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GULF OF GUINEA ISLANDS' BIODIVERSITY
NETWORK
THE EXPLOITATION OF PRUNUS AFRICANA ON THE ISLAND OF BIOKO, EQUATORIAL GUINEA
A Report for the People and Plants Initiative, WWF-Germany and the IUCN/SSC Medicinal Plant Specialist Group, June 1999
Terry C. H. Sunderland and Charles Tanyi Tako
ABSTRACT
The bark of the montane trees species, Prunus africana is utilised for the treatment of benign prostate hyperplasia, and has a current market value of around $150 million per annum. (Cunningham et al., 1997). Until 1992, the exploitation of Prunus bark was concentrated primarily in Cameroon, Kenya and Madagascar, Tanzania and, to a lesser extent, the Democratic Republic of Congo (ibid.). However, recent reports have indicated that the island of Bioko, Equatorial Guinea is becoming of increasing importance for the supply of Prunus bark to Europe and may become increasingly important as sources of supply from other countries become scarce or are subject to increased regulation. This report presents the findings of a field-based study of the exploitation of Prunus africana on Bioko in the latter part of 1998.
1. INTRODUCTION
1.1. EQUATORIAL GUINEA
The Republic of Equatorial Guinea consists of three diverse and disparate territories (see Figure 1); the island of Bioko (2,017 km²), the mainland territory of Rio Muni (26,017 km²) and the island of Annobon (17 km²). It is a former Spanish colony, gaining independence in 1968, but the results of a tumultuous post-colonial era led to the country being classified as one of the poorest in Africa (Liniger-Gomez, 1988). The recent discovery of large oil deposits, however, and the opening of the country to foreign timber exploiters, have recently changed the fortunes of this relatively unknown African enclave and the country is forecast to become one of the most prosperous in sub-Saharan Africa (Goldman, 1998).
Equatorial Guinea has a combined population of around 400,000. This population is composed of a number of tribal groups which were traditionally distributed along geographical lines. The Fang and the Ndowe originate from the Rio Muni region and the Bubi, the island of Bioko. However, much migration by the Fang from the mainland has seen the Bubi become a minority on Bioko. Other Africans are also present in significant numbers in Equatorial Guinea. These include Cameroonians (mostly Hausa traders), Nigerians, and Ghanaians as well as small numbers of people from Chad and Mali. The majority of these people are engaged in small-scale trading and business (Sunderland and Obama, 1999.).
Figure 1. The Republic of Equatorial Guinea consists of three diverse and disparate territories; the island of Bioko (2,017 km²), the mainland territory of Rio Muni (26,017 km²) and the island of Annobon (17 km²).
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1.2. THE ISLAND OF BIOKO
The rectangular-shaped island of Bioko, formerly Fernando Póo, lies 32 km from the coast of Cameroon. It is oriented north/south and measures roughly 75 by 25 km, with a total land area of 2,020 km². The island is the largest in the Gulf of Guinea and forms part of a volcanic chain which includes Mount Cameroon, São Tomé and Principé and Annobon. Bioko island itself is dominated by three volcanic peaks, Pico de Basilé (3,010m) in the north, and Pico Biao (2,010m) and Gran Caldera de Luba (2,261m) in the south. The majority of the lowland forest skirting the highlands, with the exception of the extreme south of the island, has been converted to cocoa plantations, but in many areas the majority of the original canopy trees have been maintained to provide shade. Some commercial logging was undertaken in the lowland forest of the southern half of the island during the early 1990’s, but this has now ceased. The montane forest and alpine savannah have experienced relatively little physical disturbance aside from some coco-yam cultivation in the immediate vicinity of settlements (Juste and Fa, 1994; Collel and Maté, 1994).
1.3. BIODIVERSITY
Bioko is unique in terms of its fauna, with a number of important sub-species of primate, in particular (Garcia and Eneme, 1997; Hearn et al., 1998). These include the drill (Mandrillus leucophaeus poensis), Pennant’s red colobus (Piliocolobus pennanti), the red-eared monkey (Cercopithecus erythrotis erythrotis) and Preuss’s monkey, (Cercopithecus preussii insularis), all of which are endemic. More widepread, but still rare species such as the black colobus (Colobus satanus satanus) and the crowned monkey (Cercopithecus mona pogonias), also occur on Bioko. Hunting for bushmeat is widespread and is currently considered the greatest threat to biodiversity (Collel and Maté, 1994; Juste, et al., 1995; Fa, et al., 1995; Garcia and Eneme, 1997; Hearn et al., 1998).
