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Lama forest is one of the last remnants of the West African forest/savannah mosaic known as the Dahomey Gap. It comprises natural forest and forest plantations and has the protection status of a classified forest. In the present article, we give an overview of an ongoing research partnership project focusing on the conservation of biodiversity in Lama forest. The project is based on the assumption that conser- vation and management strategies must be founded on an understanding of both structural and functional ecological traits. It comprises studies on the biodiversity of arthropods, a group which has received little attention as yet in tropical biodiver- sity assessments, as well as studies on key ecological processes such as the break- down of litter. Emphasis is laid on the relationship and interaction between natural forest and plantations. With respect to ecological as well as biogeographical pecu- liarities, we found evidence of the importance of Lama forest for biodiversity con- servation in Benin. Specifically, our study elucidated the role of anthropogenic fo- rests as buffer zones, migration corridors and surrogate habitats for rare forest ani- mals. Important insight has been gained with regard to the management and con- servation of isolated biodiversity resources in Benin and other African countries.
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Conservation of biodiversity in a relic forest in Benin
an overview
Peter Nagel, Brice Sinsin, and Ralf Peveling
Zusammenfassung
Der Lama-Wald ist einer der letzten Reste des westafrikanischen Wald/Savan
-
nen-Mosaiks, des ‘Dahomey Gap’. Er enthält natürlichen Wald sowie Plantagen
und hat den Schutzstatus einer “Forêt classée”. Im vorliegenden Artikel geben wir
einen Überblick über ein laufendes Gemeinschaftsforschungsprojekt, das sich auf
die Erhaltung der Biodiversität im Lama-Wald konzentriert. Das Projekt basiert
auf der Annahme, dass Erhaltungs- und Managementstrategien auf der Basis des
125
REGIO BASILIENSIS
45/2 2004 S. 125-137
Adresse der Autoren: Prof. Dr. Peter Nagel and Privatdozent Dr. Ralf Peveling, Institut
für Natur-, Landschafts- und Umweltschutz (NLU) / Biogeographie (Institute of Environ
-
mental Sciences, Biogeography), Universität Basel, St. Johanns-Vorstadt 10, CH-4056
Basel. Prof. Dr. Brice Sinsin, Faculté des Sciences Agronomiques, Université d’Abo
-
mey-Calavi, 01 BP 526 Cotonou, Bénin
Abstract
Lama forest is one of the last remnants of the West African forest/savannah mosaic
known as the Dahomey Gap. It comprises natural forest and forest plantations and
has the protection status of a classified forest. In the present article, we give an
overview of an ongoing research partnership project focusing on the conservation
of biodiversity in Lama forest. The project is based on the assumption that conser-
vation and management strategies must be founded on an understanding of both
structural and functional ecological traits. It comprises studies on the biodiversity
of arthropods, a group which has received little attention as yet in tropical biodiver-
sity assessments, as well as studies on key ecological processes such as the break-
down of litter. Emphasis is laid on the relationship and interaction between natural
forest and plantations. With respect to ecological as well as biogeographical pecu-
liarities, we found evidence of the importance of Lama forest for biodiversity con-
servation in Benin. Specifically, our study elucidated the role of anthropogenic fo-
rests as buffer zones, migration corridors and surrogate habitats for rare forest ani
-
mals. Important insight has been gained with regard to the management and con
-
servation of isolated biodiversity resources in Benin and other African countries.
Verständnisses der strukturellen und funktionalen ökologischen Merkmale entwi
-
ckelt werden müssen. Es umfasst Untersuchungen über die Biodiversität der Ar
-
thropoden, einer Tiergruppe, der bis jetzt in tropischen Biodiversitätsuntersuchun
-
gen eher weniger Aufmerksamkeit geschenkt wurde, sowie Untersuchungen über
ökologische Schlüsselprozesse wie den Streuabbau. Hauptgewicht wird auf die Be
-
ziehung und die Interaktion zwischen natürlichem Wald und Plantagen gelegt. In
Bezug auf ökologische wie biogeographische Besonderheiten fanden wirBelegefür
die Bedeutung des Lama-Waldes für die Erhaltung der Biodiversität in Benin. Ins
-
besondere klärte unsere Studie die Rolle der anthropogenen Wälder als Pufferzo
-
nen, Migrationskorridore und Ersatzlebensräume für seltene Waldtiere auf. Wich
-
tige Einblicke hinsichtlich des Managements und der Erhaltung isolierter Biodiver
-
sitätsressourcen in Benin und in anderen afrikanischen Ländern wurden gewon
-
nen.
1 Introduction
The Dahomey Gap is a zone of low rainfall separating the western and eastern part
of the humid Guineo-Congolean evergreen and semi-evergreen forests of West and
West-central Africa, extending along the coast from Takoradi in Ghana to Cotonou
in Benin (L’Hôte & Mahé 1996). The annual precipitation ranges from 900 to
1,500 mm. With respect to the natural vegetation expected under the prevailing cli-
mate, Sayer (1992) postulated a spatial dominance of semi-deciduous forest, inter-
spersed with tracts of denser vegetation such as riverine forest as well as patches of
swamp forest and lowland evergreen forest. This implies that the present savannah
vegetation is of anthropogenic origin. During the humid phase in the Holocene, the
area was presumably covered with evergreen lowland rainforest (cf., Anhuf 1994).
There are several examples of disjunction of plants and animals along the Dahomey
Gap (Knapp 1973, Kingdon 1990, Schiøtz 1999). For some West and West-central
African species, the Dahomey Gap demarcates the eastern and western limit, re
-
spectively, of their present range. This suggests that extant patches of natural forest
in Southern Benin are remnants of the former semi-evergreen lowland forest that
has been largely destroyed by humans. For species distributed in the lowland rainfo
-
rest during the Holocene, these forest remnants are important refuges. Likewise, it
is likely that they serve as stepping stones for species moving between the western
and eastern rainforest belts. Of the forest remnants in southern Benin, Lama forest
represents one of the largest tracts.
