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THE MANAGEMENT OF FORESTS FOR TIMBER AND NON-WOOD FOREST PRODUCTS IN CENTRAL AFRICA

Sarah A. Laird

1. Introduction

Logging is the main economic activity in the forests of Central Africa, and increasing portions of the forest area are allocated to timber concessions. Given the large and growing role of timber production in the economy of Central African forests, it is important that an examination of the value of NWFPs in local economies, and their potential incorporation into conservation and development projects, include the relationship between the harvest of NWFPs and timber.

Timber and NWFPs are inter-related in a range of ways. In some cases, timber species have important non-timber uses, and logging will reduce availability of these species as locally or regionally consumed NWFPs. Destructive logging operations can also cause direct damage to species in residual stands and those that make up the understorey and ground cover of forests, many of which are important NWFPs. Subsequent silvicultural treatments, when they are applied, can reduce species diversity by promoting an increased proportion of commercial species, and removing competing "undesirables", many of which might be NWFPs. On the other hand, logging can open up habitats for the many NWFPs that prefer disturbed sites and secondary forest.

By reducing the structural and species diversity of a forest, logging and silvicultural treatments can also produce a number of largely as yet unknown ecological repercussions. These may include reductions in numbers of pollinators, seed dispersers, alterations in plant-herbivore relationships and the possibility that timber exploitation may ultimately produce conditions in which it is difficult for many forest species to regenerate (Peters, 1996). Since a wide range of NWFPs are generally harvested from a given forest area, reductions in species diversity over the long-term can directly affect the consumption and trade patterns of local people dependent upon NWFPs for their livelihoods.

On the positive side, however, the integration of timber and NWFPs into multi-purpose systems of natural forest management can both minimize the negative impacts of timber extraction and capitalize on the many benefits provided by a range of forest products. Calls for management plans for Central African forests on the part of governments and international development agencies, and recent developments in forest product certification and conservation project approaches in the region, argue for a closer examination of the relationship between timber, the primary cash earner, and NWFPs of central importance to local economies, health, and cultures.

This paper will briefly address some of the components of the timber-NWFP relationship in Central Africa, including:

· Species that yield both NWFPs and timber;

· The impacts of logging operations on NWFPs; and

· The incorporation of the NWFP-timber relationship into management plans for sustainable forest management.

1.1. Scale of activity

Timber and NWFPs are often artificially separated in examinations of forest management, since local people will manage the forest for both types of products. Some researchers have suggested that discussions should not be organized around a timber/NWFP dichotomy, but should instead address forest management at the level and scale of inputs and outputs in relation to small holder livelihoods (Padoch and Pinedo-Vasquez, 1996). The distinction should be made, therefore, between:

· Commercial and industrial exploitation; and

· Small-holder, small-scale exploitation.

Commercial, industrial scale timber exploitation represents the bulk of logging volume in Central Africa. NWFPs, on the other hand, with the exception of a dozen or so medicinal species harvested for phytomedical or pharmaceutical export markets such as Pausinystalia johimbe and Prunus africana, tend to be harvested for small holder subsistence consumption or for sale in local markets (Cunningham et al., 1997; Cunningham and Mbenkum, 1993; Sunderland et al., 1997).

Well-established regional markets for forest spices, medicine, chewsticks, kola nuts, and forest foods, are also significant, and form what might be thought of as an intermediate band of resource exploitation. For example, a large number of the NWFPs sold in markets in Bata, Equatorial Guinea, such as Afrostyrax spp., Ricinodendron heudelottii, Aframomum spp., Tetrapleura tetraptera, and Garcinia kola, are imported across sometimes great distances from Cameroon (Sunderland, 1998).

1.2. Timber production in Central Africa

In recent years, log exports from Central Africa have increased dramatically. For example, between 1996 and 1997, log exports from Cameroon increased by 47% (SGS Cameroun, S.A. 1997). Demand from Asia accounted for the bulk of this increase in the 1990s, as supplies of domestic timber declined in that region. By 1997, Asian countries took 85% of log exports from Equatorial Guinea, and half of log exports from Cameroon. Log exports to Asian countries - including China, Japan, The Philippines, India, Taiwan, and Hong Kong - increased from 23.5% of total exports from Cameroon in 1996 to 49.5% of the total in 1997 (SGS Cameroun, S.A. 1997; Projet CUREF, 1997). Although greater emphasis has recently been placed on the domestic transformation of wood products by governments, the bulk of exports continue to be in the form of unprocessed logs.

