Author: LEA

18Sep

Conservation biology of Tamarindus indica (Fabaceae) in Benin

LEA

PhD Dissertation:

FANDOHAN Adandé Belarmain (2011). Conservation biology of Tamarindus indica (Fabaceae) in Benin, West Africa. University of Abomey-Calavi. Benin. ? pages.

Promotor: Prof. Brice SINSIN.

 

Abstract: My thesis in a contribution to domestication of tamarind (Tamarindus indica L.) using an interdisciplinary approach. My results has highlighted that tamarin dis an agroforestry fruit tree with a high socioeconomic value. In Benin its wild populations are confined to semi-arid zones whilst some planted individuals are observed in the subhumid area of the country. This species is better preserved in protected areas than in agroforestry parcs where its sustainable use requires assisted regeration. Ten traditional morphotypes have been described by locals and confirmed using quantitatif descriptors of fruits. Abiotic factors have a relative influence on its productivity, fruits traits and phenology. The analysis of the spatial patterns of tamarind tree in situ have suggested to consider 40 m radius patches using a 10 m x 10 m planting grid for establishing tamarind stands. Despite common association of termite mounds with tamarind trees in the wild, these insect structures are not necessary for them to grow.

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)


17Sep

Analysis of the impact of teak distribution (Tectona grandis L.f.) on landscape structure in the Atlantic Department (Southern Benin)

LEA

PhD Dissertation:

TOYI Sêwanoudé Scholastique Mireille (2012). Analysis of the impact of teak distribution (Tectona grandis L.f.) on landscape structure in the Atlantic Department (Southern Benin). University of  Abomey-Calavi, Benin. 216 pages.

 

Thesis supervisors: Prof. Dr. Ir. Brice SINSIN (University of Abomey-Calavi, Benin) &  Prof. Dr. Ir. Jan BOGAERT (University of Liege – Gembloux Agro Bio Tech, Belgium).

ABSTRACT: The landscape of Atlantic Department (southern Benin) is facing deep changes due to increasing anthropogenic pressures (extension of agricultural lands, inappropriate agricultural practices and wood extraction, urbanization and population growth) which has not been really quantified so far. Reforestation mainly based on teak (Tectona grandis L.f.), was undertaken in order to reduce this alarming degradation and to secure wood supplies. The monitoring and the quantification of land cover dynamics in the study area are therefore necessary to draw attention on these landscapes highly dependent on traditional extensive farming. The impact of teak (Tectona grandis L.f.) diffusion on landscape structure in southern Benin was analyzed. The study was intended to quantify the spatiotemporal land cover dynamic using diachronic data (geo data maps from 1972, 1986 and 2005) and landscape ecology techniques; and to assess the reforestation efforts in order to determine the roles played by these tree plantations in landscape components improvement. These consisted in, determining the dynamics and the evolution trend of land cover classes as well as the main spatial transformation processes in these classes; elaborating the suitable bases to inventory teak plantations through the analysis of their spectral signatures, analyzing the edge effects on teak timber productivity and finally, determining the role of teak plantations in the connectivity of landscape elements. Remote sensing and GIS (Geographic Information System) permitted to assess the spatiotemporal dynamic of the studied landscape between 1972 and 2005, based on multi-dates and multi-sources data. Landsat Multi-Spectral Scanner (MSS), Landsat Thematic Mapper (TM) and Landsat