With few exceptions (e.g., Sayer 1992), the possible role of Lama forest for
biodiversity conservation has not been acknowledged adequately by the interna
-
tional conservation community (IUCN 1987, 1991). Even though, national institu
-
tions (ONAB 1992) and development agencies (German Development Agency and
German Development Bank), consider Lama forest a priority conservation area, de
-
spite its small size. Preliminary biodiversity inventories were conducted under the
auspices and with the financial aid of these organizations (Emrich et al. 1999).
However, the studies were confined to natural forest in the centre, the so-called
126
Noyau central. While the importance of plantation forests for the conservation of
wildlife and as nuclei for the regeneration of natural forest has been demonstrated
elsewhere in the tropics, confirmation from West Africa is still pending.
The overall goal of the present, ongoing study is the conservation and enhance
-
ment of biodiversity through an improved management of natural and plantation
forests in Lama forest. A central theme in this research is the ecological and
biogeographical role of plantations within an overall conservation strategy for
Southern Benin. To this end, our study focuses on the functional importance of
biodiversity as well as on key ecological processes. The project is conducted within
the scope of a research partnership between the Faculté des Sciences Agrono
-
miques, University of Abomey-Calavi, Benin, and the Institut für Natur-,
Landschafts- und Umweltschutz (NLU) / Biogeographie, University of Basel.
2 Geographical and historical characteristics of the study site
Lama forest is situated at the northern limit of the central part of the Dépression
médiane (between 6°55.8–58.8’N and 2°4.2–10.8’E). The altitude ranges between
40–80 m above sea level, and the average annual rainfall is about 1,200 mm. A large
rainy season from April to July is followed by a short dry season from August to
September, followed by a second, shorter rainy season from October to November
and the large dry season from December to March. During the rainy season, the soil
may become temporarily waterlogged which restricts the agricultural use. The
127
Tab. 1 Recent history of the development of Lama forest (modified after Emrich et al.
1999)
Year Total forest cover (ha)
(except plantations)
Natural forest
cover (ha)
Events
1946 16,250 11,000 Gazetted as a forêt classée;
colonization by autochthonous ethnic
groups (Fon, Aïzo)
mid 1950s Immigration of allochthonous ethnic
groups (Holli and Aïzo from other
parts of Benin)
1960 10,800 Afforestation with exotic timber
species, mainly teak
1972 6,700 Increased immigration of Holli
population
1984 3,800
1985 2,500
1987 4,500 1,900 Full ban on logging of natural forest;
reforestation in the Noyau central;
resettlement of Holli people in two
agro-forestry centres
prevailing soil type is a black cotton soil (vertisol) rich in humus and young clay de
-
posits. The vernacular name is synonymous with Lama, a word of Portuguese
origin meaning mud.
Of the different ethnic groups living at Lama forest, only the Holli tribe immi
-
grants from eastern Benin – are specialized in the cultivation of black cotton soil.
Until their resettlement in 1988, about 1,200 families practiced small-scale shifting
agriculture within the Noyau central. During the preceding five years, the mean an
-
nual deforestation was 400 ha, compared to an overall annual loss of natural forest
of 300 ha between 1946–1988. The former Holli land use system is reflected in the
present structure of the Noyau central which is composed of a mosaic of fallow land
of different age and successional stage, secondary forest and patches of primary
forest.
128
Fig. 1 Outline map of the Lama forest (from Lachat et al. 2004a).
NC = Noyau central T = Teak plantations,
FP = Fuelwood plantations S = Settlements, small-scale agriculture,
IF = Isolated forest fragments
Except for teak forests planted in the early sixties (1963–1965) in the northern
and southern part of the area, teak plantations were established 1985–1996, enclos
-
ing the Noyau central nearly entirely. In the south-western part, fuelwood forests
were planted to satisfy the demand of the local population for firewood, and to re
-
duce the pressure on remnant natural resources. Open canopy forest patches, clear
-
ings and former farmland within the Noyau central are encroached with thickets of
Chromolaena odorata, an alien, invasive species of neotropical origin. Enrichment
plantings with native forest species were established in these open areas in order to
assist and accelerate the regeneration of natural forest.
In view of dramatically diminishing forest coverage and ever increasing defor-
estation rates, a new forest management and protection project was implemented in
1987/88. All settlers were banned from the Noyau central and resettled in neigh-
bouring agro-forestry schemes where they were granted housing and agricultural
land. Moreover, education and health services were provided, and new opportuni-
ties to work in the forest sector were created. The idea was to convert forest users
into forest conservationists. Other measures taken to support local communities
were an improvement of the infrastructure (road network), the establishment of tree
nurseries, and the construction of a saw-mill for the processing of teak and produc
-
tion of parquet floor tiles for the global market. For educational purposes, an eco
-
logical trail was established in the Noyau central in 1995.
3 Implementation of research
To evaluate the role of teak and fuelwood plantations for the protection of the natu
-
ral forest remnants, we focused initially on the following areas of research, (1) the
diversity and composition of arthropod assemblages, in particular detritivorous and
xylophagous species, (2) the niche differentiation of key ecological groups, and (3)
the breakdown of litter and dead wood in relation to forest type.
Access into the forest is possible by a system of parallel trails (layons) running
from East to West at a distance of one kilometre from each other. We selected four
replicate sites in each of nine different forest types. Within the Noyau central, these
129
Tab. 2 Forest cover in Lama forest in 2000 (modified after Emrich et al. 1999)
Area Total surface (ha) Composition
Noyau central 4,800 1,900 ha natural forest
1,200 ha degraded forest of different successional stages
1,400 ha fallow land of different successional stages,
covered mainly with Chromolaena odorata
300 ha teak (Tectona grandis) and grey teak
(Gmelina arborea) plantations
Plantations 9,000 5,600 ha teak plantations
1,400 ha grey teak plantations, partly mixed with teak,
Eucalyptus spp., Acacia sp. and other species
2,400 ha firewood plantations (mainly Senna siamea)
Other 2,400 Agriculture, settlements
comprise (1) semi-deciduous forest (primary forest), (2) seasonally flooded
Cynometra megalophylla lowland forest (primary forest), (3) Anogeissus leiocarpa
dry forest (secondary forest), (4) abandoned settlements (secondary forest) and (5)
perennial Chromolaena odorata thickets. Outside of the Noyau central, we studied
(6) old teak plantations, (7) young teak plantations, (8) fuelwood plantations and (9)
isolated small forest islands.