Recently the economic crisis in Asia has dampened demand from this region for Central African timber. Japanese imports of Gabonese hardwoods, for example, had already declined by 68% from 1996 to 1997, and Thailand's imports declined by 39% (SEPBG, 1997). At the same time, however, significant increases in log exports from Cameroon to a number of European countries were also reported, including to Italy (the largest importer of Cameroon logs), France, Spain, and Germany (SGS Cameroun, S.A. 1997). Although a decline in demand from Asia might significantly affect exports of Central African timber in the short-term, it is likely that overall global demand for industrial wood will continue to rise.

2. Timber and NWFP species

The most direct connection between timber and NWFPs is when a single species has both timber and non-timber value. In many cases, this results in diminished availability of species for non-timber uses, although in some cases the impact is minimal, or harvests of NWFPs and timber are complimentary. For example, Aucoumea klaineana (okoumé), the primary timber species exported from Equatorial Guinea (85% in 1997) and Gabon (70% in 1997), yields a resin which is tapped prior to felling for timber and collected to make torches (which are then wrapped in the bark of Xylopia aethiopica, an NWFP with a range of uses).

Table 1. Cameroon Log Exports by Species: January-September 1997 (SGS Cameroun, S.A., 1997)

Species (scientific name)

Trade name

Volume (m³)

Triplochiton scleroxylon

ayous

412 186

Entandophragma cylindricum

sapelli

136 564

Terminalia superba

fraké

112 145

Erythrophloeum ivorense

tali

102 287

Tetraberlinea bifoliata

ekop

66 540

Lophira alata

azobé

63 503

Milicia excelsa

iroko

55 456

Distemonanthus benthamiamus

movingui

39 690

Canarium schweinfurthii

aiele

29 788

Baillonella toxisperma

moabi

27 944

Nauclea diderrichii

bilinga

26 219

Entandophragma utile

sipo

25 773

Eribroma oblonga

eyong

23 947

Pterocarpus soyauxii

padouk

19 987

Pericopsis elata

afrormosia

18 433

Ceiba pentandra

ceiba

18 387

Lovoa trichiliodes

bibolo

12 475

Guibourtia tessmannii

bubinga

11 454

Daniella ogea

faro

10 966

Guarea cedrata

bosse

10 207

Cylicodiscus gabunensis

okan

10 091

Terminalia ivorensis

framire

9 762

Khaya ivorensis

mahogany

9 343

Other

 

72 830

TOTAL =

 

1 372 445

Of the top 25 timber species exported from Cameroon in 1997 (see Table 1), most have non-wood values. However, for each species the relationship between timber and NWFP values varies due to factors such as variations in species density and distribution, timber value and the level of local demand for NWFPs. For example, species such as Baillonella toxisperma (moabi), Pterocarpus soyauxii (padouk), and Milicia excelsa (iroko) which have high timber values and are found unevenly distributed in low densities, are usually heavily depleted in areas where logging takes place. Meanwhile, their local NWFP values are high, and there are no ready substitutes for some of the more valuable products they yield. As a result, there is a significant conflict between NWFP and timber values.

Baillonella toxisperma is one of the more valuable timber species in the region, used in furniture and cabinet making, flooring and for veneer. In 1997, it was the tenth most important commercial timber species exported from Cameroon by volume (SGS, Cameroun, S.A., 1997). This, despite being found in notoriously low densities of less than 1 tree/hectare. The seed of B. toxisperma also produces a cooking oil so prized, and today so scarce, it is rarely sold in markets since local communities prefer to keep what they can collect for their own use. The seed oil is also used medicinally, including for skin problems and rheumatism.

Pterocarpus soyauxii (padouk, or camwood) is used to make furniture and in cabinet-making. Locally, it is a preferred wood in some areas for carving canoes, stools, musical instruments and agricultural implements, and the ground stem is also an important cultural and medicinal species associated with childbirth and marriages, used mainly by women. Due to selective logging pressure, it has become scarce in many forest areas. Milicia excelsa is one of the most sacred tree species in Central and West Africa, and is used medicinally. It is heavily depleted due to selective logging pressures, and in some countries, such as the Congo, is endangered (WCMC, 1994; Laird et al., 1997).