In terms of flora, Bioko has the highest number of taxa of all the Gulf of Guinea islands (1,105 species, representing 605 genera within 124 families), but due to its proximity to the mainland, has the lowest level of endemism (Figueiredo, 1994). In addition, a number of important families common on the mainland, are poorly represented on Bioko, notably the palms. The flora of Bioko is remarkable similar to that of the mainland, notably that of Mount Cameroon (Exell, 1952). The two mountains share a similar vegetation gradient; from lowland forest through to montane forest at mid-elevations, and alpine savannah at the summit.
For a more detailed description of the vegetation of Bioko see Exell, (1952); Fa (1992); Juste and Fa (1994); and Jones (1994). Recent in-depth faunal studies including the impact of the bushmeat trade include: Collel and Maté (1994); Fa (1992); Juste, et al. (1995), Fa, et al. (1995); Hearn et al., 1998).
1.4. ECONOMY
The colonial economy of Equatorial Guinea was dominated by the cultivation of cocoa (on Bioko) and timber exploitation (Rio Muni), and in the post-war era, it was one of the richest countries in Africa. During the tumultuous post-independence years and its isolationist regime, the collapse of the cocoa industry led to significant reliance on quick natural resource exploitation, notably timber and fisheries, often with no guidelines for environmental protection or for the rational use of resources. The impact on the environment was enormous and was further exacerbated by the needs of the population who were also forced to rely much more on forest products, particularly bushmeat (Castroveijo, et al., 1994). Since 1979, the economy has benefited from outside investment, and in particular, the discovery of large oil deposits (Goldman, 1998). The oil industry has the capacity to transform the fortunes of the country and has led to the country recently being labelled "petit Kuwait".
2. PRUNUS AFRICANA ON BIOKO
2.1. DISTRIBUTION
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Prunus africana is found throughout the montane forests of Bioko in two main areas. Although relatively patchy in distribution, the species seems to occur in an almost continuous band around the island within an altitudinal range of between 1,200m to 2,500m (Tomas pers. comm.). Despite this relatively widespread distribution, the bark of Prunus africana is currently only harvested from two key sites; along the road to the top of Pico de Basilé on the north side of the island, and around the village of Moca, on the southern end of the island. |
| Figure 2. The distribution of Prunus africana on Bioko. |
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2.2. LOCAL USE OF PRUNUS AFRICANA The traditionally dominant tribal group on Bioko, the Bubi, refer to Prunus africana as bihasa, and are reported to use the bark of the tree for a number of medicinal uses (Garcia and Eneme, 1997; Hearn et al., 1998; Sunderland and Obama, 1999). However, there is, understandably, a certain reticence to share knowledge of this traditional use and many local people interviewed as part of this study stated that they did not know the tree had any value before they became aware that it was being harvested commercially. This does not correspond with our field observations that Prunus africana trees are conserved during the clearance of forest for the development of coco-yam farms; a practice that seems rooted in long-standing tradition. The fact that Prunus bark is sold in a number of local pharmacies is also testament to the local importance of this species (Sunderland and Obama, 1999).
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| Figure 3. Montane forest environment on Bioko. | Figure 4. Medicinal plant stall in Malabo selling, among other things, Prunus africana bark. |  |
2.3. CHEMICAL COMPOSITION AND GENETIC VARIATION
The chemical composition of Prunus africana bark on Bioko is very similar to that of the resource on Mount Cameroon. The bark exhibits the same mean variation in compound concentration as would be expected from a montane environment with many ecotones and micro-climates (del Vecchio, pers. comm.). However, studies on the genetics and bark chemistry of Prunus africana (Dawson, 1997; Barker et al., 1995) suggest that while, in terms of commercial acceptability, the bark from both Bioko and Mount Cameroon are similar, it is likely that with Prunus africana populations on Bioko being isolated from those on montane "island" populations , there may be considerable genetic and chemical differences in this population. This will need further examination.
