Forests Of West Africa Research Articles

Bushmeat hunting and management: implications of duiker ecology and interspecific competition

Duikers Cephalophus spp. are an important source of food and income throughout the forest regions of Central and West Africa, and current levels of hunting are probably unsustainable, at least near large settlements. The direct effects of hunting consist of two main aspects: overexploitation of target species, and incidental hunting of non-targeted or rare species because hunting is largely non-selective. There are many methodological and practical problems to a technical approach to overexploitation, and there are increasing calls for alternative measures such as zoning and enforcement of exclusive local resource rights. There is also increasing recognition of the need to ensure that hunting is more selective. This paper reviews current knowledge of duiker ecology and niche separation in order to assess likely indirect effects of these measures on different species. The main factor separating fundamental niches of sympatric species is body size, which limits dietary choice. Additional descriptive factors include anatomical features – particularly the jaw musculature and size of mouth and neck; activity patterns and habitat preferences within closed canopy forest. However, there is wide overlap of diets and broad tolerance of habitat disturbance by most species, and therefore niche overlap and interspecific competition may be high. In the Upper Guinean forest in West Africa, but not in Central Africa, differential use of closed canopy forest and secondary vegetation also appears to be an important factor in niche separation; three pairs of species seem to be separated primarily by this factor. Distributional variations in habitat use suggest that at least in the case of the yellow-backed duiker and the endangered Jentink's duiker, the separation is due to competition rather than to fundamental niche constraints. Selective hunting or zoning will thus have indirect effects on non-targeted species through changes in competitive dominance in different habitats.

Exploring spatial and temporal variation in middle infrared reflectance (at 3.75 @m) measured from the tropical forests of west Africa

In the effort to acquire information about tropical forests across regional scales via remote sensing, recent research notes the potential of the reflected component of middle infrared (MIR) radiation acquired by National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) channel 3 (at 3.75

Rare plants on Mount Oku summit, Cameroon

AbstractThe forests of the Kilum-Ijim area, around Mount Oku in West Cameroon, are the largest remaining patch of montane forest in West Africa, and the highest in altitude. This important habitat harbours endemic species of both animals and plants but is surrounded by a high density of human settlements: c. 300,000 people live within a day's walk of the forest, which covers only 200 sq km. BirdLife International and the Ministry of the Environment and Forestry, Government of Cameroon, are currently operating the Kilum-Ijim Forest Project, with the overall goal of conserving representative areas of the Cameroon montane forest biome in the long-term. The purpose of the project is toensure that the biodiversity, extent and ecological processes of the Kilum-Ijim Forest are maintained and that the forest is used sustainably by the local communities. The existence of a small Sphagnum community and associated wetland plant species was discovered in 1997 on the summit of Mount Oku, at 2900 m. This site is of extremely high conservation importance because several plant species endemic to the Kilum-Ijim area have been recorded there. In addition, it is the highest Sphagnum bog and the source of the highest stream in West Africa.

Rare plants on Mount Oku summit, Cameroon

The forests of the Kilum-Ijim area, around Mount Oku in West Cameroon, are the largest remaining patch of montane forest in West Africa, and the highest in altitude. This important habitat harbours endemic species of both animals and plants but is surrounded by a high density of human settlements: c. 300,000 people live within a day's walk of the forest, which covers only 200 sq km. BirdLife International and the Ministry of the Environment and Forestry, Government of Cameroon, are currently operating the Kilum-Ijim Forest Project, with the overall goal of conserving representative areas of the Cameroon montane forest biome in the long-term. The purpose of the project is toensure that the biodiversity, extent and ecological processes of the Kilum-Ijim Forest are maintained and that the forest is used sustainably by the local communities. The existence of a small Sphagnum community and associated wetland plant species was discovered in 1997 on the summit of Mount Oku, at 2900 m. This site is of extremely high conservation importance because several plant species endemic to the Kilum-Ijim area have been recorded there. In addition, it is the highest Sphagnum bog and the source of the highest stream in West Africa.

