 40 -- 50%50%- 25 -- 35%35%- Species 22 50 - 60%60\ 65 -- 75%75\ Species 1 Single-tree 30 - 50%50\ 10 -- 50%50\ Species 22 50 - 70%70\ 50 -- 90%90\

The number of mainmain speciesspecies stemsstems planted shouldshould allowallow a selectionselection toto be effected within thisthis speciesspecies duringduring thinningthinning operations.operations.

6.4 - Recommendations

The management ofof mixed standsstands isis a delicate business that has not yet been thethe subjectsubject ofof detaileddetailed systematicsystematic experimentation.experimentation. However, the CTFT has forfor manymany yearsyears nownow beenbeen cultivatingcultivating behaviourbehaviour trialtrial plotsplots ofof mixedmixed species.

Analysis ofof thethe datadata cancan provideprovide silviculturalsilvicultural guidelinesguidelines forfor certaincertain mixes. However, thethe manager must clearlyclearly definedefine hishis objectivesobjectives beforebefore thethe stands are planted.planted . A stand'sstand's objectiveobjective conditionsconditions thethe silviculturalsilvicultural rulesrules that will be applied to it (planting(planting density, mix rate, thinning schedule and thinning rates, rotation,rotation, volumesvolumes harvested,harvested, ....). . )

The provisional silvicultural rules adopted for a principal species/accompanying species mix areare thosethose ofof thethe principalprincipal species.species. The accompanying speciesspecies mustmust inin factfact bebe treatedtreated soso thatthat itit does not compete with the trees of thethe principalprincipal species that are scheduled for full maturitymaturity (which(which gives rise toto thethe needneed forfor thinningthinning fromfrom aboveabove ofof thethe accompanyingaccompanying species,species, where trees are inin proximityproximity toto thethe dominantdominant partner).partner) .

For aa single-treesingle-tree mixturemixture thethe recommendedrecommended speciesspecies havehave compatiblecompatible silviculturalsi·lvicultural rules,rules, adjustableadjustable inin particularparticular inin relationrelation toto thethe proportionsproportions of thethe mixmix (the latter evolve in relationrelation toto thethe thinningsthinnings performed).performed). Silvicultural.Silvicultural actionaction thus makesmakes it possiblepossible toto favourfavour aa givengiven species,species, particularly when thethe secondsecond species'species' growthgrowth isis disappointing.disappointing. - 159 --

In CateCote d'Ivoire,d ' Ivoire, reafforestationreafforestation operations first beganbegan inin 1930 in moist evergreen forest.f,orest. On thethe basisbasis ofof thethe numerousnumerous applicationsapplications ofof thethe varvariousi ous enrichment andand reforestationreforestation methods implemented, it was possiblepossible to begin to gaingai n anan understandingunderstanding of thethe auto-ecology of certain moistmoist forest species. Numerous behaviourbehaviour trialstrials have made itit possible to define a rangerange of speciesspecies suitablesuitable forfor reforestationreforestation operations.operations. At the samesame time,time, thethe choice of reforestationreforestation methods andand species hashas evolved inin the light of acquired knowledge andand technicaltechnical andand economiceconomic imperatives.imperatives .

It must be realized that presentpresent reafforeafforestation.restation policypolicy isis subjectsubject toto strict economic imperativesimperatives thatthat havehave ledled toto · thethe selection:selection:

of speciesspecies thatthat areare easyeasy toto propagatepropagate andand thatthat showshow goodgood rootingrooting capacity whenwhen plantedplanted out;outj

of species thatthat grow with no cover and at a fast initial pace so as to limit thethe number of tendingtending operations necessary to ensure the successful growthgrowth ofof youngyoung plantations;plantations;

of species with high volume increments and consequently transplanting withwith aa medium-lengthmedium-length rotationrotation cycle.cycle. One of the aims is toto ensureensure staggeredstaggered short-termshort-term productionproduction thatthat cancan partiallyt?artially substitute forfor naturalnatural forest.forest.

For each homogenous ecological zone,zone, the selection of speciesspecies requiringrequiring no shade, with rootroot systemssystems able toto recover from possible injury during trans-trans­ planting, a fastfast growth-rategrowth-rate andand thethe abilityability toto growgrow inin mono-speciesmono-species standsstands is thus achieved by thethe useuse ofof behaviour-trialbehaviour-trial plots.plots.

After thesethese preliminaries,preliminaries, the silviculturalistsilviculturalist must resolveresolve the fofollowingl lowing problems forfor eacheach speciesspecies selectedselected asas suitablesuitable forfor reforestationreforestation use:

identification ofof the provenances suited to each reforestationreforestation zone;

definition of the types of transplantstransplants required and their productionproduction techniquesjtechniques;

identification of the minimum densities necessary to obtain well-shaped trees,trees,

adventitious vegetationvegetation controlcontrol operationoperation schedulesschedules andand methods;methods;

whether or notnot artificialartificial pruningpruning isis necessarynecessary toto improveimprove thethe quality ofof thethe wood;wood;

definition of thethe thinningthinning regime,regime, adjusted inin relationrelation toto sitesite fertility;

the influence of exploitable diameter on the rotation cycle andand the nature ofof thethe logginglogging products.products.

Of course thisthis document isis onlyonly aa very incomplete memorandum forfor thosethose in charge of timbertimber-oriented- oriented reforestation oprations, and for sisilviculturalistsl viculturalists inin particular. The CTFT results are presented as concisely as possible fromfrom thethe standpoint of transferring the researchresearc h findings to the development phase.phase. - 160 --

In certain cases, in particular as regards the silvicultural rules for species such as Gmelina,Gmelina, BadiBadi andand Pine,Pine, somesome recommendationsrecommendations areare onlyonly ofof aa provisional character asas theythey are based on trials of a fragmentary naturenature oror that are stillstill inin progress.progress.

It isis consideredconsidered thatthat silviculturalsilvicultural researchresearch effortsefforts onon timber-orientedtimber-oriented plantations shouldshould bebe pursuedpursued inin thethe followingfollowing directions:directions:

continuation ofof efforts toto identifyidentify newnew fast-growing,fast-growing I coverlesscoverless timber species;species j

improvement of tending, pruning, etc. operations for young stands;stands ;

establishment ofof growthgrowth modelsmodels for the various species used for industrial reforestationreforestation purposes.purposes. These growth models must allow adjustment of the average interventionintervention rules in relationrelation to sitesite conditions or particular standstand characteristics.characteristics.

the establishment or pursuit of supplementary silvicultural programmes forfor thosethose speciesspecies whosewhose silviculturalsilvicultural rulesrules areare stillstill only provisional.

study of the aassociationssociation of certain species in mixedmixed plantationsplantations and the silvicultural rulesrules forfor thethe standsstands thusthus established.established.

Such a programme, with itsits long-term span, could only be implemented in close collaborationcol labora~ion with thethe usersusers ofof researchresearch findings.findings. AsAs regardsregards thethe silvicultural rulesrules establishedestablished byby thethe research programme, itit is probable that they will sometimes havehave toto bebe adaptd toto specialspecial cases,cases, inin thethe lightlight of which it willwill bebe possiblepossible tot o achieveachieve aa betterbetter understandingunderstanding ofof the reality.reality. Development-research feedback willwill thus be welcomedwelcomed for its potential contribution to those production models which have to cover a wide range of opoptions.tions .

The followingfollowing recommendationsrecommendations concern the choicechoice ofof reforestationreforestation species:

Zone Pure standsstands Mixed stands

Long Medium cyclecycle cyclecycle Long cycyclecle Medium cyclecycle

Moist evergreeen Niangon FramireFramiré Mahogany ++ NiangonNiangon forestfore st OkoumeOkoumé Gmelina Mahogany + BadiBadi Badi PinePiness

Moist Semi-deciduous Teak FramiréFramire FramiréFramire ++ Frake" Frake forest Badi FrakéFrake Samba + FrakéFrake Samba FramiréFramire + TeakTeak CedrelaCedreJa Samba + TeakTeak Gmelina Gmelina + TeakTeak Pines FralccFraké + TeakTeak

PrePre-forest-forest Teak Gmelina Gmelina + TeakTeak - 161 --

It iiss obvious thatthat the proposed silvicultural rules invite manymany comments. In particular, as regards the planting densities, two groups ofof species can be distinguished:

Species for which thethe standstand effect is indispensable toto goodgood stem

conformation (especially(especially straightness),straightness) I such as Teak,Teak, CedrelaCedrela oror Gmelina. Good-quality stands require compliance withwith the minimum density thresholds,threshol ds, especiallyespecially atat plantingplanting time.time.

Speciesspecies whose shapeshape isis notnot greatlygreatly affectedaffected by density,density, such asas Terminalia. For these species it is possible to opt forfor widely

spaced plantingplanting ( 5 x x 55 m, i.e.i . e. 400 stems/ha).stems/hal. This solutionsolution entails a dynamicdynamic silviculturalsilvicultural approach, includingincluding in particular pruning toto avoidavoid thethe presencepresence ofof largelarge knotsknots inin thethe wood.wood. These low planting densities also make itit possiblepossible toto eliminateeliminate thethe firstfirst thinning, whichwhich isis alwaysal ways expensive.expensive. WithWi th thethe useuse ofof improvedimproved planting stockstock it maymay bebe possiblepossible to further reducereduce plantingplanting density.

Such widelywidely spacedspaced planting may also suggestsuggest thethe possibilitypossibility ofof temporary associationsassociations with interplantedinterplanted foodfood cropscrops (maize and groundnuts inin particular)particular) untiluntil thethe canopycanopy beginsbegins toto close.close. Such interplantedinterplan~ed cropscrops areare alsoalso aa useful way of facilitating the control of undesirable adventitiousadventitious vegetation and enhancingenhancing thet he stands'stands 1 profitabilityprofitability.. These annual crop associations, effectedeffected duringduring thethe initial years of thethe stand'sstand 1 s lifetime,lifetime, would make itit possiblepossible toto reduce the number of tendingtending operations and assure an annual food harvest. But these considerations are already bringing us toto thethe borderland withwith agro-forestry.agro-forestry.

It isis notnot ourour intentionintention herehere toto drawdraw up anan exhaustiveexhaustive list of thethe research toto bebe undertaken.undertaken. Dynamic reforesteation should encourage us toto channel our energies towards activities that can produce quick results, andand yet not make us lose sightsight of thethe factfact that forestry will always be a long-long­ term business.

We also feel itit isis importantimportant toto draw attention yet againagain toto thethe bodybody of experience available on plantationplantation silviculture in lowland moist forest zones. Nevertheless, recourserecourse toto industrialindustrial plantationsplantations mustmust notnot mask the need to prevent thethe impoverishmentimpoverishment andand excessiveexcessive degradationdegradation ofof naturalnatural forest.forest . Their management couldcould decreasedecrease thethe necessitynecessity forfor the labour-intensive silvicultural techniquestechniques andand alterationsalterations inin thethe naturalnatural environmentenvironment inherentinherent in commercialcommercial reforestation. This process isis in fact not without its hazards, especially from thethe phytopathologicalphytopathological standpoint.standpoint.