3. LEGISLATION AND PROTECTED AREAS
3.1. FORESTRY LEGISLATION
The 1997 Appendix to the 1995 Forestry Law of Equatorial Guinea (Reglamento de Aplicacion de la Ley Sobre el Uso y Manejo de los Bosques EQG/96/002) makes reference to the sustainable management of commercially exploited NTFPs such as Prunus africana and Piper guineensis (Articulo 62º). Despite showing a will to ensure the sustainable exploitation of Prunus africana, and other high-value forest products, this objective is hindered by a considerable lack of adequate base-line information on abundance and distribution. A general lack of knowledge as to how to manage and exploit the resource in situ also inhibits the potential for sustainability.
The EG Forestry Department have set an annual export quota for Prunus bark at 500 tonnes per annum. This figure has been arbitrarily set in consultation with the CITES authority in Malabo and is not based on any inventory or resource assessment as neither have been undertaken to date. In addition, despite the intentions to ensure good management of the resource, there is currently no minimum diameter size for exploitation of Prunus and the stripping of young trees <20cm in diameter is commonplace. As has been the case in Cameroon, the issue of permits is not necessarily a guarantee of sustainability, especially when permits are issued and no harvesting controls are ever implemented.
3.2. PROTECTED AREAS
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A network of protected areas for Equatorial Guinea was proposed in the 1988 forestry legislation. Ley 8/1988 outlines the protection of nine main zones, which cover around 340,000 ha, or 8.2%, of the total land surface of the country. This network has been substantially modified in recent years by the
EU-funded Proyecto Conservacíon y Utilizacion Racional de los Ecosistemas Forestales
(CUREF) based in Bata, through the designation of appropriate levels of protection for each area. Proposed extensions have also been recently made to many of these protected areas
(República de Guinea Ecuatorial, 1998).
The two major protected areas on Bioko contain the bulk of the Prunus africana resource on the island (Garcia and Eneme, 1997). Pico Basilé is currently proposed to be afforded National Park status. This will ultimately mean that no settlement be allowed with the protected area nor will exploitation of the majority of the forest resources be able to take place. However, for high value forest products, such as Prunus africana, as long as exploitation is underpinned by a long-term management plan based on sound inventory data, some regulated harvesting would be able to be undertaken. The southern area of the island, including the Caldera de Luba, Lago Biao and the settlement of Moca is to be protected as a Scientific Reserve. This designated protection status means that no exploitation of any sort will be allowed within the defined boundaries of the reserve itself. |
| Figure 5. Proposed protected areas on Bioko. |
3.3. CITES LEGISLATION
Prunus africana was added to CITES Appendix II in 1994, becoming effective in 1995. In theory, this means that countries of export have to issue export permits and countries of import have to check these permits upon entry (Cunningham, et al., 1997). The Scientific Authority of an export country advises its Management Authority on the sustainability of a consignment and, ideally, the export permit would be based on sound inventory and management information (so-called "non-detriment" findings (ibid.)). All of the countries exporting Prunus africana bark, including Equatorial Guinea, are signatories to CITES. This should ultimately mean that the bark entering the EU is harvested from a sustainable source. However, the reality is somewhat different and, despite the legislation, the unsustainable exploitation of Prunus africana is well-recorded (see studies cited in Cunningham et al., 1997). Undoubtedly, quotas and permits are being issued without reference to adequate biological baseline information. Future action by CITES, and the EU in general, on this issue is currently under discussion.
The CITES Management Authority is based at the Minsterio de Bosques y Medio Ambiente in Malabo. The Scientific Authority for CITES in Equatorial Guinea is listed as Santiago Engonga Osono at the same address, and there is not in place a functioning and independent Scientific Authority for plants in Equatorial Guinea. Despite the fact the CITES permits are issued for Prunus africana bark export from Equatorial Guinea and the quotas are relatively small, there is still unsustainable exploitation of this resource on Bioko (see below). It should also be noted that the "Scientific Authority" in Malabo is being funded to complete a Masters thesis on the exploitation of Prunus africana on Bioko and one wonders about any potential conflict of interests.