Other valuable timber species with important non-timber uses include: Nauclea diderrichii (bilinga), a very strong timber, resistant to borers and used for harbour work, mortars and general construction. The bark, root, and wood are all used to make a yellow dye, and the bark is also used to treat fevers and stomach problems (Brown, 1978; Mabberley, 1989; Abbiw, 1990; Laird et al., 1997). Canarium schweinfurthii (aiele) has a range of uses as timber, and also yields popular fruits sold in local markets and a resin which is burned as incense and to start fires (thus the name "bush candle"). Lophira alata (azobé or ironwood) was the sixth most important timber species by volume exported from Cameroon in 1997, and is also used locally as a medicine for back and toothache.

In a study in southern Cameroon, it was found that of the 31 timber species exploited by the Dutch logging company, GWZ, 19 (representing 86% of volume) are also used by local communities. Baillonella toxisperma was cited by 60% of local people as a NWFP seriously affected by logging, followed by Guibourtia tessmannii (bubinga), used locally for cultural and medicinal purposes, and Entandophragma cylindricum (sapelli), used locally for construction. Other NWFP species cited as directly affected by demand for a species' timber value include Terminalia superba (fraké), Milicia excelsa (iroko), Lophira alata (azobé) and Lovoa trichiliodes (bibolo) (van Dijk, 1997).

Figure 1. A pile of Pausinystalia johimbe bark in a logging concession. Harvesting of the bark of this species usually follows timber logging operations (Photo: T. Sunderland).

Table 2. Medicinal values of selected timber species in Cameroon

Selected results from the Limbe region, SW Province, Cameroon (Laird et al, 1996)

SPECIES

Common/

pilot name

Top timber species

(Cameroon and Limbe)2

Med.

Use (Y/N)

Plant parts used in medicine (roughly in order of importance)

Status in Limbe region

Aningeria robusta

aniegre

Cameroon/Limbe

N

no common medicinal uses

* +

Afzelia bipindensis

doussie

Cameroon/Limbe

N

no common medicinal uses

**

Albizia zygia

lantanza

Limbe

Y

bark, stem, fruit, leaves

*

Alstonia boonei

stoolwood

Limbe

Y

bark, latex, leaves

**

Autranella congolensis

mukulungu

Cameroon

N

no common medicinal uses

 

Baillonella toxisperma

moabi

Cameroon

Y

bark, seed oil, rootbark

 

Canarium schweinfurthii

aiele

Cameroon/Limbe

Y

resin, bark, fruit

*

Chrysophyllum africana

abam

Limbe

Y

fruit, bark

*

Ceiba pentandra

ceiba, boma

Cameroon

Y

bark, leaves, fruit, roots

 

Coelocaryon preussii

ekoume

Limbe

Y (minor)

bark

**

Distemonanhus benthamianus

movingui

Cameroon

Y

bark, leaves

 

Entandrophragma cylindricum

sapelli

Cameroon/Limbe

N

no common medicinal uses

* +

Entandrophragma utile

sipo

Cameroon

Y

bark

 

Entandrophragma angolensis

tiama, timbi

Limbe

N

no common medicinal uses

** +

Enantia chlorantha

enantia, moambe jaune

Limbe

Y

bark

*

Eribroma oblonga

eyong

Cameroon

N

no common medicinal uses

 

Erythrophleum ivorense

tali

Cameroon

N

no common medicinal uses

 

Gossweilerodendron balsamiferum

tola

Cameroon

Y

stem exudate

 

Guibourtia tessmannii

bubinga

Cameroon

Y

bark, leaves

 

Khaya ivorensis

acajou, African mahogany

Cameroon

Y

bark, roots, seed

 

Lophira alata

ironwood, azobe

Cameroon/Limbe

Y

bark, leaves

*

Lovoa trichilioides

dibetou

Cameroon

N

no common medicinal uses

 

Milicia excelsa

iroko

Cameroon/Limbe

Y

barks, leaves, stem exudate

** +

Mansonia altissinia

mansonia, bete

Cameroon

Y (minor)

bark, root

 

Microberlinia bisulcata

zingana, zebrawood

Limbe

N

 

** (west coast)

Nesogordonia papaverifera

kotibe

Cameroon

N

no common medicinal uses

 

Nauclea diderrichii

bilinga

Cameroon/Limbe

Y

bark, leaves, root

**

Pericopsis elata

assemela, afrormosia

Cameroon

N

no common medicinal uses - P. laxiflora commonly used

 