Experience also showsshows that it is necessary toto control in the vicinity of forest stands, and wouldwould suggsuggestest the desirability of combining, whenever possible,possible, thethe management ofo f natural stands with reforestation. The latter solution would bebe reservedreserved for degradeddegraded stands which must bebe convertedconverted intointo even-agedeven-aged plantations.plantations. - 162 -

7 - PLANTATIONS OF FIFTY-EIGHT LESSER-KNOWN SPECIES NATIVENATIVE TOTO AFRICANAFRICAN MOISTMOIST FORESTS

Fifty-eight speciesspecies nativenative toto thethe African closed forest zonezone have been planted with nono sheltershelter onon trialtrial plotsplots onon variousvarious sitessites withwith climaticclimatic conditions corresponding to moist evergreen forest, transitional evergreenevergreen/semi-deciduous/ semi - deciduous forestforest andand semi-deciduoussemi-deciduous forest.forest.

The trial plots were established from 1981 onwards on the following sites in C6teCote d'Ivoire:d'Ivoire:

Yapo, inin moist evergreenevergreen forest,forest,

Mopri, inin transitionaltransitional semi-deciduous/evergreensemi-deciduous/ evergreen forest,forest,

Sangoué,Sangoue, inin semi-deciduoussemi-deciduous forest.forest .

In the research zone in question,question, the meanmean annualannual rainfallrainfall ranges from 1 200 mm/yearmm/ year toto 11 800800 mm/year.mm / year. The duration of the dry season isis between 33 and 6 months.

The information contributed by thesethese trials is of the greatestgreatest importance. They prove quite simplysimply thatthat manymany naturalnatural forestforest speciesspecies cancan bebe successfully plantedplanted withwith nono cover.cover.

Their initial growth isis satisfactory: thethe mean height incrementincrement oftenoften eexceedsxceeds 1 m/year.m / yea~ . The chief silvicultural parameter requiring attention is the need for painstaking and repeated tending untiluntil thethe treestrees areare free ofof regrowth.

Due to their ecological characteristics,characteristics , somesome speciesspecies werewere introducedintroduced on several sites.sites. The planting sitesite totallytotally cleared,cleared, eitherei.ther manuallymanually (Yapo)(Yapo) oorr mechanicallmechanicallyy (Mopri(Mopri andand Sangoué).Sangoue) . The treestrees were planted on open ground at intervals ofof 33 mm xx 3 3 m.m. - 163 -

LIST OF SPECIES TESTED ON BEHAVIOUR-TRIAL PLOTS ON THE THREE SITES (YAPO,(YAPO, MOPRIMOPRI ANDAND SANGOUE)SANGOUE)

Species Scientific names

1 Abale Petersianthus rnacrocarpamacrocarpa 2 Aboudikro EntrandrophragmaEntrandrophragrna cylindricurncylindricum 3 Bassam mahogany KhayaIChaya ivorensis 4 White mahogany Khaya anthothecaan tho theca 5 Broad-leaved mahogany Khaya grandifolia 6 SenegaSenegall mahogany Khaya senegalensis 7 Adjouaba Dacryodes klaineana 8 Ai616Ai,He Canarium schweinfurthii 9 Akatio ChrysophyllumChrysophyllurn africanumafricanurn 10 Ako Antiaris africana 11 Akoua Antrocaryon africana 12 Amazakou6Amazakoue ehie 13 White aniegreaniégré Aningeria robusta 14 Aribanda Trichilia lanata 15 Azob6Azobe Lophira alaalata ta 16 Azodau Afzelia bella v. gracilior 17 Ba Celtis mildbraedii 18 Badi Nauclea diderichii 19 BaheDalle" Fagara macrophylla 20 BeteBét6 Mansonia altissima 21 Bi Eribroma oblonga 22 Bodo Detarium senegalense 23 BonDon Cordia PlatythyrsaPlaty thyrsa 24 BosseBoss6 GuarGuareaea cedratacedra ta 25 Dabema Piptadeniastrum africanum 26 DibetouDibétou Lovoa trichiliodes 27 Difou Morus rnesozigiamesozigia 28 Eho Ricinodendron africanum 29 Emien Alstonia boonoiboonoi 30 EtimoeEtimoé Copaifera salikounda 31 Faro Daniellia ogea 32 Silk-cotton tree Ceiba pentandra 33 Iatandza Albizia ferrugineaferruginea 34 IlombaTimba Pycnanthus angolensis 35 Iroko Chlorophora excelsa 36 Ko melega Berlinia confusa 37 Kosipo EntandrophragrnaEntandrophragma condolleicondollei 38 KotibeKotibé Nesogordonia papaverifica 39 Koto Pterygota macrocarpa 40 Lati AmphimasAmphirnas pterocarpoides 41 LingueLingu6 Afzelia africanaafricana 42 Lo Parkia bicolor 43 LohonfeLohonf6 Celtis adolphi federicifederici 44 Lotofa Sterculia rhinopetala 45 MakoréMakore Thieghemella heckelii 46 Melegba Berlinia grandifgrandiflora lora 47 Movingui DisternonanthusDistemonanthus benthamianusbentharnianus 48 Niangon Heritiera utilis 49 Oba Bombax buonopozense 50 Ouara Cola gigantea 51 Ouochi Albizia zygiazygia 52 Poré-poréPore-pore Sterculia tragacanthatragacantha 53 Pouo Funtumia africana 54 Rikio Uapaca guineensis 55 Sipo Entandrophragma utile 56 SougueSougué Parinari excelsaexcelsa 57 Tali Erythrophleum ivorense 58 Tiama EntandrophragmaEntandrophragrna angolense -- 164 --

7.1 - Major results after tenten yearsyears

Moist evergreenevergreen forestforest

The mean annualannual rainfallrai nfall exceeds 1 600 mm/year, the length ofof the drydry season averages lessless thanthan 44 months andand thethe mean annualannual waterwater deficitdeficit isis lessless than 300 mm/year.

Oba,Dba, Badi,Badi , Niangon, Ni angon, Aribanda, Bon, Pouo,Pouo , Makor6Makore and Tali show a mean height increment ofof over 1.51.S m/yearm/year,, and their memeanan diameterdiameter incrementincrement exceeds 1.5 em/year.cm/year.

All thesethese speciesspecies havehave aa goodgood survivalsurvival rate.rate.

Attention isis alsoalso drawndrawn toto thethe goodgood behaviourbehaviour ofof BassamBassam mahogany,mahogany, Lingue,Lingué, Kato,Koto, Akoua andand Ouochi.Ouochi.

Transitional evergreen/semi-deciduousevergreen/ semi - deciduous forestforest

The mean annual rainfallrainfall isis betweenbetween 11 300300 mm/yearmm/ year andand 11 600600 mm/year.mm/ year . TheThe dry season averages from 3 to 55 months.months . As a generalgeneral rule, the mean height increment isis lessless thanthan 1.51.5 m/year.m/ year.

The species which have mean diameter increment exceeding 2 cm/year and a goodgood survivalsurvival rate are: Badi, Silk-cotton tree, Oba, OuOuochi,o chi, and Pore-pore.Poré-poré.

Lingue,Lingué, Koto andand BétéBete alsoalso behavebehave satisfactorilysatisfactorily underunder plantationplantation conditions.

SemiSemi-deciduous deciduous forestforest

The mean annual rainfallrainfall rangesranges fromfrom 11 000000 mm/yearmm/ year tot o 11 400400 mm/year.mm/ year. The duration ofof thethe drydry seasonseason isis 44 to 6 monthsmonths.. TheThe meanmean annualannual waterwater defideficitcit is less than 700700 mm/year.mm / year.

Only 26 percent of thethe testedtested species showed a mean height increment exceeding 11 m/year.m/year .

The species thatthat combinecombine aa good survivalsurvival raterate with sufficientsufficient initialinitial growth areare:: Badi,Badi , Oba, PorePoré-poré,- pore, Ouara, White Mahogany, Broad-leaved Mahogany, SenegalSenegal Mahogany,Mahogany, Lingué,Lingue, KotoKoto and and Bete'. Bete.

7.27 . 2 - Findings and recommendations

The best growth ratesrates areare recordedrecorded inin thethe moistmoist evergreenevergreen forestforest zone.zone. The initial height increment is about 1 mm/year/ year up to thethe ageage of 5 years.years. After this settlingsettling-in- in phase, the mean height increment stabilizes atat aroundaround 1.5 mm/year./ year.

In the semi-deciduous forest, the initial growth recorded is generallygenerally lower. At thethe ageage ofof 1010 yearsyears itit isis ofof thethe orderorder ofof 11 m/year. m/ year. - 165 -

LIST OF SPECIESSPECIES WITHWITH AA SURVIVALSURVIVAL RATERATE EXCEEDINGEXCEEDING 7596 75% AND AA MEANMEAN DIAMETERDIAMETER INCREMENTINCREMENT OFOF OVEROVER 1.51.5 CM/YEARCM/YEAR

NATURAL STAND

Evergreen Transitional Semi-deciduousSemi -deciduous forest forest forest

Oba Silk-cotton tree Oba Akoua Oba Pore-porePoré-poré Melegba Pore-porePor6-por6 White Mahogany Badi Badi Br. 1.l. Mahogany MakoréMakore Bon Sen. Mahogany PouoPouo Emien Quochi Koto LingueLingué NiangonNiangon Kato Bon Tali

The technologicaltechnological qualityquality ofof the wood isis oneone ofof thethe fundamentalfundamental criteria forfor thethe choice of a reforestationreforestation species. Taking this parameter intointo consideration, the species thatthat showshow goodgood plantationplantation behaviourbehaviour (survival,(survival, growth, shape)shape) andand areare toto be given priority for reforestation purposes areare thethe . following:

SPECIES TO BE PROMOTEDPROMOTED FORFOR REFORESTATIONREFORESTATION PURPOSESPURPOSES

Evergreen forest:forest: Oba, Makore,Makor6, Bassam Mahogany, Niangon, Badi,Badi, Pouo, Koto,Keto, Lingu6Lingue

Semi-deciduous forest:forest: Silk-cotton tree, Oba, Badi, Koto,Kato, White Mahogany, Broad-leaved Mahogany, SenegalSenegal Mahogany, Lingué,Lingue , Bété.Bete .

Some of thesethese speciesspecies (Mahogany,(Mahogany, Niangon,Niangon, Sipo,Sipo, Makoré,Makore, Badi,Badi, etc.) have already been used inin thethe past for rereforestationforestation purposes. The successful use of thesethese speciesspecies isis basedbased onon thethe strictstrict controlcontrol ofof tendingtending operationsoperations during the earlyearly years and onon thethe adoptionadoption of high planting densities that ensure thethe quickquick closureclosure ofof thethe canopy.canopy.