4. THE EXPORT OF PRUNUS AFRICANA BARK FROM BIOKO
Currently, only one company exports the bark of Prunus africana from Bioko. Aprovechamiento Agricola (APRA) is a subsidiary of NATRA, a Spanish conglomerate concerned mainly with the export of agricultural products such as cocoa and coffee. APRA is a Spanish company but is registered in Equatorial Guinea. Local registration is a Government requirement in order to trade in the country. Although agricultural cash crops comprise the bulk of their exports (and income), in 1992, APRA began to look at the feasibility of exporting Prunus bark to diversify their commodity base in Equatorial Guinea. Commercial-scale harvesting operations began in 1992/3. Although official export data is only available from 1995, it is estimated that 200 tonnes per annum were exported from Bioko between the years 1992 and 1994 (J. Perez de Val, pers. comm.; Tomas pers. comm.). Initially, only dried, raw bark was exported, but in 1997, APRA began to macerate the bark into powder prior to export and increased the FoB value from 2.15 FF/kg to 4 FF/kg (see Table 1). All bark exported is shipped directly to Valencia, Spain exclusively through Mac ó Bessora shipping agents. The bark is then sold on from NATRA to EUROMED and then on to MADAUS in Germany.
Figure 6. Source of Prunus africana bark entering world market (adapted from Cunningham et al., 1997).
In contrast to Cameroon, Kenya and Madagascar, the amounts of Prunus africana bark currently exported from Bioko are still rather modest and do not even reach the 500 tonnes / annum quota set by the Equato-Guinean Government. Between 1992 and 1998, an average of 210 tonnes per annum were exported from Bioko.
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Table 1. Quantities and value of Prunus africana bark exported from Bioko by APRA
S.L. to Spain. (Source: Cámara Agrícola, Government of Equatorial Guinea).
Note: Numbers in italics are estimated (based on personal communications and projections and probably err on the high side). * For 1998, data is incomplete after August; projected export total was anticipated to be 120 tonnes. |
| Table 2. Statistics of bark harvesting: breakdown of taxes and commission per shipment of Prunus africana bark (Source: Ministerio de Bosques y Medio Ambiente). |
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APRA currently enjoy a monopoly on the exploitation of Prunus africana on Bioko – a situation that has probably contributed to the limited current exploitation of Prunus africana bark from Bioko, despite the unsustainable means of exploitation. A similar situation existed in Cameroon prior to 1987, when Plantecam Medicam, as it was known then, operated within a strict monopoly in the exploitation of Prunus africana. They set, and adhered to, strict harvesting guidelines such as no felling, no girdling and stripping of opposite quarters of the tree, allowing bark to regenerate. However, a breakdown in this situation, through the issue of licenses to a number of companies and individuals led to a dramatic increase in field operatives working in an area and a corresponding increase in unsustainable practices, notably the felling of trees and total bark removal.
Likewise, APRA’s monopoly is under threat from a number of outside interests with a long history of bark harvesting who also wish to harvest the rich Prunus resource on Bioko. It is unlikely that APRA will be the sole exploiter of Prunus bark from Bioko for much longer. This is despite the rigorous conditions currently set down by the Guinean Government which require foreign interests to register as Guinean companies as well as providing funds for a full inventory and development of an appropriate management regime (Tomas, pers. comm.). Undoubtedly, the presence of future commercial competition will cause a corresponding increase in the amount and intensity of bark exploited from Bioko and will have a significant, and probably negative, impact on the wild resource. This is especially the case if adequate management regimes, based on sound inventory data, are not established prior to the issue of licenses and the determination of quotas.
5. ASSESSMENT OF EXPLOITATION
5.1. FIELD METHODOLOGY
During the course of this study, a number of exploitation sites were visited with regular bark harvesters. On the south of the island in the vicinity of Lago Baio, a number of other Prunus africana populations which have not yet been exploited were also visited, in order to determine the effects of harvesting on the wild resource using a control population.
| During each field visit, the diameter at breast height of each individual in a population was recorded (150 trees representing 5 populations; 2 of which having been previously exploited and 3, as yet, unexploited). An assessment of crown health was also taken for each individual enumerated using a sliding scale of 0 to 5 (with 0 indicating 100% crown mortality and 5 indicating a healthy crown). In addition, bark thickness was measured in both exploited and unexploited populations to enable a comparison to be made between the bark thickness of exploited and unexploited populations.