Piptadeniastrum africanum

dabema, atui

Limbe

Y

fruit, leaves

**

Poga oleosa

poga

Limbe

Y

seed oil, seed

**

Pterocarpus soyauxii

padouk, camwood

Cameroon/Limbe

Y

stem, bark, leaves

** +

Pycnanthus angolensis

ilomba

Cameroon/Limbe

Y

bark, leaves, seed

**

Staudtia stipitata

niove

Limbe

N

no common medicinal uses

**

Sterculia oblonga

eyoung

Limbe

N

no common medicinal uses

* +

Sterculia rhinopetala

nkanang

Limbe

Y (minor)

bark

**

Terminalia superba

frake, limba

Cameroon/Limbe

Y

bark, leaves, fruit

**

Triplochiton scleroxylon

obeche, samba

Cameroon

N

no common medicinal uses

 

Tiegemella hechelii-africana

douka

Cameroon

Y (minor)

bark

 

Status of species exploited in the forest west-southwest-south of Mount Cameroon, encompassing Mount Etinde, and stretching along the coast from Idenau, through Limbe, to Mabeta-Moliwe, according to Akogo et al (1994):

+ = valuable timber species limited in distribution due to past selective exploitation;

*(*) = species (most) commonly exploited for timber in forest area (1988-94)

In the Mount Cameroon region, more than half of the most valuable timber species exploited between 1988 and 1994 were also shown to have significant medicinal and other non-timber values (See Table 2). These include: Alstonia boonei, Milicia excelsa, Canarium schweinfurthii, Nauclea diderichii, Poga oleosa, Pterocarpus soyauxii and Terminalia superba. Most of the widely marketed NWFPs in Central Africa, however, including Irvingia gabonensis, Afrostyrax spp., Tetrapleura tetraptera, Ricinodendron heudelottii, Garcinia kola, Gnetum africanum, and Monodora myristica are not important timber species (Laird et al., 1996; Ndoye et al., 1997; van Dijk, 1997; Sunderland, 1998).

3. The impact of logging operations on NWFPs

Logging operations directly affect both present and future harvests of timber and NWFPs. They can lead to declines in species and forest structural diversity, and to unfavourable rates of basal area growth of species through destruction of seedlings, adolescent trees, soil surface and drainage patterns (John 1992; Dykstra and Heinrich 1992; Whitmore 1991). Studies in the eastern Amazon, for example, found that to extract 52 m³/ha, or eight trees, logging operators destroyed 26% of those trees remaining. Canopy cover, a summation of road area, felled tree area, and log storage area, might be reduced by half following logging (Johns, 1988; Uhl and Vieira, 1989). Logging damage to the soil surface, including the removal of topsoil, disturbance and soil compaction, can retard the growth of both NWFP and timber species.

Logging roads cause direct damage, and in poorly planned operations might occupy anywhere from 6-20% of the forest area (Uhl and Vieira 1989; Johns 1992; Jonson and Lindgren 1990). Perhaps the largest impact of logging roads on NWFPs, however, is through the access they provide to once inaccessible populations of wildlife and other NWFPs, as well as to markets. This helps people to capitalize on the market potential for previously inaccessible NWFPs, but can lead to over-exploitation of species (Wilkie et al., 1992; Dahaban, Nordin and Bennett 1992; Caldecott 1989).

Damage in selective harvesting systems is usually patchy, due to varying population densities of commercial species. NWFP species with limited geographical ranges, poor dispersal ability and few seedlings in the understorey are generally less equipped to deal with logging pressures. Rare and specialized species will generally suffer most from the random damage of logging operations and the shift in species composition to generalists that often follows immediately upon logging (John, 1992; Cunningham, 1992; Peters, 1994; Laird, 1995; Peters, 1996).

It is clear, however, that logging can positively affect a suite of NWFP species that prefer disturbed forest areas and roadsides. In Central Africa , these include rattan species, as well as many condiment and medicinal species such as Aframomum spp. (used to spice stews, treat coughs and as important magnifying agents in medicinal mixtures), Piper guineensis (used as a spice in stews, to treat hangovers, stomach problems and to build strength), and Piper umbellatum (used as a wrapping for cooking).

Commonly used medicinal herbs found along logging roads and in disturbed forest patches also include: Costus afer (the stem is chewed to relieve coughs and sore throats, and the juice is used to treat eye infections); Emilia coccinea (used as an anti-poison, for jaundice and snakebite); and Eremomastax speciosa (used to purify and strengthen the blood). In southern Cameroon, logging appeared to cause abundant regeneration of the condiment species Ricinodendron heudelotti, and to have limited impact on the size class distribution of Irvingia gabonensis (van Dijk, 1997).