For speciesspecies withwith relativelyrelatively slowslow initialinitial growthgrowth (S(Sipo,ipo, NiNiangon,angon, Makore), widely-spaced planting has seldomseldom provedproved successful,successful, takingtaking intointo account thethe natural mortalitymortality oror thatthat duedue toto insufficientinsufficient tending.tending. This type of plantingplanting involvedinvolved retainingretaining a portionportion ofof thethe pre-existingpre-existing covercover (strip(strip planting method,method , undergrowthundergrowth method,method, ...... ). ). - 166 -

GROWTH RESULTS OF THE SPECIES TESTED ON THE THREE EXPERIMENTAL SITES

Species YapoYapo site Mopri site SangoueSangoué site Age AlAlive ive C HN Age AlAlive ive C HN Age AlAlive lve C HN (yrs)(yrs) X% (

AbaleAbate 8 0 10 0 Aboudikro 7 74 32.2 5.4 Bassam mahogany 8 76 45.5 12.1 WhWhite i te mahogany 8 98 28.1 6.2 10 100 56.2 11.9 Br.Br.-1. -1. mahogany 8 96 36.8 8.8 10 98 52.7 13.3 Sen. mahogany 10 98 52.3 9.2 Adjouaba 7 55 16.2 22.1. 1 AieleAiélé 7 47 37.637.6 10.1 8 65 34.3 9.0 Akatio 10 0 10 0 Ako 66 61 32.5 4.7 10 18 55.9 11.0 10 12 26.7 5.3 Akoua 7 94 49.8 8.6 AmazakoueAmazakoué 8 78 30.3 6.9 10 0 ~iteWhite aniegreaniégré 8 12 28.4 4.8 10 0 Aribanda 8 59 57.2 1313.7.7 10 4 43.0 99.4.4 10 29 40.2 8.3 Azobe 8 98 31 11.7 10 31 35.1 10.010.0 Azodau 8 80 25.9 77.2.2 10 33 40.5 8.1 10 29 34.4 6.9 B.Ba 10 43 39.1 8.9 9 96 15.7 2.4 BacHBadi 10 59 66.2 15.0 10 61 74.4 13.213.2 BaheBahé 7 90 2424.8.8 7.0 8 37 51.8 Bete 6 96 34.2 77.4.4 10 96 38.9 9.9 10 86 28.0 5.2 Bi 8 96 36 10 33 4343.3.3 11.4 10 2 21.0 3.7 Bodo 6 73 2.3 Bon 6 100 54.1 10.010.0 8 92 39.4 9.5 Bosse 7 39 13.3 2.52. 5 0 0 10 0 OabemaDabema 8 49 35.6 8.1 DH:,etouDibétou 8 0 10 0 Difou 6 94 28.9 5.6 8 57 25.2 9 8 21.3 4.4 Eho 8 33 50.4 9.4 10 14 100.1 14.8 10 4 90.590 .5 11.011.0 Emien 6 98 46.7 7.0 8 90 58.0 10.510 .5 EtimoeEtimoé 6 100 15.1 3.4 8 80 20.320.3 4.1 Faro 4 51 16.5 2.5 8 63 27.6 10 31 17.5 4.4 Silk-c. tree 10 88 92.0 14.1 tatendz8latandza 9 8 32.0 6.0 Ilomba 6 29 39 4.7 10 0 lrokoIroko 8 86 34.8 6.9 10 0 10 0 I(osipoKosipo 7 84 28.6 5.5 Kotibe 5 94 21.7 4.4 10 16 50.7 4.2 10 16 28.4 4.7 Koto 8 82 39.7 10.0 10 80 53.3 14.2 10 94 37.3 6.7 Latilat; 8 6 6 39.0 Linguélingue 8 100 40.440 .4 11.6 10 100 36.3 11.0 10 82 38.6 7.8 Lo 7 98 23.823 .8 5.1 8 41 48.0 9 33 32.3 5.9 LohonféLohonfe 8 37 37.8 3.9 10 0 10 4 52.552 .5 11.511.5 LotofaLatah 8 45 18.3 3.13. 1 10 67 31.9 5.3 10 49 28.7 4.9 MskareMakore 7 96 43.1 10,9109 8 2727 31.3 Melegba 7 76 45.5 6.5 10 43 42.8 7.1 Movingui 5 71 21.9 6.3 Niangon 8 90 40.1 1414.4.4 8 8 43.3 DbaOba 8 51 83.8 4.2 10 43 109.1 1212.2.2 10 80 74.1 10.6 Ouara 10 57 53.5 7.4 OuochiOUochi 7 80 40.1 8.4 8 43 57.5 9 20 35.3 6.26.2 Pord-poréPore-pore 10 92 63.0 12.2 10 80 58.458.4 10.110.1 Pouo 8 90 47.5 12.5 8 49 46.746.7 RikioIUkio 8 51 59.5 12.3 Sipo 6 88 31.1 7.2 8 20 45.345.3 10 2 11.0 2.42.4 SouguéSougue 5 86 36.5 9.4 Tali 5 96 33.9 12.0 TiernaTiama 8 69 25.4 5.7 10 0 10 2 48.048.0 15.515.5 - 167 -

The results now available, tenten years after planting, clearlyclearly showshow that:that:

most speciesspecies areare perfectlyperfectly ableable toto toleratetolerate plantingplanting inin fullfull lightlight

the chief constraintconstraint onon thethe successfulsuccessful plantingplanting ofo f timbertimber speciesspecies is the need forfor carefulcareful and repeated tending over a periperiodo d of 5 to 1020 years.years .

One of the successfully testedtested solutionssolutions forfor controlling adventitious vegetation isis thethe useuse ofof soil-coveringsoil-covering plantsplants suchsuch asas PuerariaPueraria oror Leucenea.Leucenea. This technique does notnot decreasedecrease thethe numbernumber ofof tendingtending operationsoperations butbut allowsallows effective control ofof weedsweeds whilstwhilst assuringassuring excellentexcellent soilsoil protection.protection.

The silviculture ofof long-rotationlong-rotation timbertimber treestrees isis veryvery demandingdemanding atat thethe time of planting andand duringduring thethe standsstands' initial establishment.establishment. The basicbasic silvicultural recommendationsrecommendations forfor successfulsuccessful plantingplanting areare thethe following:following:

good-quality plantingplanting stock,stock,

40 x 4040 xx 4040 cmcm plantingplanting pits,pits ,

application ofof starterstarter fertilizer,fertilizer,

maximum spacingspacing 3 m x x 33 m,m,

pre-emergency weedkillerweedkiller treatment,treatment,

the use of aa soil-coveringsoil-c overing plantplant (Pueraria,(Pueraria, LeuceneaLeuc enea ...),... ),

constant tendingtending untiluntil thethe firstfirst thinnings.thinnings.

In manymany cases, the studistudiese s regarding the optimumoptimum thinning scheduleschedule are not yet finalizedfinalized oror havehave notnot yetyet begun,begun, butbut thethe silviculturalsilvicultural datadata acquiredacquired is considerablconsiderablee and awaits fullfull exploitation.exploitation. - 168 -

CHAPTER 44

EVOLUTIONARY TRENDSTRENDS ANDAND NEEDSNEEDS

During thethe pastpast severalseveral decades,decades, foresters have concentratedconcentrated theirtheir studies on thethe problemsproblems regardingregarding transplanttransplant production,production, competition and productivity.productivity . Their resultsresults provide ample proof of the seriousness of their research efforts.efforts.

These research endeavours must be continued in a number of different directions:

The study ofof newnew species;species; The soil/growth relationship;relationship; Production models;models; The study ofof mixturemixture stands;stands; The silviculture/breeding/technology relationships; Plantation management.management.

11 - ·'I1HETHE STUDY OF NEW SPECIES

The increasing scarcityscarcity ofof woodwood fromfrom natural forests has led to trials of numerous species transplanted toto open terrain (BERTAULT(BERTAULT 1982, DUPUY 1990)1990). .

Promisingpj;;o.mising speciesspecies are:are: thethe KapokKapok treetree (Ceiba(Ceiba pentandra)pentandra),, the Oba tree

(Bomb-ax(Bombax buonopense),buonopense) I the Bete'Bete tree (Mansonia altissina),al tissina), the PuouPuou treetree (Funtumia elastica), the Rikio treetree (Uapaca(Uapaca guinéensis),guineensis) , etc.etc.

For each ooff thethe afore-mentionedafore-mentioned species, the traditional approach would be: transplanttransplant production,production, competitioncompetition trialstrials andand productivityproductivity studies.studies.

2 - TIl~THE .. ,SOIL/GROWTHSOIL/GROWTIl RELATIONSIlIPRELATIONSHIP

This site study component isis indispensableindispensable ifif we are to improve on the relationship between thethe reforestationreforestation sitesite andand thethe speciesspecies planted.planted.

The purpose ofof thethe soil/growthsoil/growth relationshiprelationship study is toto allowallow us toto evaluate the influenceinfluence thatthat thisthis parameterparameter mightmight havehave onon reforestationreforestation productivity. PhysicalPhysical (texture,(texture, structure,structure, depth,depth, ...... ) ) asas wellwell as chemical (pH, chemical reserves,reserves, deficiencies, ...... ) ) and hydrichydric soilsoil studiesstudies areare required. In thisthis regard,regard, the dynamicdynamic aspect of thethe waterwater elementelement isis a fundamental one inin tropicaltropical zones, inasmuch as it is the principal limiting factor here.here .

With respect toto stand development, we alsoalso need studiesstudies on:on :

fertilization toto correctcorrect deficiencies;deficienciesi drainage for the reforestation of hydromorphic and low-lying areaSiareas; working the soil andand herbicidesherbicides activeactive inin thethe hydrichydric balancebalance ofof young plantations. - 169 --

3 - PRODUCTION MODELS

Once thethe firstfirst generationgeneration ofof yieldyield tablestables is completed,completed, research efforts must bebe continuedcontinued toto developdevelop moremore effectiveeffective productionproduction models.models.

These should integrate silvicultures adaptable to differentdifferent productionproduction models. The financial aspects areare taken into considerationconsideration after the technicaltechnical aspects toto helphelp inin decision-making.decision-making.

4 - STUDIES OF MIXED STANDS

This isis one aspect ofof silviculturalsilvicultural techniquestechniques thatthat mustmust bebe developeddeveloped here. There are manymany reasons forfor associatingassociating aa number of different speciesspecies inin the planting process:process:

to limitlimit impactimpact ofof plantplant protectionprotection problemsproblems inin singlesingle speciesspecies plantations;

in orderorder toto facilitatefacilitate weedweed control,control, andand limitlimit forestforest firesfires byby multi-story stands;stands;

to reduce the extent of tthehe firstfirst earlyearly thinningthinning byby reducingreducing densitydensity and therebythereby thethe onsetonset ofof competitioncompetition inin thethe overstorey;overstoreYi

ttoo develop species combcombinationsinations which maintain and improve fertility.