5.2. CURRENT EXPLOITATION PRACTICES ON BIOKO Since 1995, when commercial harvesting of Prunus began, bark exploitation on Bioko has been limited to two main sites; the road leading to the summit of Pico Basilé and the forest in the environs of Moca, with harvesting beginning in the latter region in 1996. The main reason for this limited exploitation is that these areas are serviced by motorable roads; there are very few other sites elsewhere on the island where this is the case. Initially, the Forestry Department suggested that exploitation should occur on a rotational basis i.e. not in simultaneous sites, but this conditionality has broken down and both exploitation sites have been extremely active since 1995. For reasons outlined below, exploitation at both sites has currently ceased.
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| Figure 7. Measuring the dbh of large Prunus africana individual near Moca. |
5.2.1. PICO DE BASILÉ
The road to Pico Basilé lies within a protected military zone; at the summit is a radio relay station and TV antenna that services the whole of Equatorial Guinea. Along the roadside between 1,400m to 2,500m, occur large, often mono-dominant stands of emergent Prunus africana trees. Almost all the trees within 500m of the road have been harvested at some point in the past three years, some of which have been stripped of their bark more than once. Harvesting is undertaken by roving labourers engaged by APRA, often based in Malabo. The nearby village of Rebola was offered the opportunity to supply bark directly to APRA but disputes regarding the price of bark led to this proposal being shelved. It is important to note that village control of the forest on Pico Basilé is limited due to the strong domination of the State in land and security issues, hence the villagers have little or no recourse to imposed access to their forest environs by outsiders.
Although bark harvesting occurs within the immediate vicinity of the existing road, it has been reported that a number of new "roads" were established to facilitate the exploitation of Prunus bark (Hearn et al., 1998). It was also stated that these roads were also providing hunters further access to the forest which was having a debilitating effect on hunting (ibid.). However, our field observations determined that in fact these "roads" are in fact footpaths leading from the main Malabo to Pico Basilé road to populations of Prunus africana; an indication of constant and recurrent harvesting.
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In general, the harvesting of Prunus bark has been undertaken from standing trees. The majority of trees enumerated during our field work were stripped to a height of 3-4m only, and often around the whole bole, with the bark on the remainder of the bole and lower branches being left. APRA has provided a special tool to some of its harvesters for the stripping of bark which has led to significant cambium damage to the tree, lessening the capacity for bark regeneration and leading to significant individual and population senescence and crown die-back. This tool is more commonly used for the stripping of cork oak (Quercus suber) in Spain and is a flat-headed instrument that scrapes the bark from the tree rather than the normal cutting (by cutlass) and stripping of the bark in sections more commonly witnessed in Cameroon and elsewhere. The scraping action removes the cambial layer entirely and prevents immediate recovery of the tree. The exposed sapwood is also prone to stem borer damage which, in some cases, can be very severe, especially at lower altitudes (see Figure 13). |
| Figure 8: Stripped stem of Prunus africana on Pico Basilé. |
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Figure 9. Crown death of exploited trees Crown health is a good indication of overall tree health (Shigo, 1986; Shigo; 1994) and the observations by the field team recorded that even with bark harvesting being undertaken recently (since 1995), the crowns of many exploited trees are already displaying evidence of senescence and considerable die-back. In fact, 21% of exploited trees are actually dead, with a further 47% showing varying degrees of die-back and reduction in leaf area. Only 32% of the recorded trees could be classed as healthy, with many of these being the most recently-exploited individuals and probably not yet exhibiting the effects of bark harvesting. This high level of death and early senescence must be attributed to both the practice of ring-barking as well as the scraping of the bark, and removal of the cambial layer, during harvesting.Aside from stripping of standing trees, Hearn et al. (1998) report that a number of Prunus trees have been felled and fully stripped and, indeed, a number of cut stumps were witnessed during our field work. Some selective felling was undertaken by harvesters in 1996 but was noted by the Forestry Department and subsequently stopped. It says something about the power of the State in Equatorial Guinea that the recommendation to stop felling has since been strictly adhered to. In short, it is clear that current methods of stripping of standing Prunus africana individuals on Pico Basilé is affecting the long-term health of the population and is leading to incredible wastage in terms of potential harvestable bark.
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Figure 10. Cut stump of Prunus africana on Pico de Basilé. |
Figure 11. Crown assessment of Pico Basilé populations |
Figure 12. Size-class distribution of exploited trees on Pico Basilé. Note the absence of medium-sized tree due to felling and removal.