4 Results
4.1 Geographical Information System
Specht (2002) integrated a geo-ecological catalogue of maps into a Geographical
Information System (GIS). Emphasis was put on the classification of the vegetation,
using multitemporal Landsat 7 data. The exact delimitation of the main vegetation
types is an important basis for both the interpretation of ecological and biodiversity
data as well as for the management of Lama forest. Moreover, possible dispersal
and migration corridors as well as suitable habitats of animals and plants can be de
-
tected.
130
Fig. 2 Dry season aspect of Lama forest (teak plantations, left, and semi-deciduous forest,
right). Photo: T. Lachat
4.2 Biodiversity studies
4.2.1 Vegetation and flora
The natural vegetation of the Lama depression is classified as a dense
semi-deciduous forest. Afzelia africana und Ceiba pentandra are dominant, emer
-
gent species of the uppermost stratum of this forest type, while Diospyros
mespiliformis, Dialium guineense and Mimusops andongensis represent the lower
tree stratum. Disturbed secondary forest is often characterized by Anogeissus
leiocarpa. The vegetation in seasonally waterlogged areas is dominated by large in
-
dividuals of Cynometra megalophylla (Emrich et al. 1999).
The most abundant trees are Dialium guineense, Diospyros mespiliformis,
Albizia zygia, Afzelia africana, Khaya senegalensis and Anogeissus leiocarpa. The
last three species have their main distribution in the drier Sudan zone further to the
North. Two tree species new to Benin were recorded in a recent study. More than 15
species have been listed in the Red List of threatened plants (Emrich et al. 1999).
4.2.2 Arthropod diversity and faunistics
Preliminary evidence was found that the Lama forest and probably other forest rem-
nants of the Dahomey gap are home to endemic Coleoptera and Lepidoptera species
(Goergen 2003). Furthermore, about half of the 83 butterfly species recorded so far
are new to Benin (Fermon & Schulze 1998).
By using a combination of different types of traps (pitfall, Malaise, window and
light traps) we found seven different myrmecophilous ant nest beetles (Carabidae:
Paussini), six of which are stenoecious, typical forest species (Nagel 2003). It is re-
markable that these are extremely rare species. Even though most specimens were
sampled in the Noyau central, we also found some specimens in old teak plantations
and isolated forest fragments.
Lachat et al. (2004a) demonstrated that arthropod diversity was similar among
natural, degraded and secondary forests of the Noyau central, whereas isolated for
-
est fragments differed from all other forest types. Species richness was lowest in
young teak and fuelwood plantations, highest in old teak plantations and forest is
-
lands and intermediate in the different forest types within the Noyau central. A rare
ground beetle, Hoplolenus obesus (Murray) (Carabidae: Oodini), was identified as
an indicator species of old teak plantations, suggesting that anthropogenic forest
ecosystems may have a role to play in biodiversity conservation.
4.2.3 Mammals
Several mammals are frequently encountered in Lama forest, e.g., the common
cusimance (Crossarchus obscurus), Maxwell’s duiker (Cephalophus maxwelli),
red river hog (Potamochoerus porcus) and bushbuck (Tragelaphus scriptus). The
most conspicuous monkeys are the three guenons mona, red-bellied monkey and
vervet monkey (Kassa & Sinsin 2003). It has been suggested that colobus monkeys,
including Colobus vellerosus, have disappeared from Lama forest (Matsuda 1995).
However, new sightings have been recorded recently by our research team.
131
Rare and threatened forest ungulates include the sitatunga (Tragelaphus
spekei), the royal antelope (Neotragus pygmaeus), the black duiker (Cephalophus
niger) und the yellow-backed duiker (C. silvicultor)(Kassa & Sinsin 2003). It is
also possible that the Kintampo rope squirrel (Funisciurus substriatus), an endemic
of the Dahomey Gap, occurs in Lama forest (Refisch 1998).
The flagship species of the Lama forest is the red-bellied monkey
(Cercopithecus erythrogaster erythrogaster). This subspecies is endemic to the Da-
homey Gap and Benin. Its former range in Southern Benin extended from the valley
of the Couffo river to the Nigerian border. Due to hunting and habitat destruction,
surviving populations now seem to be restricted to sacred groves, equally small
swamp forests (e.g., Lokoli forest) and humid forest relics, of which Lama forest is
the largest (Sinsin et al. 2002, Sinsin & Assogbadjo 2002).
There are indications of dispersal movements among these habitat fragments. In
most cases, the red-bellied guenon is associated with mona monkeys. This affords
mutual benefits in terms of predator avoidance and forage location. During the dry
season, the diet of red-bellied guenons consists of immature fruits of the cotton tree,
providing not only food but also water which is a scarce resource during this time of
the year (Nobime & Sinsin 2003). A pilot study on the feasibility of radio telemetry
and habituation techniques for studying the behavioural biology and ecology of
red-bellied monkeys showed that both methods are difficult because of the timidity
and shyness of this species (Altherr 2003).
132
Fig. 3 Bush meat (duiker), confiscated by a forestry officer. Photo: P. Nagel
4.2.4 Birds and reptiles
Fifteen forest bird species in Benin have been observed only in the Lama forest thus
far, including the white-crested hornbill (Tockus albocristatus), the crested Guinea
fowl (Guttera pucherani edouardi), the western bronze-naped pigeon (Columba
iriditorques) and the purple-headed glossy starling (Lamprotornis purpureiceps).
Densities of species such as the bristle-bill (Bleda syndactyla) seem to be at their
lowest limit to maintain viable populations (Waltert 1998).