Two priority courses of actionacti on should be explored.explored. The firstfirst would ininvolvevolve the creation of two-storey standsstands ofof thethe coppice-with-standards type,type, by associating aa dominantdominant timbertimber speciesspecies withwith aa dominateddominated fuelwoodfuelwood speciesspecies such as Fraké,Frake, Framir6Framire oror SambaSamba ...... withwith Teak.Teak.

The second course of action would bebe toto associate timbertimber speciesspecies withwith

Acacias (such as mangium,mangium l auriculifacmis,auriculiformis l ...)• • • ) that cancan enrichenrich thethe soil,soil, particularly withwith nitrogen.nitrogen.

And finally,finally, thethe plantingplanting ofof speciesspecies thatthat growgrow inin thethe shadeshade underunder aa cover or canopy ofof Leucaena remainsremains aa techniquetechnique toto bebe exploredexplored andand promoted:promoted: the first resultsresults ofof suchsuch plantingsplantings havehave beenbeen encouraging.encouraging.

5 - RELATIONSHIPS BETWEEN GENETIC IMPROVEMENT,IMPROVEMENT, SILVICULTURESILVICULTURE AND TECHNOLOGYTECHNOLOGY

Research inin genetic improvement,improvement, aa stepstep that precedes silviculture,sil vicul ture, hashas made possible aa higherhigher qualityquality plantplant material.material . GeneticGenetic researchresearch findingsfindings should allow us toto reducereduce density,density, andand inin certaincertain cases,cases, toto advanceadvance towardtoward very widewide spacingspacing (Terminalia{Terminalia spp.spp. Samba, ... ) This kind of silviculturesilviculture should be testedtested andand evaluated.evaluated.

TheThe search for quality wood alsoalso leadsleads toto the development ofof artificial pruning.

The impact of thinning systems and planting density on the characteristics of woods shouldshould bebe quantifiedquantified byby woodwood technologytechnology studies.studies . - 170170 --

6 - PLANTATION MANAGEMENT

Plantations areare aa tooltool forfor thethe regenerationregeneration ofof ourour forestforest heritage.heritage.

Their high cost justifies the considerable amount of research that has been carried out during the past decades, inin order to optimize their creation and management. The perpetuation of a natural or manmade forest depends, at the present time, onon forestforest management.management.

Overexploited natural forests must be partially regenerated by plantations particulary inin sufficientlysufficiently fertilefertile degradeddegraded zones.zones.

The development of yield tables for the principalprincipal reforestation speciesspecies constitutes a decisive stepstep in plantationplantation management.management. Such tables,tables, in particular, allow forestry operations to be tailored to site fertility, and future yields toto bebe evaluated.evaluated.

The optimization of managementmana gement planningplanning andand interventionsinterventions areare thethe twotwo factors that guarantee rationalrational plantationplantation management.management.

At the presentpresent time,time, reforestationreforestation is an integralintegral part of tropicaltropical forest management. ThrThrougho ugh the selection of quickquick-growth- growth species, staggered production to regenerateregener.ate natural formations that are far tootoo oftenoften over-over­ exploited becomes possible.possible.

Reforestation, whichwhich isis inseparableinseparable fromfrom natural forestforest silviculture, is relevant where a sitesite isis unquestionablyunquestionably suitablesuitable forfor forestry.forestry.

It thenthen permitspermits the conconversionversion of part of the heavily degraded naturalnatural stands into productiveproductive even-agedeven-aged plantings.plantings.

The principal problem today is the financial evaluation of reforestation ooperationsperatio ns that are far mmoreo re costly than the extensive managementmanagement of naturalnatural formations.formations .

The right answer depends, inin particular, onon models thatthat integrateinte.grate thethe technical and financial aspectsaspects of thethe problem.problem. Inasmuch as thethe final objective of intensive reforestation is the harvesting of wood, the technological and development ccomponentomponent will strongly condition the flexibility of thethe model.model.

computerComputer software forfor forestf o rest managementmanagement mustmust thereforetherefo re bebe developed.developed. Even-aged plantations areare oobviouslybviously an idealideal researchresearch frameworkframework for suchsuch activities.

A forest tends to be cconsideredo nsidered as an enterprise inin which an investment should result inin a long-rangelong-range profit.profit. OnOn thethe otherother hand,hand, however,however, itit shouldshould also produce regular income to cover current annual expenses, as well as minimizeminimize the amount of working capital tiedtied upup byby thesethese expenses.expenses.

This objective can only be achieved if each of the stands is managed independently from allall of the others.others. One mustmust therefore proceedproceed from silvicultural management to iintegratedntegrated forestf o rest managementmanagement by programmingprogramming volumevolume and income distribution.

InIn thethe long run, expertexpert systemssystems ooff fforesto rest managementmanagement (administrative, technical and fiscal management)management ) must be thethe ultimateultimate goal.g o al. SuchSuch aa system s y stem would,would, in particular: - 171 --

define thethe groundground rulesrules governinggoverning operationsoperations needed toto createcreate plantations;

define the forestryforestry operations neededneeded toto obtainobtain aa level of wood production thatthat meetsmeets thethe forestryforestry objectives;objectives;

adapt harvest programmingprogramming toto thethe medium-termmedium-term economiceconomic conditions.conditions.

CONCLUSCONCLUSION ION

When tropical forests first began to bebe exploited,exploited, logginglogging concentratedconcentrated on aa fewfew species.species. Foresters,Foresters I concernedconcerned thatthat thisthis typetype of forestforest mightmight bebe impoverished, turned their attention toward enrichment plantations to compensate forfor thethe woodwood removedremoved byby logging.logging.

As timetime wentwent on,on, thethe numbernumber ofof commercialcommercial speciesspecies increasedincreased tenfoldtenfold within a fewfew decades.decades. ApproximatelyApproximately one hundredhundred tropicaltropical forest species are now of commercialcommercial interest.interest.

In fact, the forestforest was still very "rich""rich" at the time of thethe firstfirst enrichment andand planting trials,trials, as successive exploitation shows. The .interest in enrichment forestsforests waswas duedue toto aa material constraint,constraint, namely,namely, thethe materialmaterial lack ofof clearingclearing facilities,facilities, as wellwell asas thethe desiredesire toto avoid,avoid, insofar asas possible, modifyingmodifying thethe ecosystem.ecosystem.

Manual methods cancan bring about excellent results, if theythey areare correctlycorrectly applied. Unfortunately, however,however, socio-economicsocia-economic andand technical constraints have put an endend toto suchsuch methods,methods, inin favourfavour ofof moremore intensiveintensive operationaloperational methods.methods .

Intensive methods were justified by the increasing impoverishment of the natural forests, as well as byby aa formform ofof competitioncompetition between forestryforestry andand agriculture, andand by technological progress.progress. Furthermore,Furthermore, notnot enoughenough waswas known about thethe silviculturesil vicul ture ofof naturalnatural standsstands toto convinceconvince decision-makersdecision-makers toto implement thesethese methods.methods.

After severalseveral decadesdecades ofof research, wewe are now confidentconfident that wewe possesspossess the knowledge necessary forfor reforestation inin humidhumid tropicaltropical zones.zones. At the same time, we have been able to developdevelop silviculture operationsoperations inin naturalnatural forests.forests . As aa consequence,consequence, forest managers today have at theirtheir disposaldisposal allall thethe technical toolstools theythey needneed toto conserve natural forests,forests, oror to convert them into even-aged plantations. AllAll theythey needneed thenthen dodo isis choosechoose thethe technicaltechnical optionsoptions they wish toto use inin termsterms ofof existingexisting constraintsconstraints andand theirtheir ultimateultimate goals.goals.

CHOOSING THE BEST TECHNIQUE

The first concern of the forest manager isis to make an inventory of and map the stands, inin accordance withwith aa typologytypology adaptedadapted toto thethe goalsgoals ofof forestforest management.

This should bebe establishedestablished in terms of the availableavailable range ofof silvicultural techniques.techniques.

The parameters forfor considerationconsideration are,are, inin particular:particular:

Cover, or continuouscontinuous canopycanopy (photo-interpretation);(photo-interpretation); - 172 --

The abundance of commercial species (statistical(statistical inventory);inventory);

The site potential (topography,(topography, fertility,fertility, vulnerability,vulnerability, etc.);etc.);

The human and agricultural pressurepressure (intensity,(intensity, typetype ofof crop).crop).

This should make itit possiblepossible toto map thethe forestforest areaarea andand toto plotplot thethe homogeneous units whichwhich wouldwould justifyjustify aa uniformuniform silviculturalsilvicultural treatment.treatment.

The size of these plots depends on the meansmeans available; one plot would normally consist of several dozen hectares. Indicatively, minimum plot size should be inin thethe orderorder of:of:

10 hectares forfor manual reforestationreforestation techniques;techniques;

30 hectares for mechanized reforestation techniques;

50 hectares forf or enrichment techniques in natural forests.forests.

Plot size should take intc accountaccount technicaltechnical andand economiceconomic requirements. This operational basisbasis might possiblypossibly undergo somesome changes asas further studies are made.made.

Grouping thesethese landland unitsunits toto seriesseries ofof operations suchsuch asas protection,protection, production or regeneration should make it possible to schedule the silvicultural operations to coincide with the implementationimplementation of managementmanagement plans.

The chronological sequencesequence of thethe managementmanagement operationsoperations shouldshould taketake into account the technical limitslimits imposedimpo sed by the implementationimplementation of aa givengiven technique:

Per Hectare Costs of thethe DifferentDifferent SilviculturalSilvicultural TechniquesTechniques

Technique Labour Cost Equipment CostCost Estimated Cost MD/haMD /ha M/ha 1989 FCFA/ha

Improvement 15 0.5 50 000 Natural Stand

Enrichment 60 1 150 000

Manual Conversion 120 1 300 000

Mechanized Conversion 50 15 800 000000

The principal limitinglimiting factor,factor, inin reality, isis the cost of implementing each of thesethese techniques,techniques, beginning withwith the first year. The costs to be incurred later on refer to maintenancemaintenance (cleaning, clearing, delianage),délianage), or to development operationsoperations (trimming,(trimming, pruning,pruning, thinning)thinning) ofof thethe existingexisting stands.stands. - 173 --

Relative Requirements: LabourLabour Equipment/perEquipment/per HectareHectare duringduring thethe FirstFirst YearYear

Technique Labour costcost Equipment costcost % per hectarehectare MD/ha M/ha

Improvement 50% Natural StandStand 7 0.4 80%

50% Enrichment 30 0.4 80%

Manual Conversion 60 0.8 50% 80%

Mechanized 30% Conversion 15 12 80%

Labour CostsCosts perper HectareHectare forfor thethe DifferentDifferent SilvicultureSilviculture TechniquesTechniques

ImprovementImprovement Enrichment ReforestationReforestation Natural StandStand Manual Mechanized

Time Required (in years) per haha 10 10 66 44

Rotation (in yyears)ears) 25 45 35 25

Average Volume for Harvesting at End of Rotation 20 140 180180 180 (m'/ha)(m3/ha)

Labour Cost per m3m) for Timber (MD/m3)(MD/m') 1 0.4 0.5 0.2

Labour Needs for a 100 ha/year programme (M/year) 3 8 40 13

The technique of improvingimproving and enriching natural stands turns out to be the least costly inin termsterms of labour,labour, but takestakes the longestlongest time to bebe implemented. The improvementimprovement ofof naturalnatural standsstands isis aa ratherrather simplesimple technique,technique, which nevertherless requires that there be a sufficient abundance of commercial species,species, on the one hand, and the possibility for natural regeneration, on the other.