Enhanced Thematic Mapper plus (ETM+) images were processed to generate land cover maps. Transition matrixes and the “decision tree algorithm” were used to capture differently the observed dynamics while modelling techniques based on the first order Markov chain permitted to simulate future trends up to 2025. The spectral signature of teak plantations was approached through the classification of the 2010 SPOT 5 image combined with field works. The productivity and ecological functions of teak plantation were essentially studied based on indexes specific to landscape ecology. It emerged that the landscape of Atlantic Department was submitted to a progressive degradation from 1972 to 2005 with a drastic regression of natural woody areas (forests and various types of savannas) as confirmed by the spatial processes of fragmentation and suppression, while agricultural lands significantly increased because of creation and enlargement processes. The area of tree plantations as well as settlements (especially in the south of the study area) increased noticeably as shown by land cover maps. In the short and medium terms, the trends observed could not be reversed regarding wooded areas. Agricultural areas will increase and tree plantations would not be able to compensate the losses of natural vegetation and the related services. The mapping of teak plantations through their spectral signatures analysis enabled to locate the regions of wide concentration of teak, but the accurate area could not be estimated. The edge effect, far from being a factor of wood downgrading, had a positive impact on the productivity of private teak plantations which are targeted to the production of poles (timber with diameter ranging from 5 to 15 cm) and by-products to satisfy consumers’ needs in service wood and firewood. The ecological function of teak plantations was explored by considering corridor network scenarios to reduce the patch isolation of surviving forests in the landscape and to protect the specific species of these forests. These network scenarios must be tested for an optimum use of teak plantations. The sustainable management of teak plantations, natural vegetation and the related biodiversity must take into account a suitable institutional framework, the respect of landscape ecological functions, an appropriate technical base, the improvement of the livelihoods and income of the rural population. The integration of these various factors in designing the management plans of municipalities in the Atlantic Department must be the top priority of decision makers. This thesis built on a fast and cheap methodology for investigating and monitoring landscape which is well suited to the context of developing countries such as Benin.

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)


16Sep

Phytosociology, ecology, production and carrying capacity of rangelands surrounding Monts Kouffé (Benin)

LEA

PhD Dissertation: 

Marcel R. B. HOUINATO (2001). Phytosociology, ecology, production and carrying capacity of rangelands surrounding Monts Kouffé (Benin). Free University of Brussels, Belgium. 264 pages.

Promotor: Prof. Jean LEJOLY.

Abstract: Between 1996 and 1998, floristical surveys were carried out. Some 159 phytosociological relevés were done, according to Braun-Blanquet approach. They resulted in 954 herbarium specimens corresponding to 584 species. Detrended correspondence analysis of these relevés leads to nine well defined new plant associations which were classified into two classes. Hyparrhenietea class Schmitz 1963 of the sudano-zambezian savannah communities enclose the Schizachyrio-Sorghastretum bipennati ass. nov. of swamp on clayey soils, the Loudetiopsio-Hyparrhenietum rufae ass. nov. of swamp on sandy soils, the Elymandro- Monocymbietum ceresiiformi ass. nov. of fallows wetland, the Gardenio-Siphonochiletum ethiopici ass. nov. of savannas in evolution and the Gardenio-Pteleopsietum suberosae ass. nov. of fallows on plateaus. The Erythrophleetea africani Schmitz 1963, class of woodlands enclose the Andropogono-Isoberlinetum dokae ass. nov. of young woodlands, the Uapaco-Isoberlinietum dokae ass. nov. of more evoluted woodlands, the Aframomo-Anogeissetum leiocarpi ass. nov. and the Pouterio-Anogeissetum leiocarp iass. nov. of dry forests. The maximum phytomass significanty varied among associations during the same vegetation cycle. The highest maximum phytomass was obtained in swamp savannah and the lowest in woodlands. Considering life forms that composed the associations, phanerophytes (36%) and Therophytes have highest proportion. About phytogeography, Sudanian species represent 16.1 % of the total flora spectrum of Mounts Kouffé region. Two species of the three endemic genuses to sudanian region were collected, i.e. Vitellaria paradoxa and Pseudocedrela kotschyi. The species present in both Sudanian and Zambesian regions made up 13.5% of the phytogeographical spectrum and those of the Guineo-Congolian region accounted for 11.3% of the spectrum. They mostly belonged to gallery forests and dry forests because of the position of this region which is located in the most southern part of the Sudanian region close to the regional transition zone of Guinea-Congolian/Sudanian. The other species widespread in several regions within continental African phytochoria represented 33% of the spectrum. Widely distributed species represented 25.2% of the spectrum. The impact of bush fire on the dynamic of vegetation in Bassila forest was studied. The results show reforestation in the plot protected from bush fire and decrease of forest species in the plot affected by late fire. In the plot affected by early fire, most species present at the beginning of the study had a normal development. Late fire allowed apparition of new species of therophyte (36%) and decrease of phanerophyte species. Phanerophytes have the same values (45 %) in the plots protected from bush fire and those affected by early fire.