Among the reptiles, there are interesting species such as Python regius and Py
-
thon sebae (Daouda 1998). A more recent survey found 44 species, including a new
chameleon species and probably a new gecko species (Ullenbruch 2003; Ullen
-
bruch et al. submitted).
4.3 Functional ecological studies
The litterbag technique was used to study the breakdown of leaf litter in different fo
-
rest types (Attignon et al. 2004). Decay rates in semi-deciduous forest were signifi
-
cantly higher than in plantation forests. Moreover, natural leaf litter (afzelia, Afzelia
africana, and cotton tree, Ceiba pentandra) degraded faster than exotic litter (teak,
Tectona grandis, and cassia, Senna siamea). This was related to the activity of lit
-
ter-dwelling invertebrates, suggesting that their role in litter breakdown and nu
-
trient-cycling must be considered in forest management. Several studies have been
initiated to analyse decomposer communities and soil quality in different types of
natural and plantation forests. A synthesis of these ongoing studies, however, is still
133
Fig. 4 The flagship species of Lama forest: red-bellied monkey (Cercopithecus e. erythro
-
gaster). Photo: G. Altherr
pending. Thus far, there are indications that earthworm relative abundance is higher
in natural than in plantation forests (Weibel 2003), whereas the contrary is true for
termites (Attignon et al. submitted a,b).
From 2002–2004, emergence trap studies were conducted to study the associa
-
tion of beetles with dead wood (Cakpo 2003, Lachat et al. 2004b). Again, final re
-
sults cannot be presented as yet. Preliminary evidence suggests that the saproxylic
beetle fauna responds very specifically to the type of dead wood and the degree and
state of its decomposition. From these studies we expect to gain general insight into
the ecological significance of dead wood in these types of tropical forests.
5 Conclusions
All investigations of the composition and distribution of biodiversity resources in
Lama forest conducted so far demonstrated the unique biogeographical and ecolo
-
gical status of the Noyau central. Here, rare Dahomey Gap endemics such as the
red-bellied guenon found one of their last refuges in Benin. Moreover, numerous
rainforest-adapted species occur only in Lama forest, the largest continuous tract of
dense natural forest in southern Benin. For West African forest species such as the
royal antelope, Lama forest represents the easternmost limit of their current range.
These examples underline the importance of this last remnant of dense
semi-deciduous forest and its characteristic fauna for biodiversity conservation in
Benin.
Due to a lack of surface water during the dry season, species in need of water
may have to conduct seasonal movements and migrations into more humid areas
such as the Lokoli swamp forest. These movements can be a risk to maintaining via-
ble populations. Moreover, there is a higher poaching risk for animals moving
through settled land, even though the overall poaching pressure seems to be rela-
tively low. The plantation forests encircling the Noyau central may serve as a Cor
-
don sanitaire, i. e., a protection forest reducing the risk of illegal logging of natural
forest.
The paucity of litter-dwelling invertebrates in plantation forests and the resul
-
tant reduction in litter breakdown clearly suggest that specific forest management
programmes should aim to prevent an impoverishment of decomposer communities
in order to maintain productivity.
The present study focuses on the role of forest plantations for biodiversity con
-
servation in the Dahomey Gap. All evidence collected so far suggests that old teak
plantations in particular (about 40 years old) may provide suitable habitats even for
stenoecious rainforest insects. This seems to be due to the dense and species-rich
undergrowth resembling secondary forest undergrowth. It is noteworthy that even
extremely rare species were found in these plantations, as well as in isolated forest
islands. It follows that conservation programmes should aim to include certain
types of forest plantations as habitats for rare and/or threatened species. Nature con
-
servation and forest production even monocultures are not necessarily mutually
exclusive goals. Rather, both can be combined in an ecologically and economically
viable way.
134
6 Outlook
Few studies have investigated the role of forest plantations as wildlife habitats and
migration corridors. This even holds for mammals and birds, the best studied taxa.
Future studies should therefore aim to identify dispersal routes between Lama forest
and other forest remnants or forest-like habitats. These studies should establish the
scientific basis for the development of a protected area system. The degree of isola
-
tion of fragmented populations should be investigated using molecular genetic
methods, and the analysis be based on metapopulation models. Aspects of the func
-
tional importance of biodiversity in natural forests and plantations are as yet grossly
understudied and should receive more attention in future research in order to predict
possible risks timely.
The Lama forest reserve represents the most important element in the existing
network of remnant forest biotopes in southern Benin. It may even serve as a step
-
ping stone across the Dahomey Gap, even though more field evidence has to be col
-
lected to support this assumption. However, the existing database clearly exempli
-
fies the potential of Lama forest as a national heritage of regional importance. The
data collected so far even suggest the establishment of a Lama Biosphere Reserve.
Scientifically, this claim is founded on the outstanding importance of the Noyau
central, old teak plantations and forest remnants for biodiversity conservation. In
the past twenty years, the local population has been affected tremendously by con-
servation as well as forest production activities of governmental authorities and de-
velopment agencies - sometimes detrimentally, sometimes beneficially. It therefore
certainly must be integrated into a community conservation process inherent to the
designation of biosphere reserves.
Acknowledgements
The Swiss National Science Foundation (SNF) and the Swiss Agency for Develop
-
ment and Cooperation (SDC) are acknowledged for their financial support. We are
also very grateful for the technical support of the Office National du Bois, Cotonou,
Benin, and the International Institute of Tropical Agriculture, Calavi, Benin.
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... The Lama forest reserve is situated in the so-called Dahomey Gap, a savannah corridor that currently separates Upper Guinean (West Africa) and Lower Guinean (western Central Africa) rain forest blocks (Demenou et al. 2018). It is the largest natural forest in southern Benin, and one of the last remnant forests within the Dahomey Gap (Ballouche et al. 2000, Nagel et al. 2004). It harbours several species of major importance in term of conservation. ...