Figure 2. Fruits of Aframomum spp. (Photo: S. Laird)

A number of other important NWFP species - such as the medicinals Senna (Cassia) alata (a pan-tropical species the leaves of which are used as a treatment for ringworm and other skin ailments) and Spilanthes filicaulis (flowers chewed for toothache) - are found on the peripheries of villages and in gardens. Others - such as Kigelia africana (used for stomach problems, to treat snakebite and eye infections, and for a range of cultural and protection purposes) and Alstonia boonei (bark and latex used to treat fever and promote lactation), Dacryodes edulis (the fruits are a popular food) - have been brought from the forest and are planted in villages. For this range of NWFP species, logging will obviously have little immediate impact.

NWFPs are sourced from a range of habitat types, and traditional systems of management for forest resources make use of a continuum of vegetation types including recently cleared land, farm fallows, secondary forest, and forests which have not been cleared for hundreds of years. While most commonly-used medicinal plants are sourced from secondary forest, the edges of paths, farms, village peripheries and informal gardens kept by specialist healers, species used for more severe illnesses, and many of those species considered most powerful, are sourced from high or secondary forest (Thomas et al., 1989; Falconer 1990, 1994; Laird et al., 1996). Logging will directly affect only a portion of the range of NWFP species used by local communities, but the importance of this range and diversity in products, and the limits to substitution, should be recognized.

4. The NWFP-timber interface: Contributing to sustainable natural forest management

The harvest of timber and non-timber forest products can be incorporated into multi-purpose systems of natural forest management that both minimize the negative impacts of timber extraction and capitalise on the many benefits provided by a range of forest products. The vast majority of timber production in tropical countries comes from unmanaged forests. Rotations, regeneration periods, felling cycles, harvestable girth limits, etc. tend not to be based on the growth rates and regeneration requirements of the species, but on the demand for wood, so forests are usually harvested in excess of the allowable cut, and logging damage can be severe (Poore, 1989; Nair, 1991; Wadsworth, 1987). However, in managed forest areas timber and NWFPs can be harvested in a complimentary manner (Salick, 1992; Malhorta et al., 1991).

Timber harvest plans can be based on inventories and the collection of information necessary to ensure sustainability and to plan transportation within the forest in a way that minimizes damage to residual stands and the total area disturbed by roads, landings and skid trails. Timing of logging operations can take into consideration rainy seasons, seedfalls and the reproductive cycles of animals and species of non-wood value. Complimentary harvests of NWFPs prior to and post logging can be planned, including the harvest of rattans, collection of oil-producing seeds and medicinal barks, and tapping essential oils and resins from valuable timber species. The harvest of NWFPs in conjunction with logging operations is often done now on an ad hoc basis, but these activities could be built into management plans, such as those called for in Cameroon as part of Community Forests, an innovation of the January 1994 Law No. 94/01 concerning Forests, Wildlife and Fisheries (GoC, 1994; GoC, 1997; Laird and Lisinge, 1998).

Management plans, and attention to multiple use, are also incorporated into international efforts to provide economic incentives for sustainable forest management. Recently, the Forest Stewardship Council - the main accreditation body for timber from natural and plantation forests - has begun exploring the role of NWFPs in timber production through an NTFP Working Group. A draft Principle governing NWFPs is under discussion. In addition to highlighting the need for sustainable management plans for NWFPs, the draft Principle requires that: "11.3 Management plans that prioritize timber production should include specific provisions to describe and minimize short and long-term impacts on NTFPS;" and "11.6 The monitoring of timber harvesting should evaluate impacts on non-timber resources and the forest ecosystem. Monitoring should also include the impacts of non-timber forest products on timber resources" (FSC NTFP Working Group, 1997).

Unfortunately, quantitative data on the relationship between timber and non-timber uses and management is difficult to come by, although some studies do exist which attempt to evaluate changes in community ecology variables with logging, damage, regeneration, and silvicultural treatments both for useful plant species and for the plant community as a whole (Salick et al., 1992; Salick et al., 1995; Peters 1996; van Dijk, 1997; Shanley et al., 1998). Ecological, socioeconomic, legal, policy and cultural aspects of timber and NWFP harvesting and use must then be brought together in order to examine the relationship between timber and NWFPs, and the conservation of tropical forests and the resources contained within them.

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2 The most exploited timbers in Cameroon according to FMRP (1993) and SGS (1997); 22 most exploited timbers in Limbe region according to Akogo et al. (1994).

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