Mechanized reforestation isis costly, but itit isis easy to implement,implement, and produces high yields. Non-mechanized reforestation,reforestation, on the otherother hand, requires a very considerableconsiderable amountamount ofof manualmanual labour.labour. - 174 --

Obviously, the technical aspects havehave beenbeen subordinated herehere to an overall reviewreview ofof thethe forestryforestry issue,issue, andand are only relevant as a criterioncriterion for decision-making inin aa globalglobal managementmanagement strategy.strategy.

IS REFORESTATION PROFITABLE?PROFITABLE?

Although oftenoften criticizedcriticized forfor itsits highhigh costs,costs, intensiveintensive mechanizedmechanized reforestation remains,remains, nonetheless,nonetheless, anan interestinginteresting technique.technique. AA comparison ofof closed forests inin temperatetemperate zoneszones withwith tropical closed forests can teach us a great dealdeal inin thisthis regard.regard .

Operation Temperate ForestForest

Clearing and 200 000000 toto 150 000 to Planting 400 000000 CFA 250 000 CFA

Maintenance and 300 000 to 300 000 to Thinning 400 000000 CFA 400 000 CFA

The forestation costs are lower in thethe temperatetemperate zoneszones, I however,however, growtgrowthh is much lowerlower asas well.well .

Forest plantations inin humidhumid tropicaltropical zoneszones offeroffer numerousnumerous advantagesadvantages with regard toto growthgrowth andand productivity.productivity.

Initial growth is veryvery strong,strong, withwith thethe maximummaximum volumevolume incrementsincrements reached withinwithin 55 toto 1515 years forfor tropicaltropical species,species, asas againstagainst 5050 toto 1001 00 years for tropical species, as against 50 to 100100 years forfor temperatetemperate species. InIn point ofof fact,fact, thethe exploitableexploitable ageage isis considerablyconsiderabl y lowerlower inin tropicaltropical zones,zones, at equalequal exploitableexploitable diameters.diameters. ItIt isis 1010 yearsyears lowerlower forfor biomassbiomass productsproducts (pulp, fuelwood),fuelwood), and between 2020 andand 5050 yearsyears forfor timber.timber.

Reforestation ExploitaExploitableble Total Timber Average Timber Species Age (Years)(Years) Volume Increment (m3/ha) (m3/ha/yr)

Douglas 65 390 6.0 Epic6aEpicea 110 510 4.6 Maritime PinePine 60 140 2.3

Frak6Frake 25 230 9.2 Cedar 28 253 9.0 Teak 60 330 5.5

During the same amount of timetime necessary forfor one rotation for a fast-fast­ growing temperatetemperate speciesspecies suchsuch asas Douglas ,Fir, two rotations of FrakeFraké or CedarCedar species can be obtained, and consequently, one-and-a-half timestimes more timber. This ratratioio increases in the case of conventional reforestation speciesspecies suchsuch as EpicéaEpicea oror MaritimeMaritime pine. As a result, the timber yieldyield from the reforestation of tropicaltropical speciesspecies isis actually twotwo toto fourfour times greater thanthan that obtained fromfrom temperatetemperate species.species . - 175l75 --

Nevertheless, referencereference hashas oftenoften beenbeen mademade toto thethe lowlow raterate ofof returnreturn from forest planting in the tropics, and this has frequently beenbeen used as a justification forfor abandoningabandoning thisthis technique.technique.

There are a number of different reasons for the present-day dissatisfaction withwith reforestationreforestation efforts.efforts. InIn thethe firstfirst place,place, itit shouldshould bebe noted that thisthis techniquetechnique hashas notnot alwaysalways beenbeen employedemployed inin aa correctcorrect manner:manner : the site must always bebe matchedmatched toto thethe species.species .

Structural causes are sometimes at the root ofof thethe problemsproblems associatedassociated with unsatisfactory end resultsresults ofof reforestationreforestation efforts inin humidhumid zones.zones. AA correct time-table mustmust be established for the operatioperations,ons , andand itit mustmust be observed. High quality plantplant materialmaterial adaptedadapted toto thethe sitesite mustmust bebe plantedplanted atat the correct time, andand carefullycarefully maintainedmaintained thereafter.thereafter.

The mostmost difficultdifficult problemproblem atat the presentpresent timetime is the lack ofof financially remunerative outletsoutlets thatthat might justify forestry investments.investments. This problem, however, goes farfar beyond the forestry sector alone, and involves a considerable number ofof otherother rawraw materials.materials .

The question wewe mustmust askask ourselvesourselves then,then, is wwhathat is actual worthworth ofo f this stumpage.stumpage. When we knowknow thisthis wewe cancan planplan forfor thethe conservationconservation andand management ofof tropicaltrdpical forestforest resources:resources: whosewhose rolerole isis notnot merelymerely toto produceproduce timber.

The third vital pointpoint we mustmust notnot forgetf o rget isis thatthat forestf o rest treestrees areare aa 'permanent andand long-termlong-term cropcrop notnot ideallyideally suitedsuited tot o financial speculation.speculation. TheThe forests real role goes farfar beyondbeyond meremere patternspatterns ofof production.production.

As a biological component, thethe forest directldirectlyy affeaffectsc ts the equilibrium of our environment.environment.

Natural or planted forestsforests induceinduce manymany ecologicaleco logical and socio-economicsocio-economic effects that are difficult toto graspgrasp andand quantify.quantify.

Within this frameworkframework then,then, fforesto rest rehabilitationrehabilitation throughthrough refreforestationo restat i on is no longerlonger aa simplesimple financialfinanc ial operationoperation for direct prprofit,o fit , and such ana n approach would imply aa truncatedtruncated versionversion ofof reality.reality.

The technical grounds forfor tropicaltropical forestforest reforestation mainly favourfavour a focus on bush fallows thatthat havehave alreadyalready beenbeen cleared.cleared.

Compared toto temperate zones,zones, thethe investmentinvestment returnreturn forf o r rotationrotation isis atat least twice as high for identical establishment costs.c o sts. TheThe realreal problemproblem lieslies in thethe veryvery lowlow commercialcommercial valuevalue ofof thethe commodity:c ommodity: investmentinve stment inin forestforest therefore in no way rivals investments in otherother,, more profitable, crops. It is quitequite probableprobable that the increasing scarcity ooff this multiple-rolemultiple-role resource could lead to a reassessent of its commercial value. The interests at stake are not only financial.financial.

The currentcurrent internalinternal raterate of returnreturn forf o r reforestationreforestation inin temperatetemperate zones does not top 4% for spespeciesc ies whose rotatirotationon takes 50 years,years, and the priceprice of m3 of standing timber isis 15 000000 FrancsFrancs CFA/m3CFA / m3 (Epic6a,(Epicea, Fir,Fir, DouglasDo uglas Fir).Fir) .

The internal rate of returnreturn forfor thethe samesame valuevalue ofof m3m3 ofof stumpagestumpage ofof identical exploitable sizesize cancan gogo asas highhigh asas 10%10% forfor speciesspecies suchsuch asas Fraké,Frake, Cedar, Framiré,Framire, etc.etc . -- 176 --

InfactIntact it isis veryvery difficultdifficult to limitlimit thethe discussiondiscussion to a financialfinancial analysis based onon thethe meremere marketmarket valuevalue ofof woodwood andand onon long-termlong-term maturities.maturities.

The veryvery rationalerationale forfor reforestationreforestation isis anan implicitimplicit admissionadmission ofof failure: of ourour inabilityinability toto preservepreserve thethe naturalnatural forest.forest.

While isis ourour urgenturgent tasktask todaytoday toto protectprotect aa portionportion of thethe naturalnatural formations fromfrom totaltotal destruction by correct forest management,management, reforestation remains the principal tool,tool:, in manymany cases,cases, forfor rapidlyrapidly establishingestablishing productionproduction forests. TheThe managementmanagement ofof naturalnatural formationsformations isis extensiveextensive byby itsits veryvery nature.nature. As a less expensive method of operation, itit abundantly satisfiessatisfies thethe need forfor protection, conservationconservation andand production.production.

The prime function of reforestationreforestation is production,production, whichwhich impliesimplies aa veryvery high outlayoutlay forfor establishment.establishment. ExEx situsi tu conservationconservation ofof geneticgenetic resourcesresources through conservation plantationsplantations isis anotheranother functionfunction ofof reforestation.reforestation.

Recent trials have shown thatthat a considerable number of natural forestforest species can bebe planted. BehaviouralBehavioural teststests inin CateCote d'Ivoired1rvoire demonstrateddemonstrated thatthat the LinguéLingue (Afzelia africana),africana) , the BétéBete (Mansonia altissima),al tissima) , the TiamaTiama (Entandrophragma(Entandrophrayma angolense), and thethe PouoPouo (Funtumia(Funtumia africana),africana), cancan toleratetolerate full light. DuringDuring theirtheir initialinitial periodperiod ofof growthgrowth (an(an averageaverage annualannual 0.500.50 -- 1 m), careful maintenance isis needed for only 5 to 77 years, to allow them to break free fromfrom thethe regrowth.regrowth.

People have actually planted trees for several millenia now. Foresty and agriculture areare thethe twotwo sidessides of resourceresource renewal of the plants mankind finds useful for'itsfor' its needs.needs.

The growing potential ofof thethe material means forfor forestforest clearing poses the problem of howhow toto conserveconserve ourour forestforest heritageheritage and howhow toto renewrenew it.it. Reforestation isis aa technicaltechnical aspectaspect ofof thisthis problem.problem.

As forfor thethe financialfinancial aspect,aspect, itit wouldwould bebe usefuluseful toto askask ourselvesourselves atat this point whether thethe applicationapplication ofof thethe internalinternal raterate ofof returnreturn toto forestsforests is justifiable, andand whether itit doesdoes notnot legitimize,legitimize, inactioninaction inin thethe sector.sector.

This problem callscalls intointo discussion thethe economic assessement ofof forestry interventions. TheThe parameterparameter ofof timetime isis aa heavyheavy factorfactor inin forestry projects. Can one really evaluate long-termlong-term forestryforestry operationsoperations withwith short-termshort-term tools?tools?