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)


16Sep

Livre – Autres Livres

LEA

Atlas de la Biodiversité de l’Afrique de l’Ouest. Biodiversity Atlas of West Africa, volume 1 : Bénin

Brice Sinsin & Dorothea Kampmann (eds), 2010 Cotonou & Frankfurt/MainISBN 978-3-9813933-0-9, hardcover ISBN 978-3-9813933-3-0, paperback

Atlas de la Biodiversité de l’Afrique de l’Ouest. Biodiversity Atlas of West Africa, volume 1 : Bénin

Brice Sinsin & Dorothea Kampmann (eds), 2010 Cotonou & Frankfurt/MainISBN 978-3-9813933-0-9, hardcover ISBN 978-3-9813933-3-0, paperback

Protection de la Nature en Afrique de l’Ouest : Une Liste Rouge pour le Bénin. Nature Conservation in West Africa : Red List for Benin.

Neuenschwander, P., Sinsin, B. & Goergen, G. (eds). 2011. International Institute of Tropical Agriculture, Ibadan, Nigeria. 365 pages. ISBN : 978 978 49796 9 6

Règles de classement et taux d’erreur en analyse discriminante.

Glèlè Kakaï R. (2010). Bibliothèque Nationale. Edition Européenne Universitaire, Allemagne, 237p. ISBN:978-613-1-53762-2

 

Biodiversité des Légumes Feuilles Traditionnels consommés au Bénin.

Dansi A. et al. (2008). ISBN : 978-99919-68-63, Bibliothèque Nationale, Bénin

Conditions d’application des méthodes statistiques paramétriques.

Glèlè Kakaï R., Sodjinou E., Fonton H. N. (2006). Bibliothèque Nationale, Bénin, 102p. ISBN:-10-99919-61-15-1 or 13-97899919-61-15-6

L’analyse discriminante décisionnelle : aspects théoriques et applications sur ordinateur.

Glele Kakai R., Palm R., Kokode G. (2005). Notes tech. Biom, ISBN : 99919-51-90-3, Bibliothèque Nationale, Bénin, 64p.

Techniques statistiques univariées et multivariées : applications sur ordinateurs.

Glele Kakai R., Kokode G. (2004). Notes tech. Biom, ISBN : 99919-902-6-7, Bibliothèque Nationale, Bénin, 67p.

Manuel d’aviculture à l’usage des pisciculteurs pour les élevages associés (cas des poules pondeuses).

Zoffoun G. A., d’Almeida J., Demoulin F. (2003). PAMR-MONO, 141p.

L’élevage des porcs associé à la pisciculture.

Zoffoun G. A., d’Almeida J., Demoulin F. (2003). 1ère Partie, Aspects Généraux. PAMR-MONO, 141p.

L’élevage des porcs associé à la pisciculture.

Zoffoun G. A., d’Almeida J., Demoulin F. (2003). 2ème Partie, Engraissement et Reproduction, PAMR-MONO, 150p.

Règles de classement et taux d’erreur en analyse discriminante

Glèlè Kakaï R. (2010). Bibliothèque Nationale. Edition Européenne Universitaire, Allemagne, 237p. ISBN:978-613-1-53762-2

 

Biodiversité des Légumes Feuilles Traditionnels consommés au Bénin.

Dansi A. et al. (2008). ISBN : 978-99919-68-63, Bibliothèque Nationale, Bénin


16Sep

Book – Protection de la Nature en Afrique de l’Ouest : Une Liste Rouge pour le Bénin. Nature Conservation in West Africa : Red List for Benin.

LEA

Protection de la Nature en Afrique de l’Ouest : Une Liste Rouge pour le Bénin. Nature Conservation in West Africa : Red List for Benin.

Neuenschwander, P., Sinsin, B. & Goergen, G. (eds). 2011. International Institute of Tropical Agriculture, Ibadan, Nigeria. 365 pages. ISBN : 978 978 49796 9 6.  International Institute of Tropical Agriculture, Ibadan, Nigeria. 365 pages. ISBN : 978 978 49796 9 6

Les informations nécessaires pour la mise en œuvre de la protection de la nature au Bénin sont rares et dispersés. Ce volume pour la première fois prents informations en 33 chapitres couvrant les plantes rares et menacées, les insectes, les poissons, les antilopes, les grands chats, etc. L’état ou plus de 550 espèces est évaluée en fonction des critères de l’UICN, et leurs noms locaux, de courtes descriptions, des écologies et les distributions sont donnés. Le livre est d’un intérêt pour ceux qui travaillent dans la conservation de la nature dans les écoles, les Ong, les touristes à des agences gouvernementales.


