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Plant diversity in a Central African rain forest: Implications for biodiversity conservation in Cameroon Africa (Hamilton, 1982; White, 1983; Maley, 1987, 1989 & 1990; Sosef, 1994 & 1996). In such refugia, the unique combination of climatic and geological histories, contemporary ecological factors, and inherent biological properties of taxa and their combinations, may have contributed to survival and/or speciation (Barbault & Sastrapradja, 1995; Hawksworth & Kalin-Arroyo, 1995). Furthermore, the Campo- Ma’an area forms part of the Guineo-Congolian Regional Centre of Endemism (White, 1983). All families endemic to this biogeographic region are found in the area (White, 1983). They include Hoplestigmataceae, Huaceae, Lepidobotryaceae, Medusandraceae, Pandaceae, Pentadiplandraceae and Scytopetalaceae. Moreover, 82% of endemic genera cited by White (1983) also occur in the area. They are Afrobrunnichia, Amphimas, Anthonotha, Aneulophus, Antrocaryon, Aphanocalyx, Aubrevillea, Aucoumea, Anopyxis, Baillonella, Brenania, Buchholzia, Calpocalyx, Coelocaryon, Coula, Crotonogyne, Cylicodiscus, Desbordesia, Didelotia, Discoglypremna, Distemonanthus, Duboscia, Endodesmia, Erismadelphus, Grossera, Heckeldora, Hylodendron, Hymenostegia, Hypodaphnis, Gilbertiodendron, Gossweilerodendron, Loesenera, Monopetalanthus (now synonym of Bikinia), Ophiobotrys, Pachyelasma, Poga, Tessmannia, Tetraberlinia, Turraeanthus and Tieghemella. Forest richness and biodiversity hotspots The study has demonstrated that the submontane forest, the lowland evergreen forest rich in Caesalpinioideae with Calpocalyx heitzii and Sacoglottis gabonensis, and the lowland evergreen forest rich in Caesalpinioideae are richer in species of high conservation priorities compared to the other forest types. This is confirmed by the high average GHI scores recorded in these forest types (Figure 5.3). More than 57% of the plots recorded have a high average GHI score (GHI > 150). However, the coastal forest on sandy shorelines and forest rich in Aucoumea klaineana had lower GHI scores than others. There was a strong significant negative correlation between the average GHI scores and the average PI scores recorded in the various vegetation types. Most of the National Park and the coastal forests around Massif des Mamelles and Mont d’Eléphant was characterised by a high conservation value with small patches of forest with very high conservation value located in the submontane forest on hilltops, in Dipikar Island, on Massif des Mamelles, and Mont d’Elephant. More often, these forests were virtually undisturbed or less than 25% disturbed (Figure 5.5). This implies that the Massif des Mamelles and the Mont d’Elephant areas represent other biodiversity hotspots, located outside of the Park (Figure 5.7). In the contrary, the forests around Campo, agro-industrial plantations, logging concessions, near villages and along the roads had a low conservation value with low GHI scores, high PI scores and high levels of disturbance. This confirmed that disturbed forests are rich in pioneer species but poor in plant species with high conservation priority. It is worth reiterating that a considerable portion of the Campo-Ma’an area has been selectively logged at least twice during the past 30 years. Although logging damages were moderate and had low effect on the total forest biodiversity, it has created forest gaps that allowed the development of many pioneer species. This might have contributed to the high average PI scores registered in the coastal forest types. Threatened species During the selection of species of high conservation priority, taxa were chosen on a global rather than a Cameroonian or a Campo-Ma’an perspective of conservation 100
Biodiversity hotspots and conservation priorities in Central African rain forests importance, since we feel that the plants of Campo-Ma’an are of global importance. In total, 141 species of high conservation priority and 92 threatened species listed in the IUCN (2002) and WCMC (1998) were identified for the Campo-Ma’an area (Tables 5.6 & 5.7). Of the 29 strict endemic species that are only known from the Campo- Ma’an area, 17 were not recorded in the National Park illustrating the need for conservation activities outside the park. Their distribution patterns showed a high concentration of species around Campo, Lobe, Massif des Mamelles, Mont d’Eléphant and Zingui and a very poor representation in the Ma’an area (Figure 5.2). Although these 17 strict endemics are not immediately threatened with extinction, the most threatened are probably those occurring in the coastal zone and in areas located at the vicinity of large agro-industrial plantations, since these areas are heavily exploited. As shown in Figure 5.5, their habitats are fragmented and degraded because these areas are surrounded by farms and heavily disturbed forests. Taking into consideration the fact that extinct species are taxa that are no longer known to exist in the world after repeated search in their type localities (WCMC, 1998; IUCN, 2002), we can not yet talk about extinction because no attempt has been made to search for these species. Furthermore, only 67% of the total amount of specimens collected were identified at species level. However, with the ongoing speed of forest degradation noticed in the coastal area, 8 of these strict endemics (Beilschmiedia dinklagei, Deinbollia macroura, Ledermanniella batangensis, Psychotria aemulans, P. batangana, P. dimorphophylla, P. oligocarpa, and Strychnos canthioides) that are only known from the coastal zone can be categorised as endangered species. While the 9 others that are located inland around Efoulan, Fenda, Massif des Mamelles, Mont d’Eléphant and Zingui can be categorised as vulnerable. They are Afrotrewia kamerunica, Bulbophyllum alinae, Begonia montis-elephantis, Calvoa stenophylla, Dorstenia dorstenioides, Guaduella mildbraedii, Hypolytrum sp. nov., Scaphopetalum acuminatum and S. brunneo-purpureum. Some of them so far are only known from type specimens or from a few collections made in the type locality before the 60s. Others such as Afrotrewia kamerunica, Begonia montiselephantis and Hypolytrum sp. nov. have a restricted range with a small and restricted population. Furthermore, habitat fragmentation may convert a previously more continuous population structure to a metapopulation structure, with local populations becoming so small that they may have a substantial risk of extinction (Hawksworth & Kalin-Arroyo, 1995). Implications for biodiversity conservation The Campo-Ma’an National Park The National Park is the core conservation area of the Campo-Ma’an Technical Operational Unit. It is surrounded by areas under several land uses that have varying ecological impact on the park and the surrounding forests. The park is of high conservation priority with about 72% of the 2297 species of vascular plants, ferns and fern allies recorded so far in the Campo-Ma’an area. More than 70% of the total endemic species recorded were also found in the National Park, and most of the forest types with high GHI scores, low PI scores and high conservation priority species were also found in the park (Figures 5.3 & 5.7). The most important one is the endemic lowland evergreen forest rich in Caesalpinioideae with Calpocalyx heitzii and Sacoglottis gabonensis, a vegetation type that only occurs in the Campo area 101
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Chapter 1 GENERAL INTRODUCTION Gild
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Plant diversity in a Central Africa
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Chapter 2 CENTRAL AFRICAN TROPICAL
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-2.0 Plant diversity in a Central A
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Chapter 3 DIVERSITY PATTERNS IN THE
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SUMMARY Summary The fragile ecosyst
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Summary suggest that the Campo-Ma
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RESUME Résumé La biodiversité de
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Résumé nombreux auteurs qui argum
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SAMENVATTING Gildas Peguy Tchouto M
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