We endorse LESLIE'sLESLIE1s view (1987),(19B7), that "the legitimacy of anan especiallyespecially low interest rate forfor forests has, like the zero interest rate, been rejected by most economists, butbut thisthis doesdoes not prove that the idea is necessarilynecessarily a badbad one"one". .

Although thethe financialfinancial aspect of thethe questionquestion hashas anan exaggeratedexaggerated importance today, wewe mustmust not loselose sightsight ofof thethe factfact thatthat thethe lifelife spanspan ofof aa tree of ten farfar exceeds thethe lengthlength ofof oneone humanhuman generation.generation. FiftyFifty yearsyears ago,ago, tropicaltropical forestersforesters werewere alreadyalready plantingplanting trees.trees. WereWere theythey visionaries,visionaries, oror utopians?

Recent history has shownshown howhow clear-sightedclear-sighted theythey were:were: wewe gratefullygratefully harvest thethe fruitsfruits ofof theirtheir labourslabours today,today, knowingknowing thatthat wewe tootoo mustmust continuecontinue to plant treestrees forfor thethe future.future. - 177177 --

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1. BIBLIOGRAPHY ON ENRICHMENT PLANTATIONS

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DE NEEFNEEF P.P. (1972). SambaSamba cuttingcutting trialstrials in 1970-1971. TrialsTrials on woody plant stock. CTFT-CICTFT-CI 88 p.p.

DE NEEF P. (1972).(1972). Sylviculture enen for'étforet dense.dense. SemisSemis etet plantations.plantations. CTFT-CI. 80 p.p.

DE NEEFNEEF P.P . (1973) Supplementary note ono n SambaSamba cuttingcutting trials.trials. CTFT-CI.CTFT-CI .

DEREIX C., MAITRE H.F. (1977).(1977) . Thinning ofof SambaSamba plantations inin Sangoué.Sangoue. CTFT-CTFT­ CI. 2222 p.p. - 184 -

DIABATE K.K. (1976)(1976) CatalogueCatalogue ofof provenance trials andand speciesspecies trials of Pines and Eucalyptus atat SanSan Pedro.Pedro. CTFT-CI.CTFT-CI. 4343 p.p.

DIABATE K.K. (1977). Results of provenance trials of Pinus OocarpaOoc:arpa SchiedeSc:hiede planted inin 1971-721971-72 atat SanSan Pedro.Pedro. CTFT-CI.CTFT-CI. 8p.8p.

DIABATE K.K. (1980). Improvement of Pinus caribaeacaribaea inin IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI. 9 p.p.

DOUMBIA F.F. (1985). NotesNotes on the second thinning of mixed plots of Fraké-Frake­ FramireFramiré 19761976 atat Sangoué.Sangoue. CTFT-CI.CTFT-CI. 2323 p.p.

DOUMBIA F. (1987).(1987). ThinningThinning andand measurementmeasurement ofof thethe 19751975 CedrelaCedrela spacingspacing trialtrial at Sangoué.Sangoue. CTFT-CI.CTFT-CI. 1010 p.p.

DOUMBIA F.F. (1987). 1969 Cedrela behaviour plot atat Mopri.Mopri. FellingFelling results.results. CTFT-CI. 1212 p.p.

DOUMBIA F.F. (1990). Cubic content rates for plantation Samba. CTFT-CI.CTFT-CI. 2020 p.p.

DUPLAT P., PERROTE G.G. (1981).(1981). InventoryInventory andand appraisalappraisal ofof forestforest standstand growth.growth. ONF. Technical Section.Section. 403403 p.p.

DUPLAT P., TRAN-HA M.M. (1986)(1986).. DominantDominant height growth models.models . ONF. TechnicalTechnical Section. 3434 p.p.

DUPUY B.B. (1982). Results of experiments with some fast-growingfast-growing speciesspecies inin thethe Edea region.region . IRA/CRF.IRA/CRF. 6565 p.p.

DUPUY B.B. (1983). Notes on Ilomba in evergreen closedclosed moistmoist forest.forest. IRA/CRF.IRA/CRF. 4 p.p.

DUPUY B.B. (1984). ResultsResults in 1983 ofof thethe growth of OkoumeOkoumé plantations in thethe South KienkeKienk6 forestforest reservereserve (Kribi-Cameroon).(Kribi-Cameroo n). IRA/CRF.lRA/CRF. 6060 p.p.

DUPUY B. (1984). International provenance trial of Cordia alliodora.alliodora. SangoueSangoué trial. CTFT-CI. 33 p.p.

DUPUY B.B. (1985). Timber-orientedTimber-oriented plantations andand mixed speciesspecies associations: obobjectivesjectives and silviculturalsilvicultural constraints.constraints. CTFT-CI.CTFT-CI. 1111 p.p.

DUPUY B. (1985).(1985). Provenance teststests of Gmelina arborea inin Ivory Coast. CTFT-CI. 18 p.p.

DUPUY B:B: (1985). Planting protocol forfor permanentpermanent placettes with a view to drawing up aa yieldyield table.table. CTFT-CI. 11 p.p .

DUPUY B.B. (198(1986).6). ElementsElements of methodology for yield table construction. CTFT-CTFT­ CI. 1313 p.p.

DUPUY B.B. (1986). Principal silvicultural rulesrules forfor timbertimber species.species. CTFT-CI.CTFT-CI. 112 p.p.

DUPUY B.B. (1986). Study ofo f planting methods: thethe casecase of Fraké.Frake. CTFT-CI. 1717 p.

DUPUY B.B. (1986). The effecteffect ofof thinningthinning intensityintensity onon thethe growthgrowth of of Fralch Frake trees.trees . CTFT-CI. 8 p.p. - 185 --

DUPUY B. (1986).(1986). Silvicultural rulesrules forfor FrakéFrake on plantations. CTFT-CI. 7 p.

DUPUY B.B. (1987)(1987).. Proposals for the adaptationadaptation ofof silviculturalsilvicultural rulesrules toto insuffacYendly thinnedthinned stands.stands. CTFT-CI.CTFT-CI. 1111 p.p.

DUPUY B. (1987). Gmelina arborea: aa reforestationreforestation speciesspecies withwith aa future.future. CTFT-CTFT­ CI. 1111 p.p.

DUPUY B.B. (1987).(1987) . ThinningThinning:: a necessity.necessity. CTFT-CI.CTFT-CI. 66 p.p.

DUPUY BB.. (1987). DecisionDecision criteriacriteria for timber-orientedtimber-oriented intensive reforestation projects. CTFT-CI. 14 p.

DUPUY B. (1988)(1988). . Thinning characteristics for some timber-oriented reforestation species.species. CTFT-CI. 5 p.

DUPUY B.B. (1988).(1988) . Study of thinningthinning proceduresprocedures (timing(timing andand intensity)intensity) for Cedrela odorata. CTFT-CICTFT-CI 66 p.p.

DUPUY B. (1988).(1988) . Thinning characteristics for some timber-oriented reforestation species.species. CTFT-CI.CTFT-CI. 66 p.p.

DUPUY B.B. (1988)(1988). • .Elements Elements of silvicultural techniques forfor integratedintegrated standstand management. CTFT-CI. 8 p.p.

DUPUY B.B. (1988). Elements of silviculture forfor plantationplantation Badi.Badi. CTFT-CI.CTFT-CI. 22 p.p.

DUPUY B.B. (1989). AA plea for reforestation inin moistmoist tropicaltropical zones.zones. CTFT-CI.CTFT-CI. 1212 p.

DUPUY B.B. (1990). Behaviour of 37 Ivory Coast Coast closed closed moist forest moist species forest species planted with nono cover.cover. ResultsResults afterafter 1010 years of trialstrials inin transitionaltransitional evergreen/semideciduous forestforest (Mopri).(Mopri). CTFT-CI.CTFT-CI. 1111 p.p.

DUPUY B.B. (1990). Behaviour ofof 34 Ivory Coast closedclosed moistmoist forestforest speciesspecies planted wwithith no cover.cover. ResultsResults afterafter 1010 yearsyears ofof trialstrials inin semi-deciduoussemi-deciduous closed forest (Sangoué).(Sangoue). CTFT-CI.CTFT-CI. 1616 p.p.

DUPUY B.B. (1990). Teak growth and productivity inin IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI. 66 p.p .

DUPUY B. (1990).(1990). StudiesStudies ofof Teak growth andand productivityproductivity inin IvoryIvory Coast.Coast. YieldYield tables. CTFT-CI. 20 p.p.

DUPUY B.,B., N'GUESSAN.N'GUESSAN. (1991) Gmelina arborea in IvoryIvory Coast.Coast. YieldYield tables.tables, CTFT-CI. 2525 p.p.

DUPUY B.,B. , N'GUESSAN, DOUMBIA F.F . (1986).(1986). Evolution of dominant height on FrakeFraké plantations: definition of productivity classes.classes. CTFT-CI.CTFT-CI. 14 p.

DUPUY B.,B. , DOUMBIA F.F. (1986). CubicCubic contentcontent rates for plantation Fraké.Frake. CTFT-CTFT­ CI. 66 p.p.

DUPUY B., DOUMBIA F.,F., N'GUESSANN'GUESSAN K.K. (1987). Provisional yield table forfor FrakéFrake (Terminalia superba) in Ivory Coast. CTFT-CI.CTFT-CI. 2626 p.p.

DUPUY B., B., DOUMBIADOUMBIA F., F., N'GUESSAN K., CABARET N. (1988). Provisional yield table for Cedrela odorata in Ivory Coast. CTFT-CI.CTFT-CI. 2323 p.p. - 186 --

DUPUY B.,B., CABARET N., N'GUESSAN K.K. (1989).(1989). Provisional yieldyield tabletable forfor FramiréFramire (Terminalia ivorensis)ivorensis) inin IvoryIvory Coast. CTFT-CI.CTFT-CI. 2121 p.p.

DUPUY B.,B., DOUMBIA F.F . (1990).(1990). PlantationPlantation growthgrowth studiesstudies ofof SambaSamba (Triplochiton(Triplochiton scleroxylon). ProvisionalProvisional yieldyield tables.tables. CTFT-CI.CTFT-CI. 3737 p.p.

DUPUY B., AUGOUAUGOU A.A. (1990). Behaviour ofof 47 Ivory Coast closed moist forestforest species planted with nono cover.cover . ResultsResults afterafter 88 yearsyears ofof trialstrials inin evergreenevergreen closed forestforest (Yapo).(Yapo). CTFT-CI.CTFT-CI . 1717 p.p .

DURAND P.Y. (1980). The technologicaltechnological properties ofof Cordia alliodora.alliodora. CTFT-CI. 7 p.p.

DURAND PP.Y.. Y. (1984).(1984). The technology of Teak in IvoryIvory Coast. CTFT-CI.CTFT-CI . 5656 p.