14Sep

Managment and modeling of the transhumance pasture dynamic in a climatic variabilies context in North-East of Benin

LEA

PhD Dissertation:

Paolo Lesse (2016). Managment and modeling of the transhumance pasture dynamic  in a climatic variabilies context in North-East of Benin. University of Abomey-Calavi, Laboratoire d’Ecologie Appliquée. 299p

Promotor: Prof. Marcel R. B. HOUINATO.

 

ABSTRACT: Transhumance is a herding system which occupies an important place in the West Africa region and in Benin particularly. This study has been carried out in the North-East Region of Benin which is herders’ predilection area. The general objective of this work is to contribute to a sustainable management of transhumance corridors in the North-East of Benin. The natural corridors have been characterized using linear plots measurements, the method of short cut for the biomass quantification and the phytosociological plots. The herding system has been studied using the system approach. The sensitivity matrix has been used to better assess the vulnerability level of the herders to hydroclimatic variabilities. The future evolution of rainy and thermometric extremes in the basin has been analyzed thanks to the data of the regional climatic model REMO. The Land Change Modeler (LCM) of IDRISI Selva has been used to predict the land occupation state in 2050. The current study allowed bringing out the system constraints. They were feeding, climatic variabilities, legislation, conflict and availability of pastoral infrastructures problems. In total, 162 infrastructures capable of serving as water sources in the study area have been identified but not functional or in a bad state characterized by the inexistence of access trails toward the water points, the presence of abundant vegetables floating on the surface of the waters and the functioning problems of the management mechanisms put in place. Four (04) types of pastures having productivity varying between 3.46 and 5.7 tons of Dry Matter/ha have been identified. The Prosopis africana and Eragrostis atrovirens pasture and the Piliostigma honningii and Stylosanthes fruticosa pasture presented respectively the highest nutritive value for the grass and the legume plants. Twelve (12) transhumance corridors oriented toward the water points and the protected areas have been repertoried and mapped in the study area. About the demographic parameters, the mean annual rate growth is of 1.068 ± 0.05 while the mean production rate is low (0.155 ± 0.02). By the 2050 horizon a contrasted evolution of the rains regimes have been predicted with a mean heating of 1°C. Under the transition probabilities basis, the predictive modeling realized on the land occupation by the horizon 2050 predicted that the tree and shrub savannas will occupy 49.89 % of the total area of the natural North East grassland of Benin Republic. The variability observed is explained by the delay in the beginning of the rains, the bad repartition of the early arrest of the rains, the violent winds. The vulnerability analysis allowed noticing that herding is the most vulnerable and that herders fear more droughts and floods than the rains decreases.

 

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)

14Sep

Poverty Dynamics and Agricultural Practices for Environment Conservation in African Rural Area: the Case of Adja plateau in Southern Benin

LEA

PhD Dissertation:

Emile N. HOUNGBO (2008). Poverty Dynamics and Agricultural Practices for Environment Conservation in African Rural Area: the Case of Adja plateau in Southern Benin. University of Abomey-Calavi, Benin, 309 pages.

Director: Prof. Brice A. SINSIN.

Abstract: The influence of increase in land pressure on agricultural production and the environment is disputed. On one hand the pessimists, mainly represented by MALTHUS (1798), think that land pressure is associated to negative effects on agricultural production and leads to famine, environmental degradation and rural exodus. On the other hand the optimists, mainly represented by BOSERUP (1970), think that land pressure is an essential factor for technological change and agricultural intensification. In fact, although in general the demographic and food evolution in Africa presents a Malthusian trend, like the cases of Yatenga in Burkina Faso, Serer district in Senegal and Adja plateau in Benin Republic, it was even though observed some Boserupian evolutions like the cases of Bamileke district in Cameroon and the district of Machakos in Kenya. One wonders if it’s still possible to presage in Africa a generalised optimistic evolution of BOSERUP (1970) and in which conditions.