... Preliminary evidence was found that the Lama forest and probably other forest remnants of the Dahomey Gap are home to endemic beetle and butterfly species (Goergen 2003), and several rare species of ground beetles (Carabidae) were observed in the Lama reserve (Nagel 2003). A new chameleon species and probably also a new gecko species (Ullenbruch 2003, Nagel et al. 2004 were also recorded. Finally, more than 15 species of plants of the Lama forest are listed on the Red List of threatened plants (Nagel et al. 2004). ...
... A new chameleon species and probably also a new gecko species (Ullenbruch 2003, Nagel et al. 2004 were also recorded. Finally, more than 15 species of plants of the Lama forest are listed on the Red List of threatened plants (Nagel et al. 2004). All these examples underline the importance of the Lama reserve, the largest remnant of dense semideciduous forest in Benin, and its characteristic fauna for biodiversity conservation in Benin. ...
Article
The Lama forest is the largest natural forest in southern Benin, and one of the last remnant forests within the Dahomey Gap. It harbours several species of major importance in terms of conservation. Small mammals are known to represent more than 80% of the African mammalian species diversity but they have received little attention in Benin. In this article we present the results of the first terrestrial small mammal species inventory (murid rodents and shrews) in the Lama forest. In September and October 2007, we captured 280 small mammals belonging to 12 species, identified by morphological and genetic analysis. We also provide detailed cytogenetic data for six of the 12 captured species. For five of them, we compare our data with previously published karyotypes, and for the sixth one (Hylomyscus pamfi), the karyotype is published here for the first time. Two of the captured species are closed-forest specialists (Praomys misonnei, H. pamfi), and H. pamfi is endemic to the Dahomey Gap region. Our results are congruent with those obtained on other animal groups, and highlight the importance of the Lama forest for the conservation of the country's forest biodiversity.
... Evicted farmers were posted in the management fields now called agroforestry centers, designed as the buffer zone. Income generated from the plantation exploitation is somehow used to secure the core zone which is a natural semi deciduous forest, very important for the wildlife conservation and the regeneration of natural forest (Nagel et al. 2004). In view of the most endemic and endangered animal species, the core zone is the highly suitable habitat, and is strictly protected according to well defined conservation objectives and should be a typical example of natural or minimally disturbed ecosystems (Augustin et al.1996, WU Wang 2004. ...
... Lama forest is located in the Sudano-Guinean climatic zone which characterizes southern Benin (White 1986) (Fig. 1). The specificity of the southern Benin area is its situation in the Dahomey Gap zone (Nagel et al. 2004). The forest benefit from a subequatorial climate with two unequal rainy seasons alternating with two dry seasons. ...
Article
Background The habitat degradation together with fragmentation and illegal hunting represent a major threat for biodiversity conservation in Lama protected areas. Method We used a combination of questionnaire survey with local communities for ranking the hunted mammal species as bushmeat and track surveys in gridded-cell system of 500x500 m ² (n=268) to assess at what extend the management design, the anthropogenic factors and habitat type affect the occupancy model of those mammal species. Results Twenty mammal species have been predominantly reported by the local inhabitants to consume bushmeat species and 5 of them have been identified as the most preferable as hunted game mammals. The selection of the preferred habitat among the swampy forest, the dense forest, the tree plantations and cropland for the prioritized game species varies between species but looks similar when grouping in different orders. Some bushmeat species were found to select the more secure habitat (natural forest); suggesting the zoning system in the Lama forest can passively protect those species. However, some species such as T. swinderianus although highly hunted showed preference to anthropogenic habitat, avoiding the well secured core zone in Lama Forest. Conclusion Our findings highlighted the importance of the zoning system with different management objectives in the habitat occupancy model of the highly hunted wildlife species.
... The Lama forest reserve is a semi-deciduous forest located in southern Benin (Nagel et al., 2004) between 6 • 55 and 7 • 00 North latitude and 2 • 04 and 2 • 12 East longitude (See Fig. 1). It covers 16,250 ha including 4,777 ha of natural forest entirely protected since 1986 and known as the 'Noyau Central' (Goussanou et al., 2017). ...
Article
The soil seed bank (SSB) in forests is a key indicator of their resilience after disturbances. Despite the growing interest in describing patterns of SSB and understanding potential processes underpinning those patterns, we still know little about SSB patterns and drivers in semi-deciduous tropical forests. Using the regeneration emergence method, we assessed the patterns of SSB (i) across four vegetation types with variable intensity of past human disturbances: typical dense forest - degraded dense forest - young preforest fallow - old preforest fallow, and (ii) in relationships to soil depth (0–5 cm, 5–10 cm, 10–15 cm, 15–20 cm) in a protected tropical semi-deciduous dense forest in Benin, West-Africa. The standing vegetation (adults and regeneration) data and soil samples were collected using a systematic sampling of 60 plots of 10 m × 10 m in the four vegetation types. Herbaceous plants dominated (67% − 78%) the SSB. From the SSB, five tree species emerged: Ceiba pentandra (L.) Gaertn., Dialium guineense Willd., Ficus sur Forssk., Leucaena leucocephala (Lam.) De Wit, and Lonchocarpus sericeus (Poir.) Kunth. Regarding tree species, the total densities of germinated seeds (seeds.m−2) were higher in typical dense forest (28.00 ± 7.22) and young preforest fallow (16.67 ± 7.07) than in old preforest fallow (10.00 ± 6.75) and degraded dense forest (8.89 ± 3.81). When only tree species were considered, the SSB was more diverse and dense in typical dense forest than in other vegetation types suggesting negative effect of past human disturbances on SSB. The similarity of the species composition between the SSB and the surrounding vegetation was low (Jaccard's similarity index ranged from 0 to 17.64%, indicating that the majority of tree species in the surrounding vegetation were absent in the SSB. This study highlighted a need of planting effort of native tree species to restore degraded areas.