Variation in Gender and Flower-Size Dimorphism in the Dioecious Tree Dombeya ciliata, an Endemic to La Réunion Island1

Abstract The genus Dombeya is an important component of tropical forests in west Africa, Madagascar, and the Mascarene islands, but little is known about the reproductive biology of its members. In this study, we quantified gender variation and flower-size variation in three populations of the dioecious tree Dombeya ciliata, an endemic of La Reunion Island (Indian Ocean). Variation among the three populations was observed for three characters. First, the high elevation population had strict males and females, whereas in the two low elevation populations, males were inconstant, with > 50 percent of the males set a small number of fruit. Second, females showed greater seed production at high elevation. Third, flower-size dimorphism was greater at high elevation because male flowers were larger than female flowers.

A New Diospyros (Ebenaceae) from the Udzungwa Mountains, Tanzania

A new species of Diospyros, D. uzungwaensis Frimodt-Moller & Ndangalasi, is described from the Udzungwa Scarp Forest Reserve in Tanzania. The new species appears to belong to sect. Brevituba F. White and to be closest to D. soubreana F. White from the Guineo-Congolian forest of West Africa. It is suggested that this resemblance is yet another example of the affinity between the montane forest flora of the Eastern Arc Mountains in East Africa and the West African forest flora.

Vegetation history of the savanna corridor between the Guinean and the Congolian rain forest during the last 150,000 years

Pollen and spores from a deep-sea core located west of the Niger Delta record an uninterrupted area of lowland rain forest in West Africa from Guinea to Cameroon during the last Interglacial and the early Holocene. During other periods of the last 150 ka, a savanna corridor between the western — Guinean — and the eastern — Congolian — part of the African lowland rain forest existed. This so-called Dahomey Gap had its largest extension during Glacial Stages 6, 4, 3, and 2. Reduced surface salinity in the eastern Gulf of Guinea as recorded by dinoflagellate cysts indicates sufficient precipitation for extensive forest growth during Stages 5 and 1. The large modern extension of dry forest and savanna in West Africa cannot be solely explained by climatic factors. Mangrove expansion in and west of the Niger Delta was largest during the phases of sea-level rise of Stages 5 and 1. During Stages 6, 4, 3, and 2, shelf areas were exposed and the area of the mangrove swamps was minimal.

Forest indigenous peoples: concept, critique and cases

SynopsisThis chapter has two linked objectives. The first is to sketch the process of human occupance of the lowland rain forest zone in West Africa, and illustrate (by means of a case study) the current circumstances of human settlement at the forest margins. The second is to bring the category ‘indigenous peoples’ under review, and to point out some of the pitfalls associated with the use of this term in the context of the West African forest frontier. All parts of the forest zone in West Africa have a long and complex history of occupation and use. In consequence, I shall argue that it is rarely, if ever, realistic to think of forest country as a residuum of empty land not yet passed into human ownership and use, but that it is equally distorting to treat the local groups currently found in possession of the forest edge as sole custodians. Forest resources have over time become part of the fabric of wider community life in West Africa, up to and beyond the national level, and narrow definitions of the category ‘indigenous peoples’ are to be avoided. Rather than search for putative forest indigenes, living in greater harmony with nature than incoming settlers (a usage reflecting Amazonian experience) it would be better, I suggest, to consider the term ‘indigenous peoples’ as covering all groups in West Africa with effective local knowledge of the forest. An eventual aim should be to understand how the experience of forest occupance has passed into the make-up of the institutions and values of civil society throughout the forest zone in West Africa today, regardless of whether or not these groups have a current direct connection to surviving areas of high forest. This is a much broader sociological agenda than conservationists have been prepared to tackle so far, but the threatened forests of West Africa are also complex human landscapes of considerable historical depth, and this human complexity is, in my judgement, no less worthy of understanding and conservation than the envelope of non-human biodiversity from which is has emerged. In fact, the two sets of issues are inextricably intertwined.