DURAND P.Y. (1984). TheThe technologicaltechnological propertiesproperties and utilizationutilization possibilitiespossibilities of 59 Ivory Coast forestforest species.species. CTFT-CI. 191933 p.p .

DURAND P.Y.P . Y. (1985).(1985). NomenclatureNomenclature ofof IvoryIvory CoastCoast treetree species.species . CTFT-CI. 1111 p.

DURAND P.Y.P . Y. (1985).(1985). Some technological trial resultsresults concerningconcerning thethe principalprincipal reforestation speciesspecies ofof IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI. 2121 p.p.

DURAND P.Y.,P . Y., EDI KOUASSIKOUASSI A.A. (1984). PhysicalPhysical and mechanical properties of Caribbean Pines (p.(P . caribaeacaribaea andand P.P . oocarpa)oocarpa) planted inin IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI . 27 p.p.

DURAND P.Y., EDI KOUASSIKOUASSI A.A. (1985). PhysicalPhysical and mechanical properties of plantation SambaSamba agedaged 1313 yearsyears (Mopri(Mopri 1970).1970). CTFT-CI.CTFT-CI. 2323 p.p.

FARGEOT C. (1984). Pilot afforestation centre at Limba.Limba . Results of the first three campaigns.campaigns . CTFTCTFT Congo.Congo . 4949 p.p.

FAURE J.J.,J.J . , VIVIEN J.J. (1985). Trees and closed forestsforests ofof CentralCentral Africa.Africa. MinistMinist.. of Cooperation, Paris.Paris. 562562 p.p .

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GALIANA A.A. (1986). The floralfloral biologybiology ofof thethe FrakéFrake (Terminalia('Terminalia superba):supe rba): phenological obserobservationsv ations and sexualsexual reproduction study.study. CTFT-CI. 3434 p.

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GOUDET J.P.J.P . (1973). Silvicultural studystudy ofof the principalprincipal commercialcommercial treetree species. CTFT-CI. 2828 p.p.

GOUDET J.P.J . P. (1973).(1973). SilviculturalSilvicultural techniques.techniques . CTFT-CI.CTFT-CI. 4646 p.p.

GOUDET J.P.,J . P., GUINAUDEAUGUINAUDEAU F.F. (1986).(1986) . PlantationPlantation study of Mahogany. PlotPlot 1952.1952. N'Zida Forest.Forest . CTFT-CI. 3030 p.p.

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HUET J.J. (1966). Plantations in closed forest. PreparationPreparati on of forestsforests forfor enrichment. CTFT-CI. 1010 p.p.

JOLIVET EE.. (1983). Introduction to mathematic models toto biology. INRA.INRA . Masson. 148 p.p.

RADIOKADIO A.A. (1987). Study of the rooting conditions of herbaceousherbaceous cuttingscuttings ofof Samba under mist. CTFT-CI.CTFT-CI. 1515 p.p.

KAnIOKADIO A.A. (1988). Results after nine months ofof cloningcloning trialstrials onon SambaSamba atat Mopri. CTFT-CI.CTFT-CI . 1988.1988. 1717 p.p.

KADIORADIO A.A. (1990). Genetic improvementimprovement ofof GmelinaGmelina arboreaarborea L.L . in IvoryIvory Coast.Coast. Results and prospects.prospects . CTFT-CI.CTFT-CI. 1818 p.p .

KANGA L.HB.L . HB. (1985). Epicerura pergriseapergrisea Hampson,Hampson, the majormajor defoliatordefoliator ofof Terminalia inin IvoryIvory Coast.Coast . BiologyBiology andand counter-measures.counter-measures. CTFT-CI.CTFT-CI. 1515 p.p.

KOFFI KONAN J.C. (1987).(1987). ElementsElements ofof silviculturesilviculture forfor CedrelaCedrela odorata.odorata. ENGREFENGREF/CTFT-CI/CTFT-CI 6767 p.p.

KOFFI KONAN JJ.C.,.C., BERTAULT J.G.J.G . (1989).(1989). Notes on the growth and productivity of Pouo inin closedclosed moistmoist forestforest inin IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI. 1616 p.p.

KOYO JJ.P.. P. (1985). Planting of cuttings and morphogenetic variabilityvariability ofof clones of TermTerminaliainalia superba).superba). EnglerEngler andand DielsDiels oror LimbaLimba ofof thethe Southern Congo. SouthSouth Paris University thesis. OrsayOrsay Centre,Centre, 147147 p.p .

LANIER L.L. (1986)(1986).. Summary of silviculture. ENGREF. 468468 p.p.

LEGARE D. (1990). InfluenceInfluence ofof thethe subsoilsubsoil andand cuttingcutting plantingplanting techniquestechniques onon the rooting of cutting of Triplochiton scleroxylonscleroxylon at La TeneTéné station. CTFT­CTFT- CI. 1717 p.p .

LESLIE AA.J.. J. (1987)(1987) Economic aspectsaspects ofof tropicaltropical forestforest management.management. UnasylvaUna sylva 155 (39). 46-58.

MALAGNOUX M.M. (1975)(1975).. SymposiumSymposium on the variability of the Samba (Triplochiton(Triplochitoll scleroxylon) and its propagationpropagation andand improvementimprovement techniques.techniques . BFT8FT (164).(164) . 25-3025-30

MAILLARD D.D. (1978). PropagationPropagation byby cuttings ofof the Limba and varvariousious closed forest speciesspecies.. CTFT-Congo. 5959 p.p .

MAITRE H.F.,H.F . , DEREIXDEREIX C.C. (1977)(1977).. HeightHeight increments of Teak stands inin relationrelation to site fertility. CTFT-CI.CTFT-CI. 1717 p.p.

MAITRE H.FH.F.. (1978).(1978). Results of artificial pruning trials on Teak at Matiemba and Seguie.Seguié. CTFT-CI. 1010 p.p.

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MAITRE H.F. (1979).Cordia(1979). Cordia alliodora.alliodora. ProgressiveProgressive spacingspacing trialstrials atat Sangou6.Sangoue . CTFT-CI. 44 p. p .

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MAITRE H.F.,H.F., MALLETMALLET B.B. (1980). Plantation FramiréFramire inin IvoryIvory Coast.Coast. CTFT-CI.CTFT-CI. 8 p.p.

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MALLET B.B. (1978)(1978).. Notes onon inter-provenanceinter-provenance phenologicalphenological variabilityvariability inin Terminalia superba.superba. CTFT-CI.CTFT-CI. 44 p.p.

MALLET B.B. (1981).(1981) . TheThe presence ofof root-rotsroot-rots onon Cedrela odorataodorata inin IvoryIvory Coast.Coast. CTFT-CI. 55 p.p.

MALLET B.B. (1979)(1979).. A.C.P.A.C.P. study of the action of aqueous extracts andand FramiréFramire litter and root residues on thethe growth andand mineralmineral compositioncomposition ofof saplings.saplings. CTFT-Cl/ORSTOM,CTFT-CI/ORSTOM, 9393 p.p.

MALLET B.B. (1983).(1983) . NotesNotes on the problems of TerminaliaTerminalia ivorensisivorensis A. CHEV. in Ivory Coast. CTFT-CI.CTFT-CI. 33 p.p.

MALLET B.B. (1983). Weeding of mechanizedmechanized forestforest plantationsplantations inin IvoryIvory Coast.Coast. CTFT-CI. 1212 p.p.

MALLET B.B . (1983).(1983). Pre-emergency herbicideherbicide useuse inin mechanized forestforest plantations in IvoryIvory Coast. CTFT-CI.CTFT-CI. 1313 p.p.

MALLET B. (1983).(1983) . The chemical upkeep of young mechanised forest plantations in IvoryIvory Coast. FutureFuture prospectsprospects andand presentpresent realities.realities. CTFT-CI.CTFT-CI. 1010 p.p.

MALLET B. (1984). The fertilisation of forest plantations:plantations: some forecasts for Ivory Coast. CTFT-CI.CTFT-CI. 1818 p.p .

MALLET B.B. (1986). TheThe entomologicalentomological problems of forest plantations in IvoryI vory Coast. CTFT-CI.CTFT-CI. 1414 p.p .

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MARTINOT-LAGARDE P.P. (1961). ReforestationReforestation withwith Azobe,Azobé, FramireFramiré and Cassia in lower IvoryIvory Coast. WatersWaters andand Forests.Forests. 1111 p.p .

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N'GUESSAN A.A. (1987). Cubic content rates forfor GmelinaGmelina arborea.arborea. CTFT-CI.CTFT- CI. 11 p.p. - 189 --

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SANGARE M. (1990)(1990).. Contribution to the establishment of the forestry management plan forfor the Yapo-AbbéYapo-Abbe forestforest stand.stand. SODEFOR.SODEFOR. 107107 p.p .

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FAO FORESTRYFORESTRY PAPERSPAPERS