This thesis, from a temporal analysis of 122 households on the Adja plateau in the southern Benin, is developing a theoretical intermediary position between MALTHUS theory and that of BOSERUP. It’s demonstrating that in land pressure situation, the farmers’ welfare state was a determinant of improving agricultural practices development and agricultural productivity improvement. Land pressure does not induce ipso facto technological change and agricultural development.

 Theoretical relationship between land pressure and agricultural productivity

 The MALTHUS spectrum and the optimistic vision of BOSERUP represent the extreme situations induced by a higher chronic poverty rate in the first case and a lower chronic poverty rate in the second case. In order that the farmers can develop sustainable agriculture in land pressure situation, it’s necessary to alleviate or eradicate chronic poverty among them by facilitating a truly profitable agriculture.

https://tel.archives-ouvertes.fr/tel-00680042/document

 

 

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)

14Sep

Analysis of the mode and utilization technologies of palm oil mill wastes and its application for the production of three tropical vegetables (Lycopersicon esculentum, Amaranthus cruentus, Corchorus olitorius) in Southern Benin

LEA

PhD Dissertation: 

KOURA Windékpè Tatiana (2015). Analysis of the mode and utilization technologies of palm oil mill wastes and its application for the production of three tropical vegetables (Lycopersicon esculentum, Amaranthus cruentus, Corchorus olitorius) in Southern Benin. Department of Natural Resources Management, Faculty of Agronomic Sciences, University of Abomey Calavi, Benin republic, 252p.

Promotor: Prof. Dr. Ir. SINSIN A. Brice.

Abstract: Owing to the revitalization of the palm oil manufacturing sector in South Benin, some mills are confronted to the problems of waste management although there are many ways these wastes can be reused. To assess how these wastes are managed, waste production systems were determined by numerical classification and considering palm oil production factors and quantities of waste, and characterized through aprincipal component analysis. A semi-structured survey was conducted among 335 oil mills. Four extraction methods (EM) had been identified: traditional (T), improved (I), modern (M) and semi industialized (SI). The amount of wastes generated by each category of oil mill was determined by evaluating that generated by 7 T, 4 I, 4 M and 9 SI oil mills randomly chosen. The study identified four classes of waste production systems: small, medium, large and very large. They produced on average per year 12.4 ± 22 t; 31.3 ± 52.8 t; 132.7 ± 59.1 t and 800.7 ± 418.1t empty fruit bunches; 5.6 ± 10.3 t; 13.6 ± 23.1 t; 135.2 t ± 95.2and 637 ±312.6 t fibers and 15.1 ± 23.7 t; 40.9 ± 28 t; 233.4 ± 172.1 t and 572.6 ± 90.3 t sludge respectively. They were discriminated by the nature and size of plantations, the financial capacity of the mills owners to hirelaborers and the quantities of waste produced. The use of all the amount of generated bunches and fibers did not depend on the quantity produced. Thus, the relationship between the EM improvement andthese wastes management was analyzed. The effect of the EM, the type of waste and their interaction on the calculated indices (user’s percentage, the commercial value, the Rejection Rate, the Importance Value, and the Use Value) were assessed using the log linearly analysis. The fidelity level of each use for each mill was calculated. However, within categories, all mills considered each use at the same level. Whatever theEM, the surplus waste was eliminated either by discharging into the environment or selling. These options were more observed when the EM was improved. Ethnobotanical indexes were used to evaluate the importance and value of palm oil mill wastes in palm oil production areas. A Two Principal Component Analyses was performed to characterize palm oil mill waste uses in link with the production areas. The results showed that the sludge has no importance for mills ‘owners. Oil mills that used the whole amount of bunch and fibers produced were those for which the waste was important for a unique use. The palm oil mill waste contributed more to environmental pollution in Plateau, Couffo and Mono. In order to find immediate solutions to mills facing waste management problems, we proposed solid wastes co-composting and the use of this compost in vegetables production. The analysis of the sustainability of agricultural practices implemented by producers in relation to their knowledge revealed that the use of empty fruits, bunches and fibers depends on producers’ knowledge. These wastes were spread by local application (76.5%) or mulching (33.3%) in plantations or indirectly after composting. Composting is made either by heaping, in combination with pigs breeding or in pits. Composting is a process unknown by 67.5% of mills’ owners. The difference between those who know about it and use it, and those who know about it but do not use it is based on their knowledge of composting advantages. The physico-chemical composition of these wastes were assessed using an ion chromatograph and revealed that these wastes are relatively rich in nutrients except in phosphorus. The co composting of empty fruits bunches and fibers was tested in eighteen bins installed in a split plot design not repeated. Composting method (No shelters (NS) andunder shelter (US)) was the main factor and the type of manure (No manure (NM), poultry manure (PM) and cow dung (CD)) was the secondary factor. As results, the decomposition of wastes and the compost quality obtained varied significantly (p <0.05) with the method of composting and type of manure used. The lowest ratio Carbon/Nitrogen (C/N) 18.38 was obtained in compost where FV were used and made without shelter. The FV had improved the quality of composts in phosphorus content. However, the analysis of leachate revealed high loss of total nitrogen (88.3 ± 12.6mg / l to 146.2 ± 16.4mg / l), potassium (37.2 ± 0.8 to 53.3 ± 1.2 mg / l) and phosphorus (107.9 ± 23.7 to 187.4 ± 65.8mg / L). The high levels of chloride (1301.3 ± 195.8 to 1656.7 ± 147.8 mg / l), biological oxygen demand (3499 ± 425.8 to 6370.7 ±1031.7) shows the need to avoid making the compost heap directly on the ground. The effectiveness of composts was tested with the production of Lycopersicon esculentum, Amaranthus hybridus and Corchorusolitorius were evaluated through a split-split plot design with composting method as the main factor and the types of manure and composts application rates (0t / ha 5t / ha to 10t / ha and 20t / ha) as secondaryfactors. There were 24 treatments and 4 replicates per vegetable. The PM-based compost produced with no shelter (NS) increased amaranth growth and yield (19,2t / ha) compared to others composts. However,in the case of Corchorus olitorius, composts made from waste and CD performed US was recommended. The application of composts increased the yield of Corchorus olitorius and Lycopersicon esculentum from10t / ha.