... Sayer (1992) postulated that in the Dahomey Gap the expected natural vegetation under the current climate would consist of semi-deciduous forest interspersed with tracts of denser vegetation types such as riverine forest as well as patches of swamp forest and lowland evergreen forest. Nagel et al. (2004) and Tossou et al. (2008) claimed that this implies that the present-day savannah vegetation was humans-induced, while Salzmann and Hoelzmann (2005) demonstrated that, before its establishment, the Dahomey Gap was occupied by evergreen forests with typical Guineo-Congolian forest trees species. This past climatic phase plays an important role in explaining presentday tree species distributions (Linder et al., 2005;Waltari et al., 2007). ...
Article
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African bush mango trees (Irvingiaceae) are priority food trees in West and Central Africa. There are bitter-and sweet-fruited species, which are difficult to distinguish based on morphological characters. This has led to a debate about their correct taxonomic status. Furthermore, it is unclear whether they are native to the Dahomey Gap, the dry and hot area, separating the two West African forest blocks. This study evaluates the ecological differences between bitter-and sweet-fruited species in tropical Africa, and the nature (wild vs. cultivated) of the occurrences in the Dahomey Gap, in order to discuss the current taxonomical opinions. Irvingia gabonensis and I. wombolu occurrence data were combined with climate and soil data in MaxEnt to produce environmental niche models. Environmental niche identity tests were carried out in ENM-Tools. Wild sweet-fruited trees were predicted in the Guinean-Congolian phytogeographical region, while the predicted occurrence of bitter-fruited trees extended to the Guineo-Congolia/Sudania and Lake Victoria transition zones. The related niche difference is significant, supporting the taxonomical opinion that bitter-and sweet-fruited species are two different taxa. We also conclude that bitter-fruited trees occur naturally in the Volta forests (Dahomey Gap). Moreover, our results support that I. gabonensis is not native to the Dahomey Gap. In historical times, they were probably introduced from Nigeria.
... The study was conducted in the Republic of Benin (West Africa) which belongs to the so-called Dahomey gap ecological zone, where D. microcarpum naturally occurs (Agbo et al. 2018). The Dahomey gap is this abnormally drier and hotter ecological zone inside the Upper Guinean forest, where savannah ecosystems reach the seacoast, mostly on Benin and Togo (Nagel et al. 2003). Phytodistricts where the species occurs within the Sudanian and Guineo-Sudanian zones, were visited: Atacora chain, Mekrou-Pendjari, North Borgou, South Borgou, Bassila and Zou (Table 1). ...
Article
Full-text available
Detarium microcarpum (Caesalpiniaceae) is a priority, multipurpose, and indigenous food tree species in West Africa. However, data related to its efficient conservation and sustainable use, through changing ecological environments, are still lacking. Thus, species occurrence records were combined with climatic and soil data in Maximum Entropy (Maxent), a species distribution modelling algorithm, to evaluate the impacts of future environmental conditions (under CNRM-CM5 and HadGEM2-ES) on the species’ potential distribution in Benin. Results indicated that the species’ present potential distribution range was mainly found in the Sudanian and Sudano-Guinean ecological regions. Some extensions and retractions of the present-day distribution (lowly, moderately and highly suitable habitats) were noted under future climates based on the two scenarios. Introduction of D. microcarpum in suitable habitats are required for its efficient conservation in West Africa.
... In West Africa, the Dahomey Gap covers southern Benin and Togo (up to about 8°N latitude; Fig. 1). It is a mosaic of small deciduous forest patches (protected by national forest administrations or local communities), vast savannahs, plantations of exotic tree species (e.g., Tectona grandis, Lamiaceae; Terminalia species, Combretaceae; Gmelina arborea, Verbenaceae), and cultivated fields (Nagel et al. 2004). No consensus exists regarding the causes (natural or anthropogenic) of the gap, established since the Late Holocene between the Lower and Upper Guinean forest blocks. ...
Article
Full-text available
Cultivation of priority plant species ensures their sustainable management. African bush mango trees (Irvingia gabonensis and I. wombolu) are the most exploited Irvingiaceae species. Experts disagree on the status of these very similar taxa, as taste remains the only character by which they can be distinguished in the field. We combined occurrences and environment data in ecological niche models to assess suitable areas for the two species. Irvingia gabonensis presented a wider occurrence area due to cultivation across contrasting ecological areas. Irvingia wombolu does not appear to be cultivated and only occurred in southwestern Togo. These differences in range is likely determined by phenological limitations of I. wombolu, reinforced by differences in local management systems, thus confirming the failure of market development to impact useful plant species’ conservation significantly. Highly suitable areas for I. wombolu were in the Volta Forest, where I. gabonensis saw low suitability, while out of this inverse situation was observed, as regard environmental suitability. These differences are significant, implying different ecological adaptation. However, anthropogenic influences, related to domestication history, are also important. Therefore, updated genetic investigations and field trials in contrasting ecological areas are required for understanding the origin of differences between these two forms.
... Many of these forests are severely degraded in terms of structure and species diversity, which calls for rehabilitation measures. Apart from the detailed study of Adomou (2005), only shortterm mapping of the flora and rapid surveys through interviews have been conducted (Adjanohoun et al. 1989, Sokpon and Agbo 1999, Nagel et al. 2004, Juhé-Beaulaton 2008, Kokou et al. 2008, Hèdégbètan 2011, Agbani 2012, CERF Bénin 2013. ...