Characteristics of dry forest in West Africa and the influence of fire

Abstract. The climate, soil, structure and floristics of dry forests in West Africa are summarised. Data from Ghana show that these forests have two-peak annual rainfall between 850 and 1350 mm, with 6–10 dry months (< 100 mm rain) each year; by relatively nutrient-rich soils developed over a variety of rock types; by short stature (tallest trees 10-40 m) relatively high deciduousness in the upper canopy and evergreenness in the understorey; and by a distinctive flora which changes gradually towards areas of higher rainfall but abruptly at the forest-savanna boundary. Dry forests near the forest-savanna boundary form a distinctive sub-type as a result of occasional encroachment by litter fires which have become more common in the 1980's. Evidence is presented to suggest that many parts of the forest zone in West Africa may have been subject to fires most often in the dry forest types. Past fires are likely to have had a profound influence on the composition of the present forest canopy. Fire mortality is greatest in small trees, whilst drought (without fire) kills more large trees. This thinning process allows rapid recolonisation especially by Marantaceous and Zingiberaceous forbs and by pioneer trees. Seedlings of canopy trees grow beneath these colonising plants. Recurrent fires seriously impede the recovery of burnt forest and are a principal concern for the rehabilitation of dry forests.

Problèmes économiques et écologiques des forêts denses libériennes

Economic and Ecological Problems as Regards Dense Liberian Forests. Liberia, one of the last remaining islands of thick rain forest in West Africa, is seeing its forest disappear with a great rapidity, both because of industrial exploitation (construction lumber, in large part for exportation) as well as to make way for classical shifting agriculture. After an analysis of the causes and consequences of this landclearing on the forest ecosystem, the author proposes a forestry model integrated into the traditional method of exploiting land, which would make it possible to replace the present predatory manner of exploiting a forest with the notion of a renewable natural resource.

ALLOZYME VARIATION IN OLD WORLD RACES OF SORGHUM BICOLOR (POACEAE)

A survey of allozyme variation in cultivated races of sorghum (Sorghum bicolor) was undertaken. Eight plants each of 83 accessions representing the five primary races and five of the intermediate races of sorghum were analyzed for 15 enzyme systems encoded by 27 loci. Low levels of variation were found within accessions, which is typical of self‐pollinating species. Little variation was also found among accessions. Compared with other cereals, S. bicolor is depauperate in allozyme variation. We found an average of 1.81 alleles per locus with a mean expected heterozygosity of 0.008 for the accessions and total panmictic heterozygosity of 0.093. Only 9% of the variation present was found within accessions, while 91% was among accessions. Most of the variation present is attributable to differences in geographic origin of the accessions rather than racial differences. Western and eastern Africa have the highest levels of total heterozygosity (0.108 and 0.088, respectively), while southern Africa has the lowest (0.008). Principal component analysis revealed continuous variation among races and geographic regions with the accessions failing to segregate into discrete racial or geographic clusters.

Conservation and the Development of National Parks in the Humid Tropics of Africa

The diverse humid forests of tropical Africa are on the verge of destruction and the few protected areas are also under threat from illegal land and resource use. The conservation history of these forests dates from about 85 years ago but game and forest reserves have not protected the ecosystems. The humid lowland forests have always been perceived as lacking any potential for tourism and are known to have valuable resources. Thus, few of the humid lowland forests were protected after the major conservation initiatives of 1933 and 1961. Increasing con- cern for the protection of lowland humid forests led to several large national parks being created in the years 1966-74 but few were established in the most threatened forests of West Africa and none in East Africa. The high cost of national park development and the unlikely possibility of tourism has led to biosphere reserves being favoured and it is suggested that these are likely to be more successful than national parks. Specialized forms of tourism are successful in the montane forests however, and the future of national parks in these areas would seem to be assured. The high cost of protecting and managing national parks suggests that unless inter- national financial aid is available, those that have already been established may have an uncertain future. It is proposed that only one large national park is required in each country within the lowland humid forests and that biosphere reserves are more appropriate for other conserved areas in these

Systematics of the Amphi-Atlantic Bambusoid Genus Streptogyna (Poaceae)