5.2.2. MOCA
Harvesting around the village of Moca began in early 1996. APRA have an unofficial representative in the village who co-ordinates the exploitation of Prunus bark, almost exclusively undertaken by young men from the village. Some areas around the community are classed as traditional forest and no intervention is allowed in these sacred groves. There are many unexploited Prunus africana individuals in these forest areas, despite their close proximity to the village.
| The majority of the exploitation is undertaken within 30m of the path from Moca to Lago Baio. Bark stripping, as on Pico Basilé, is undertaken only 3-4m up the bole, with the remainder of the bark remaining untouched. Ring-barking, or harvesting all around the bole, is common. However, the stripping of the bark is undertaken with a cutlass dividing the bark into sections and then actually stripping the bark away instead of using a scraping tool. Because the cambial layer is not destroyed, some callus bark growth is evident (see Figure 16). However, considerable crown senescence and death was observed. A recorded 4% of trees harvested since 1996 were dead and a further 93% showed considerable amounts of crown die-back and reduction in leaf area. Only 2.5% of trees showed no immediate crown effects of harvesting, although, again, these were the most recently harvested individuals. There has been some evidence of felling and complete removal of some older trees. Again, as on Pico Basilé, the Forestry Department has halted this activity. |  |
| Figure 13. Borer damage of stripped trees at lower altitudes. |
Figure 14. Assessment of crown health of Moca population.
Figure 15. Size-class distribution of exploited and unexploited populations at Moca.
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5.3. BARK PRICES PAID AND CURRENT LACK OF HARVESTING ACTIVITY From 1995 to 1997, APRA paid Prunus africana harvesters the sum of 25 CFA/kg for undried (wet) bark. After a number of complaints from many harvesters that this was too low, this figure was increased to 30 CFA/kg. With this level of remuneration, harvesters were often able, depending on the distance from village to exploitation site, to collect and transport around 100kg a day; a daily income of 3,000 CFA. However, as it became clear that regular harvesting of populations close to the village was not possible while bark reputedly recovered, harvesting began to be undertaken at much further distances into the forest into more and more unexploited populations. Because of this, the daily profit became less and less; hence the demands for increased revenues. In addition, more recently, the Forestry Department in Malabo has become aware of the range of prices paid to harvesters in Cameroon by Plantecam (60-110 CFA/kg) and this information has subsequently reached many of the Bioko-based harvesters. They are now demanding a comparable revenue to that paid in Cameroon and have requested 150 CFA/kg. APRA are not willing to pay anywhere near this for wet bark and a stalemate has been reached; there is no immediate prospect for a resolution of this issue. This means that, currently, no bark harvesting is taking place at all. The prospect of future competition for the sector may, however, stimulate the market once more, especially if any alternative party interested in exploitation of Prunus bark are willing to pay more than the current APRA levels of remuneration. |
| Figure 16. Callus bark regrowth on exploited trees in Moca. |
6. POPULATION STRUCTURE AND THE IMPACTS OF EXPLOITATION
6.1. SIZE-CLASS DISTRIBUTION
In general terms, the cumulative size-class distribution of Prunus africana on Bioko is comparable to that of the population on Mount Cameroon (see Figure 18) with a limited number of lower size-class individuals. Undoubtedly, this comparable size-class distribution is due to the tendency of the species to mast; that is to produce large quantities of fruit sporadically (perhaps every five to fifteen years) as much as from the stated effects of harvesting (Ndam, 1996).
Figure 17. Cumulative size-class distribution of Prunus africana on Bioko – exploited and unexploited populations.
However, there are some significant differences in population structure between exploited populations of Prunus africana and unexploited populations, probably due to the practice of felling trees prior to stripping. This is especially the case on Pico Basilé (Figure 12) where the effects of current harvesting are adversely affecting the health of the remaining population and its reproductive future. Similarly, the difference in structure between unexploited populations and exploited populations, especially in Moca, should be noted (see Figure 15) especially with regard to the high number of exploited trees in the lower diameter-classes.
Figure 18. Size-class distribution of unexploited Prunus africana on Mount Cameroon. (Source: Sunderland and Nkefor, 1997).
6.2 BARK THICKNESS
The measurements of bark thickness in both exploited and unexploited populations enable a direct comparison and the impacts of harvesting to be made. The mean bark thickness of unexploited populations is 16.21mm whilst the mean bark thickness in standing exploited populations (generally made on regrowth [callus] bark where found) is 9.94mm. These figures are consistent with field observations.