1 Forest utilization contracts on public land, 19771977 30 Tropical forest resources,resources, 19821982 (E IE FF S)5) IE(E F SI5) 31 Appropriate technology in forestry, 11982 982 (E)IE) 2 Planning forest roadsroads andand harvestingharvesting systems,systems, 32 Classification and definitionsdefinitions ofof forest products,products, 1977 (EIE FF S)5) 1982 (Ar/E/F/S)IAr/E/F/S) 3 World list ofof forestryforestry schools, schools, 19771977 (E/F/S) (E/F/S) 33 Logging of mountain forests, 19821982 (E (E FF S)5) 3 Rev.Rev. 1. World list ofof forestryforestry schools,schools, 19811981 (E/F/S) (ElF/51 34 Fruit-bearing forest trees, 19821982 (E (E FF S)5) 3 Rev.Rev. 2. World list ofof forestryforestry schools,schools, 19861986 (E/F/S) (E/F/S) 35 Forestry in China, 1982 (C(C E)E) 4/1 World pulppulp andand paperpaper demand,demand, supplysupply andand tradetrade 36 Basic technologytechnology in forest operations, 1982 (EIE FF S)5) -- Vol.Vol. 1,1. 1977 1977 (E IE FF S)5) 37 Conservation and developmentdevelopment ofof tropical forest 4/24/2 World pulppulp andand paperpaper demand,demand, supplysupply andand tradetrade resources, 1982 (EIE FF S)5) -- Vol,Vol. 2,2.1977 1977 (E IE FF S) 5) 38 Forest productsproducts pricesprices 1962-1981,1962-1981, 19821982 (E/F/S) (E/F/S) 5 The marketing of tropical wood,wood, 19761976 (E (E S)51 39 Frame saw manual, 1982 (E) (E) 6 National parks planning.planning, 1976 IEIE F S··)S* 40 Circular saw manual, 19831983 (E)IE) 7 Forestry for local community development, 1978 41 Simple technologietechnologiess forfor charcoal making, 1983 IArlAr EE FF S)5) IE(E F S)5) 8 EstablishmentEstablishment techniques forfor forest plantations, 42 Fuelwood supplies in the developing countries, 1978 (ArIAr CC E*E" FF S)S) 1983 (ArIAr EE FF S)S) 9 Wood chips - production,production. handling,handling, transport,transport. 43 Forest revenue systems in developingdeveloping countries,countries, 19761C1976 (C ES)E 5) 1983 (EIE FF S) 1010/1/1 Assessment of logging costs from forest 44/1 Food and fruit-bearing forestforest speciesspecies inventoriesinventories inin thethe tropicstropics - 1.,. Examples Examples fromfrom easterneastern Africa,Africa, 19831983 (E IE FF S)SI - 1.1. Principles Principles andand methodology,methodology, 19781978 (E(E FF S)S) 44/244/2 Food and fruit-bearing forest speciesspecies 10/210/2 Assessment of logging costs from foreforestst - 2.2. Examples Examples fromfrom southeasternsoutheastern inventoriesinventories inin thethe tropicstropics Asia, 19841984 (E IE FF S)5) - 2.2. Data Data collectioncollection andand calculations,calculations, 19781978 (EIE FF S)SI 44/3 Food and fruit-bearingfruit-bearing forest speciesspecies - 3.3. ExamplesExamples 11 Savanna afforestation in Africa, 19771977 (E IE F1FI from Latin America, 19861986 (E IE SISI 12 China: forestry supportsupport for agriculture,agriculture, 19781978 (E)(E) 45 EstablishingEstablis hing pulp and paper mills, 1983 (E)(EI 13 Forest products prices 1960-1977, 19791979 (E/F/S) (E/F/S) 46 Forest products prices 1963-1982, 19831983 (E/F/S) (E/F/S) 14 Mountain forest roadsroeds andand harvesting, 19791979 (E)(E) 47 Technical forestry education - designdesign andand 1414 Rev. 11.. Logging and transport in steep terrain, 19851985 (E)(E) implementation,implementation. 19841984 (E (E FF S)S) 15 AGAGRIS RIS forestry forestry -- world cataloguecatalogue of informationinformation 48 Land evaluation for forestry, 19841984 (C (C EE FF S)51 and documentation services,services, 19791979 (E/F/S) (E/F/S) 49 Wood extraction withwith oxenoxen andand agriculturalagricultural 1616 China: integrated wood processingprocessing induindustries,stries, 19791979 tractors, 19861986 (E (E FF S)S) (EIE F S)S) 50 Changes inin shshiftingifting cultivation in Africa, 19841984 (E IE F)F) 17 Economic analysis ofof forestryforestry projects, 1979 50/1 Changes inin shiftingshifting cultivation in Africa (EIE F S)S) - sevenseven case-studies,case-studies, 19851985 (E) IE) '717 Sup. 1. Economic analysis ofof forestry projects:projects: 51/1 Studies on the volume and yield of tropical forestforest case studiesstudies,, 19791979 (E IE S)SI stands - 1. 1 . DryDry forestforest formations,formations, 19891989 (E (E F)F) 1717 Sup. 2. EconomicEconomic analysis of forestry projects:projects: readings,readings , 52/1 Cost estimating inin sawmillingsawmilling industries:industrie s: guidelines, guidelines, 1980 (CIC E)E) 1984 (E)IE) 18 Forest products prices 1960-1960-1978,1978, 19801980 (E/F/S) (E/F/S) 52/2 FieldFi eld manual on cost estimation inin sawmillingsawmilling 19/1 Pulping and paper-making properties of industries, 19851985 (E) (E) fast-growing plantationplantation woodwood species species 53 Intensive multiple-usemUltiple-use forestforest managementmanagement inin ,Kerala, - Vol.Vol. 1,1. 19801980 (E) IE) 1984 (EIE FF S)S) 1919/2/ 2 Pulping and paper-making properties of 54 PlanificaciónPlanificaci6n del dedesarrollosarrollo forestalforestal,, 1984 (S)(5) fast-growingfast-growing plantationplantation woodwood speciesspecies 55 IntensiveIntensive multiple-usemultiple-use forestforest managementmanagement inin thethe - Vol.Vol. 2,2. 19801980 (E) IE) tropics,tropics. 19851985 (E IE FF S)51 20 Forest tree improvement, 19851985 (C (C EE F F S)S) 56 Breeding poplars for disease resistance, 19851985 (E) (E) 20/2 A guideguide to forestforest seedseed handling,handling, 19851985 (E IE S5 )) 57 wood - processingprocessing andand use,use, 19851985 (E (E S)S) 21 Impact on soils of fast-growingfast-growing speciesspecies inin lowlandlowland 58 Sawdoctoring manual,manual, 19851985 (E(E S)S) humid tropics, 19801980 (E IE FF S)5) 59 The ecological effects of eucalyptus, 1985 22/12211 Forest volume estimation and yield prediction IC(C E F S)S) - Vol.Vol. 1.1. Volume Volume estimation,estimation, 19801980 (C IC EE FF S)51 60 Monitoring andend evaluation ofof participatory forestry 22/2 Forest volume estimation and yield prediction projects, 19851985 IE IE F F S1 S) - Vol.Vol. 2.2. YieldYield prediction,prediction, 19801980 (C (C EE FF S)51 61 Forest productsproducts prices 1965-1965-1984,1984. 19851985 (E/F/S) (E/F/SI 23 Forest productsproducts prices 1961-1980, 19811981 (E/F/S)(E/F!5) 62 World list ofof institutionsinstitutions engagedengaged in forestry andand 24 Cable lloggingogging systems, 1981 (CIC ElEI forest productsproducts research,research, 19851985 (E/F/S) (E /F/S) 25 Public forestry administrations in Latin America, 63 Industrial charcoalcharcoel making, 19851985 (E)IE) 1981 (E)IE) 64 Tree growing by ruralrural people, 19851985 (Ar(Ar EE FF S)SI 26 FForestryore stry and rurelrural development, 1981 (E(E FF S)5) 65 Forest legislation in selected African countries,countries, 27 Manual of forest inventory,inventory, 19811981 (E(E F)FI 19861EF)1986 (E F) 28 Small and medmediumium sawmills in developing countries, 66 Forestry extension organization, 1986 (C(C EE S)S) 1981 (EIE S)S) 67 Some medicinal forestforest plants of Africa andend Latinlatin 29 World forest products,products, demanddemand and suppsupplyly' 1990 990 America, 1986 (E)(E) and 2000.2000, 19821982 (E IE FF SIS) 68 AppropriateAppropriete forest industries, 19861986 (E) IE) 69 Management ofof forestforest industries.industries, 1986 (E)(E) 92 Forestry policies in Europe -- an analysis,analysis. 1989 (E)IE} 70 Wildland fire management terminology, 1986 93 Energy conservation in the mechanical forest IE(E/F/S)/F/SI industries, 19901990 (E (E S)51 71 World compendium of forestry andand forest productsproducts 94 Manual on sawmill operationaloperational maintenance,maintenance. researchresearch institutions,institutions, 19861986 (E/F/S) (E/F/S) 1990 (E)lEI 72 Wood gas as engine fuel, 19861986 (E(E S)5) 95 Forest productsproducts pricesprices 1969-1988,1969-1988, 19901990 (E/F/S) (E/F/S) 73 Forest products:products: world outlookoutlook projectionsprojections 96 Planning and managing forestry research:research: guidelinesguidelines 1985-2000, 19861986 (E/F/S) IE/F/SI for managers, 1990 (E)IE) 74 Guidelines forfor forestryforestry information processing,processing, 97 Non-wood forest products: thethe wayway ahead, ahead. 19861986 (E)lEI 1991 (ES)IE SI 75 An operationaloperetional guide to the monitoringmonitoring andand 98 Timber plantations inin thethe humid tropicstropics of Africa, evaluation ofof social forestry in India,India. 19861986 (E)IE) 1993 (EIE F)FI 76 Wood preservation manual, 1986 (E)(E) 99 Cost control in forest harvestingharvesting andand roadroad 77 Databook on endangered tree and shrub species construction, 19921992 (E)IE) and provenances, 1986 (E)IE) 100 Introduction to ergonomicsergonomics in forestry inin developingdeveloping 78 Appropriate wood harvesting in plantation forests, countries.countries, 1992 (E)(E) 19871987 (E)lEI 101 Management and conservationconservation of closed forests inin 79 Small-scale forest-based processing enterprises, tropical America,America. 19931993 (E(E FF S)51 1987 (EIE FF S)SI 102 Research managementmanagement inin forestry,forestry, 19911991 (E)(E) 80 Forestry extensionextension methods,methods, 1987 (E)(E) 103 Mixed and pure forestforest plantations in the tropics andand 81 Guidelines forfor forestforest policy formulation, 19871987 (C IC E)EI , 19921992 (E) IE) 82 Forest products prices 1967-1986, 19881988 (E/F/S) (E /F/S) 104 Forest productsproducts pricesprices 1971·1990,19921971-1990, 1992 (E)(E) 83 Trade inin forestforest produ,tsproduos:: aa studystudy ofof thethe barriersbarriers 105 Compendium of pulppulp andand paperpaper trainingtraining andand faced by the developing countries, 19881988 (E)(E) research institutions,institutions, 19921992 (E) IE) 84 Forest products:products: world outlookoutlook projectionsprojections 106 Economic assessment ofof forestry projectproject impacts,impacts. 19871987-2000· 2000 - productproduct andand countrycountry tables, 1988 1992 (E)lEI IE/F/SI(E/F/S) 107 Conservation of genetic resources in tropical forest 85 Forestry extension curricula, 19881988 (E/F/S)(E/F/S) management: PrincipPrinciplesles and concepts.concepts, 1993 (E)IE) 86 Forestry policies in Europe,Europe, 1988 (E)(E) 108'08 A decade of wood energy activities within thethe 87 Small-scale harvestingharvesting operationsoperations of wood and Nairobi Programme ofof Action, 19931993 (E) IE) nonnon-wood-wood forest products involvinginvolving ruralrural people,people, 19881E1988 (E FF S)SI Availability: June 1993 88 Management of of tropicaltropical moistmoist forestsforests in Africa, 1989 (EIE FF P)PI Ar Arabic Multil - MultilingualMultilingual 89 Review of forest managementmanagement systems of tropicaltropical C Chinese OutOut ofof printprint Asia, 1989 (E)(E) E English ** In preparationpreparation 90 Forestry and foodfood security, 19891989 (Ar (Ar E E S) S) F French 91 Design manual onon basic wood harvesting P Portuguese technology, 1989 IE(E FF S)S) S Spanish (Published onlyonly as FAOFAD Training Series,Series. No. 18)18) ThsThe FAO TschnicalTechnical PapsrsPapers ars are availablsavailable throughthrough thsthe authorizsdauthorized FAO Sa/ssSales AgentsAgents or dirsctlydirectly from'rom DistributionDistribution andand Sales Se/ss Section,Section, FAO, VialeVials delle TermeTerms di Caracalla,Cerece//(I, 00100 Rome, Italy.Ita/y.