Streptogyna is the only herbaceous bamboo genus with an amphi-Atlantic distribution. Streptogyna crinita occurs in tropical Africa, Sri Lanka, and India, and S. americana is found throughout the Neotropics. Although marked differences in habit and in morphology of lodicules and starch grains suggest segregation at the generic level, they are here retained in a single genus because they are quite similar in spikelet morphology and leaf anatomy. Multicellular microhairs are present on the lodicules of S. crinita and mark the first report of microhairs in the genus. Multicellular microhairs are otherwise well developed in the grasses only in the African herbaceous bamboo Guaduella, and they may be a primitive feature in the family as they are common in its putative outgroup, the Joinvilleaceae. Streptogyna shows strong bambusoid affinities in its ligule and leaf anatomy, spikelet structure, caryopsis and embryo morphology, and chromosome number, but differs from the core group of the subfamily in its seedling morphology and lack of epidermal papillae. Autapomorphies in the two species suggest that neither could have been derived directly from the other. The genus Streptogyna was first brought to the attention of Western botanists in the late 18th century, when British and Swedish collectors brought back specimens of rat-catching grass from the forests of West Africa. A gathering from Nigeria by Palisot de Beauvois was used as the basis for Streptogyna in 1812, which he based on the only species known to him, S. crinita. The narrow leaves and many-flowered spikelets of Streptogyna were long taken as indications of pooid (festucoid) affinities. Thus, Bentham (1883), Hackel (1887), and Hubbard (1936) all considered that the proper disposition of this genus from the tropical rainforest lay with this large, temperate-region group. But there were dissenters, and Nees von Esenbeck (1835) and Steudel (1855), for example, suspected the bambusoid affinities of the genus. Streptogyna was briefly revised by Hubbard (1956), who indicated that the group deserved tribal status, but it was not until Tateoka (1958a) and Metcalfe (1960) examined its leaf anatomy that the bambusoid affinities of Streptogyna became clear. Recent workers agree that Streptogyna should be placed in its own tribe in the Bambusoideae (Calderon & Soderstrom, 1980; Clayton & Renvoize, 1986). In a treatment of the herbaceous bamboos of Sri Lanka, Soderstrom et al. (1987) offered a detailed descriptive account of the leafblade anatomy in the two taxa. The present study provides a revision of the genus and attempts to clarify the relationships of the two species by examining characters that have not yet been studied in detail, such as morphology of lodicules, starch grains, and embryos. MATERIALS AND METHODS Specimens of Streptogyna were examined from the following herbaria: AAU, B, BM, BR, CAY, CEPEC, F, G, ISC, K, M, MO, NA, NY, P, PDA, RB, S, US, W, and WIS. For anatomical studies, spikelets, leaves, and embryos (Table 1) were dehydrated in dimethoxypropane, infiltrated with tertiary butanol, embedded in wax, sectioned using a rotary microtome, and stained in chlorazol black E. Lodicules were rehydrated with AerosolOT before examination. Starch grains from caryopses were cut on a freezing microtome and stained with l2KI. Observations of living plants of Streptogyna were made by Soderstrom in Brazil (March 1972, and May 1976) and by Jud1 We are grateful to Alice R. Tangerini for the illustrations, to Stanley Yankowski for the floret sections, to the curators of the herbaria that lent us specimens for study, and to Gerrit Davidse, Lynn G. Clark, and Mary Sangrey. Part of the research leading to this paper was performed while the second author was a predoctoral fellow at the Smithsonian Institution. 2 Department of Botany, Smithsonian Institution, Washington, D.C. 20560, U.S.A. Died on September 1, 1987. 3Department of Botany, Smithsonian Institution, Washington, D.C. -20560, U.S.A. ANN. MISSOURI BOT. GARD. 74: 871-888. 1987. This content downloaded from 157.55.39.179 on Tue, 12 Apr 2016 09:52:13 UTC All use subject to http://about.jstor.org/terms 872 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 74 TABLE 1. Specimens of Streptogyna for which embryos (e), floret bases (using the scanning electron microscope) (f), lodicules (1), and starch grains (s) were examined.

Investigations of the breeding biology of the West-african slender-snouted crocodile Crocodylus cataphractus Cuvier, 1824

AbstractSpecial research on the breeding biology of Crocodylus cataphractus has been done in the Tai National Park, one of the last primary rain forest of West Africa. The seasons for nest construction, incubation period and hatching time were determined. Kind, size and dispersion of nests are described. Information on egg size, clutch size, nest temperature and humidity during incubation is given. Some additional data has been obtained from a breeding-stock of Crocodylus cataphractus in the Abidjan National Zoo.