Article
Full-text available
In a twenty-year effort at Drabo, southern Benin, small remnant forests, young fallow and agricultural fields were linked and rehabilitated to develop a 14 ha forest reserve. Forest regrowth was encouraged by managing the natural growth of the local fallow vegetation and by bringing in seeds and other propagules from forest islands of Benin. The succession to shade-tolerant woody forest species of Guineo-Congolian origin at the expense of extra-regional herbs, the co-existence of species with slightly different requirements, and the fate of exotic trees in this natural forest are described. A quantitative assessment of a homogeneous lot indicated 397 trees per ha, with stem diameters >10 cm, 43.7% of them below 20 cm, and a rich undergrowth of 72600 smaller plants per ha, proof of active rejuvenation. Only 4.2% of all plants resulted from the 1041 introduction events, i.e., species per date, mostly of the 253 plant species that were new to Drabo. A total of 635 species were recorded, but 50 did not survive and four are yet to be identified. In June 2016, the total of 581 known living species included 224 trees. Among all plants, 244 hailed from the Guineo-Congolian zone with 17 of Upper Guinean and four of Lower Guinean origin, 113 from the three savannah zones, and 224 were of extra-regional origin. Overall, 72.8% of all woody plants, such as many climbers, all shrubs and trees, were of forest and savanna origin (GC, SG, SZ and S), whereas 70.4% of all herbs came from other regions (At, PAL and Pt). Only 7.0% of all species from the GC zone were in decline; but the further away the plants originated from, the larger the decline in numbers and vigour, up to 64.6% among plants of pan-tropical origin. Particularly pan-tropical herbs became ever rarer, with 80.0% of them declining and confined to the few open spaces along paths. In 2017 the forest harboured 52 threatened species, with threat categories EW, CR, EN or VU on the Red List of Benin, out of 73 IUCN-listed species that could possibly survive in Drabo. Some of these species occur in only one or two other locations in Benin. The biodiversity richness of the rehabilitated forests of Drabo now rivals that of natural rainforest remnants of the region. As the surrounding landscape becomes ever more impoverished because of the high human population and its ever increasing impact, the maintenance of such managed islands of biodiversity is critical. By establishing rare local species from other locations we can compensate for direct human destruction and long-term stochastic loss of species in this highly fragmented landscape where natural seed dispersal is difficult. Benin, sacred forest, threatened plants, IUCN Red List, forest regeneration, Guineo-Congolese semi-deciduous forest
... The study area was the Lama forest reserve, a semideciduous forest ecosystem located in southern Benin (Nagel et al. 2004) between 6°55 0 and 7°00 0 Latitude North and 2°04 0 and 2°12 0 Longitude East. The map of the location of the study area was presented in Goussanou et al. (2016). ...
Article
Full-text available
Allometric equations developed for the Lama forest, located in southern Benin, West Africa, were applied to estimate carbon stocks of three vegetation types: undisturbed forest, degraded forest, and fallow. Carbon stock of the undisturbed forest was 2.7 times higher than that in the degraded forest and 3.4 times higher than that in fallow. The structure of the forest suggests that the individual species were generally concentrated in lower diameter classes. Carbon stock was positively correlated to basal area and negatively related to tree density, suggesting that trees in higher diameter classes contributed significantly to the total carbon stock. The study demonstrated that large trees constitute an important component to include in the sampling approach to achieve accurate carbon quantification in forestry. Historical emissions from deforestation that converted more than 30% of the Lama forest into cropland between the years 1946 and 1987 amounted to 260,563.17 tons of carbon per year (t CO2/year) for the biomass pool only. The study explained the application of biomass models and ground truth data to estimate reference carbon stock of forests.
Article
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Illegal hunting of wildlife is one of the major issues in tropical ecosystems, especially when it occurs in highly degraded habitats with forest cover fragmentation. In this study, we assessed the impact of bushmeat hunting in a large forest patch (the Lama Natural Forest; LNF) and 11 nearby forest islands, using Traditional Ecological Knowledge from 240 interviewees across 16 villages. Thirty‐five species belonging to nine orders of mammals, birds and reptiles were mentioned by local communities. Rodentia were significantly more observed in the forest islands, whereas medium‐sized mammals belonging to Carnivora, Primates, Artiodactyla, Pholidota and Hyracoida were found predominantly in LNF. Approximately 57% of the species were reported to be rare in the forest islands, whereas c. 77% were listed as abundant in LNF, confirming the role of LNF as a refuge for forest species targeted by the bushmeat trade. Generalised linear models indicated that species sighting frequencies were positively correlated with perimeters of forest patches. We found hunting pressure to be greater in forest islands in the vicinity of LNF than those further away. Our results suggest that long‐term conservation of wildlife in southern Benin may require a ‘mainland‐islands’ approach including both LNF and its surrounding forest islands. La chasse illégale de la faune sauvage est l'un des problèmes majeurs des écosystèmes tropicaux, surtout lorsqu'elle se produit dans des habitats fortement dégradés avec une fragmentation du couvert forestier. Dans cette étude, nous avons évalué l'impact de la chasse de viande de brousse sur une grande aire forestière (la Forêt Naturelle de la Lama; FNL) entourée de 11 îlots forestiers, en utilisant les connaissances écologiques traditionnelles de 240 personnes interrogées dans 16 villages. Trente‐cinq (35) espèces appartenant à neuf ordres de mammifères, d'oiseaux et de reptiles ont été mentionnées par les communautés locales. Les rongeurs ont été significativement plus observés dans les îlots forestiers, tandis que les mammifères de taille moyenne appartenant à l’ordre des Carnivores, Primates, Artiodactyles, Pholidotes et Hyracoïdes ont été trouvés principalement dans la FNL. Environ 57% des espèces ont été signalées comme étant rares dans les îlots forestiers, alors que 77% d'entre elles ont été répertoriées comme étant abondantes dans la FNL, ce qui confirme le rôle de cette dernière en tant que refuge pour les espèces forestières ciblées par le commerce de viande de brousse. L’analyse des modèles linéaires généralisés a indiqué que les fréquences d'observation des espèces étaient positivement corrélées avec les périmètres des forêt/îlots forestiers étudiés. Nous avons constaté que la pression de chasse était plus forte dans les îlots forestiers situés à proximité de la FNL que dans ceux qui en sont plus éloignés. Nos résultats suggèrent que la conservation à long terme de la faune sauvage dans le sud du Bénin pourrait nécessiter une approche "continent‐îles" intégrant à la fois la FNL et les îlots forestiers environnants.