Figure 19. Bark thickness in exploited and unexploited Prunus africana populations.
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6.3. REGENERATION In general, regeneration is good, with large numbers of even-aged seedlings observed, especially on Pico Basilé. However, the recorded high mortality of Prunus africana seedlings is a contributory factor in the lack of recruitment and the recorded lack of pole stages. The seed technology and recruitment patterns of Prunus africana are dealt with in more details by Ndam (1996) and Sunderland and Nkefor (1997).
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| Figure 20. Copious seedlings of Prunus africana under parent tree. |
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6.4. CULTIVATION Despite being a relatively simple process to propagate Prunus africana from seed (Sunderland & Nkefor, 1997) there has been little cultivation of Prunus africana on Bioko. However, in early 1998, APRA funded the development of a small (170m²) village-based nursery in the village of Moca. This nursery consists of raised stock beds of wild-collected seedlings numbering around 2,000 individual 1+1 plants. It is intended to lift the wildings in early 1999 and distribute them to local farmer co-operatives for incorporation into coco-yam-based agroforestry systems. APRA will provide funds for the maintenance of the cultivated trees. The cultivation and artificial regeneration of Prunus africana is set to be a conditionality of future license allocation (Tomas pers. comm.). |
| Figure 21. Prunus africana nursery in Moca. |
7. FUTURE EXPLOITATION SITES
Despite the fact that current bark harvesting practices occur in only two main sites on Bioko, a number of other areas have been identified as being probable sites for future exploitation. Although these sites currently have no vehicular access, it has been stated that any increase in bark price would make exploitation at these sites more likely to be attractive to village-based exploiters and would undoubtedly lead to increased levels of exploitation throughout the island (Tomas pers. comm.).
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Table 4. Proposed future Prunus africana exploitation sites on Bioko |
8. CONCLUSIONS AND RECOMMENDATIONS
The exploitation of Prunus africana on Bioko is currently unsustainable. Despite the fact that the harvesting is still at rather modest levels, the impacts on the harvested populations are both significant and, in the long term, deleterious. The fact that there remain significant unexploited stands of Prunus africana in other parts on the island, makes the exploitation from Bioko that much more attractive to outside interests – many of whom are now trying to gain access to the resource.
It is highly recommended that a full-scale inventory and resource assessment of Prunus africana be completed on Bioko. This should be undertaken as soon as possible to allow the preparation of appropriate management plans to facilitate the introduction of the proposed protected area legislation. We are at a critical point in the exploitation of Prunus africana from Bioko; if an inventory and associated management plan are not undertaken and produced, the exploitation will undoubtedly follow the same pattern as the exploitation from other source countries that is, unsustainable harvesting, inadequate legislation and control, and, ultimately, the loss of the resource itself.
ACKNOWLEDGEMENTS
The authors are grateful for Tony Cunningham for proposing this study and to WWF-UK and to Mr Liersch at Madaus for funding the field work for TS. The Mount Cameroon Project provided financial support for TC. Frank Stenmanns and Juan-Enrique Garcia of CUREF, Bata, provided considerable background information on the legal aspects of Prunus exploitation and, along with Ramon Castilo of Asociación Amigos de Donaña, Malabo, provided considerable help and support with logistics. Uwe Schippman, Santiago Engonga and Jaime Pérez del Val provided invaluable advice about CITES control and the main areas of Prunus exploitation. Gerard del Vecchio of Plantecam, Cameroon, was also helpful in the provision of background information for this report. The authors also wish to thank Crisantos Obama and Maurice Elad of CUREF, Willy Ramon Tomas of the Ministerio de Bosques y Medio Ambiente and Dinga Njingum Franklin of the African Rattan Research Programme, for their diligence and commitment when undertaking fieldwork in extremely difficult circumstances.
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Castroviejo, J., J.B. Juste, R. Castelo & J. Perez de Val. 1994. The Spanish co-operation programme in Equatorial Guinea: a ten year review of research and nature conservation in Bioko. Biodiversity and Conservation. 3: 951-961.
Collel, M., C. Maté & J.E. Fa. 1994. Hunting among Moka Bubis: dynamics of faunal exploitation at village level. Biodiversity and Conservation. 3: 939-950.
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