Soil productivity aspects of agri-silviculture in the West African rain forest zone

The rain forest in West Africa is dominated by ferralitic soils, which are old, highly weathered and low in nutrient reserves and cation exchange capacity. Their fertility is mainly dependent on a delicately balanced cycle of organic matter. Agri-silviculture as practised in this area is held to be a progressive variant of shifting cultivation in that it encourages multiple use of the land and immediate reforestation of the sites after crop harvest while providing the forest owner/cultivator with extra income from sales of poles and timbers. Little attention has been given to the soil, which is inherently poor and further impoverished by export of portions of the meagre nutrient reserve. Drawing on various sources, this paper examines the impact of clearing and burning, cultivation and cropping and the monospecific tree fallows, on the productive potentials of these soils. It is concluded that much has still to be learnt of the restoration of soil fertility under short rotation crops, the loss of nutrients during cropping and the behaviour and response of ferralitic soils to various intensities of cropping and management methods. Some possible topics for research are suggested.

Historical Note on Loa Loa: a Reinterpretation *

Loa loa, also known as the African eye worm, is a common parasite in the central part of West Africa. As Chrysops silacea and C. dimidiata, the only important vectors of loaiasis, are found exclusively in the tropical rain forests of West Africa, the parasite's transmission is confined to this region. References by early writers to the extraction of Loa loa from the eye of a man on the Island of Ormus (today known as Hormuz or Hormus) in the Persian Gulf apparently were based on a misinterpretation of an illustration by de Bry (1595) of the blinding of a royal relative.

Conserving the mangrove forest of the Niger Delta

The Niger Delta mangrove forest is the most extensive of such forests in West Africa. Its nature and extent are examined. The potential bio-economic importance of this unique forest type is discussed and proposals are made for an effective regional conservation programme aimed at managing these resources for a sustained yield.

Ghana's New Forest National Park

In May 1974 Ghana created its first high forest national park. This is a forest reserve in the Bia tributaries area of the Western Region, comprising 118 square miles of some of the highest forest in West Africa, including primary unlogged forest, with an annual rainfall of 57 inches spread over ten to eleven months. The area was chosen partly for the large numbers of elephants and monkeys. The possibility of a forest national park in this region has been under consideration for at least five years; success was achieved after lengthy negotiations under the keen direction of the Chief Game and Wildlife Officer, Dr E. O. A. Asibey.

Exploring Mimetic Diversity in West African Forest Butterflies

In a small area of secondary rain forest in West Africa there is an assemblage of mimetic butterflies based on two colour combinations: dark brown and orange, and black and white. The models are species of unpalatable Danaidae and Acraeidae, the mimics species and polymorphic forms of Nymphalidae, Satyridae, Papilionidae, and Lycaenidae. The models are about five times as abundant as the mimics but difficulties in correlating the frequency of particular mimics with models arise because of difficulties in taking random samples. Males of the principal species of models appear more active than females and are more often encountered, but females of the most important mimic are encountered more often than males. This apparent difference in flight activity between sexes is important as some polymorphic forms of the most abundant mimic are sexlimited. Whether predators encounter the sexes of models and mimics at different frequencies is conjectural. An attempt is made to express mimetic diversity by using an information theory index of species diversity, although no changes in diversity were found during 45 days of continuous sampling. Unexpectedly, mimics seem consistently more diverse than models. Although an entire forest assemblage of mimetic butterflies has been analysed quantitatively, the situation is extremely complex and an understanding of mimetic diversity may only be possible with a detailed knowledge of the ecology of the species encountered.

The Mountain Gorilla and its Habitat in the Birunga Volcanoes

In about 500 b.c. the Carthaginian navigator Hanno brought back the first reports of the existence of gorillas in the forests of West Africa. They were doubtless known also to the early Portuguese and other voyagers along the Guinea coast and in 1590, Battel, who called them “pongos” to distinguish them from the smaller “engeco” or chimpanzee, described them with fair accuracy:—“exactly proportioned like a man, but he is more like a giant in stature for he is very tall and hath a man's face, hollow eyed, with long hair upon his brows…they sleep in the trees and build shelters from the rain. They feed upon fruit that they find in the woods and upon nuts for they eat no kind of flesh.”