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The overall objective of the research was to generate soil organic carbon (SOC) reference data for the benefit of the REDD+ initiatives. In this study, SOC was derived from direct measurements of organic matter (OM) content in soil. Six hundred and seventy five soil samples were collected to 30 cm depth in black cotton soil and across three vegetation types including undisturbed forest, degraded forest and fallow in a Guinean forest zone in West Africa. The samples were analysed for bulk densities and for soil OM using loss-on-ignition method. Between 12% and 21% OM per soil mass was found at all layers, 0–10, 10–20 and 20–30 cm, suggesting that black cotton soil was organic soil. OM and C contents and SOC were higher in the upper soil layer and decreased with depth. The highest values of these soil factors were detected in undisturbed forest. The low variation of these soil factors within each vegetation type and their fairly homogeneous spatial distribution across vegetation types confirmed that soils in degraded forest and fallow reached equilibrium, considering undisturbed forest as reference. The lowest bulk density (BD) was found in the top 10 cm layer of the soil depth. There were no significant differences between the mean values of BD observed at the same horizon across vegetation types.
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Arthropod assemblages were examined in Lama forest reserve, a protected area situated in the Dahomey gap, southern Benin, composed of plantations, degraded forest and remnants of natural forest. The objectives were to compare assemblages in relation to forest type and use, to elucidate the value of forest plantations for biodiversity conservation and to identify indicator species for specific forest habitats. Arthropods were collected over an 11-month period, using standardized sets of traps (pitfall, emergence, Malaise and flight intercept traps). Nine different habitats were studied, including natural and degraded forest, forest plantations (Tectona grandis and Senna siamea) of different age, and isolated forest fragments. Our analysis focused on detritivorous and xylophagous arthropods but also included ground beetles and heteropterans, totalling 393 species. We found no differences in species richness among natural and degraded forest habitats in the centre of the reserve (Noyau central). Outside of the Noyau central, species richness was highest in old teak plantations and isolated forest fragments and lowest in young teak and fuelwood plantations. Detrended correspondence analysis (DCA) separated three main groups: (1) natural forest, (2) degraded forest and young plantations, and (3) old plantations and isolated forest fragments. Multiple regression of DCA scores of the first two axes on environmental variables identified one natural and three disturbance-related predictors of arthropod assemblages in Lama forest: soil type (texture), canopy height, naturalness (proportion of Guineo-Congolian plant species) and understorey vegetation cover. We identified 15 indicator species for six different forest habitats. The highest numbers were found in abandoned settlements and old teak plantations. β-diversity was similar among the three DCA ordination groups (degraded forest excluded). Values for β-diversity were relatively high, suggesting that all major forest habitats contribute significantly to regional species pools and should therefore be protected. To enhance arthropod diversity, we propose that management practices in Lama forest should aim to encourage the development of species-rich understorey vegetation of the Guineo-Congolian phytogeographical region.
Article
Responses of termite assemblages to the conversion of semi-deciduous forest into teak plantations were studied in the Lama Forest Reserve in Benin, West Africa. Four belt transect surveys were run in each of the two forest types, adopting a modified termite diversity assessment protocol. Termite assemblages were remarkably species-poor in both forest types, with only 19 species encountered altogether. The low species richness was due to the rarity of soil-feeders of the soil/humus interface and the absence of true soil-feeders in the compact vertisol soil. Species richness was significantly higher in semi-deciduous forest than in teak plantations, but termite encounters were significantly lower. Termite assemblage and feeding group structure differed significantly among forest types. Wood-feeders were recorded only in semi-deciduous forest. In contrast, fungus-growers were more species-rich and about four times more abundant in teak plantations, mainly due to one Ancistrotermes species. The humification score, which depicts the position of termite assemblages along a gradient of increasing humification of their food substrate, was significantly higher in teak plantations, due to the absence of wood-feeders and the preponderance of fungus-growers. Combined principal components and multiple regression analysis identified two significant predictors of termite assemblages, soil water content and leaf litter biomass. The abundance of fungus-growers in teak plantations seemed to be mainly related to the high leaf litter biomass. Indirect evidence also suggests that lower predation pressure by ants on termites in teak plantations may have contributed to the abundance of termites.
Article
The Lama forest reserve in southern Benin, West Africa, comprises timber and fuelwood plantations as well as some of the country’s last vestiges of semi-deciduous lowland forest. The reserve is intended to protect the fauna and flora and to promote the sustainable use of tree plantations. An important aspect in its management is the preservation of soil quality, which in turn is related to key ecosystem processes such as decomposition. In the present study, we examined the breakdown of leaf litter from two indigenous species Afzelia africana (A. africana) and Ceiba pentandra (C. pentandra), and two exotic tree species Tectona grandis (T. grandis) and Senna siamea (S. siamea), using the litterbag technique (1920 litterbags altogether). We also studied the relationship between litter breakdown and the relative abundance (frequency of occurrence) of litter-dwelling invertebrates. The study was conducted over a 140-day period, focusing on four different forest types: semi-deciduous natural forest, young teak, old teak and fuelwood (mainly S. siamea) plantations. Both main factors, litter species and forest type, had a significant effect on litter breakdown. The residual litter weight was lowest in A. africana, intermediate in S. siamea and C. pentandra and highest in T. grandis. Differences were significant for all but one pairwise comparison (A. africana versus S. siamea). With regard to forest type, the breakdown was highest in natural forest, followed by young teak, old teak and firewood plantations. Except for teak plantations (young versus old teak), all comparisons were significant. We also found a significant litter × forest interaction, indicating dissimilar changes in litter breakdown across forest types. With the exception of teak, decay rate coefficients (k) were higher than in most tropical forests, ranging from k = 1.3 (T. grandis in firewood plantations) to k = 4.7 (A. africana in natural forest). The frequency of occurrence of invertebrates differed among leaf litters and forests, while there was no significant litter × forest interaction. Higher frequencies were observed in indigenous than in exotic litter. Likewise, litterbags in natural forest attracted more invertebrates than those in forest plantations. We found a significant inverse linear relationship between invertebrate frequency and residual litter weight, indicating that the breakdown of litter was strongly related to the activity of invertebrates. Our study concludes that management practices should aim to enhance decomposer communities to safeguard the productivity and sustainable use of Lama forest.