Keywords: Palm oil mill wastes, waste management, extraction method, type of manure, composting method, vegetables production

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)


14Sep

Ecology of plant communities in the Biosphere Reserve of Pendjari, BENIN (West Africa)

LEA

PhD Dissertation: 

Eméline P.S. ASSEDE (2014). Ecology of plant communities in the Biosphere Reserve of Pendjari, BENIN (West Africa). University of Abomey-Calavi, Bénin. 364 p.

Supervisor : Prof Brice Sinsin.

Abstract: My PhD study provided information and knowledge on the plant communities, plant ecology and population structure of the Biosphere Reserve of Pendjari (BRP). An overview of the flora of the BRP showed that plant species composition of 802 plant species distributed among 428 genera and 102 families, was typical of Sudanian savanna. The recorded endemic species of Benin demonstrated the importance of the reserve for plant conservation.

Two major floristic groups correlated with the gradient of soil moisture (drylands versus wetlands).  Clear differences were shown between wetland plant communities while there were similarities between some dryland plant communities. Soil was one of the determining factors of the distribution of plant associations, and soil moisture was one of the main ecological parameters determining the establishment of species and plant association development. Ferruginous soils, poor in organic matter, are dominated on plateau with clay soils. In wetlands, the soils were a deep silty-clay without gravel.

The analysis of regeneration potential of different vegetation types identified in the BRP reflected the overall structure of the tree layer. Fire as main management tool of the BRP and seed viability explained the dominance of Fabaceae (28.8%) in the regeneration. However topography was a key element in plant establishment. Contrary to the floodplains where soils are poorly drained and poorly aerated, preventing good root penetration, plant regeneration was more important on the border of streams and the hill slopes.

The complexity of the regeneration strategy of plant species and factors controlling that, can also be read through the population structure, as the recruitment of seedlings determines the composition of future populations. A comparative analysis of the population structure of Pseudocedrela kotschyi and Terminalia macroptera in pure and mixed stands indicated that young T. macroptera individuals were predominant in both pure and mixed stands. Trees showed weak density and a random pattern. P. kotschyi young individuals were found to be predominant irrespective of standregime. Trees had a higher density and stronger clumped pattern in pure stands as compared to mixed stands.

The diversity and functional attributes of plants were changed but also recovered after disturbance.The secondary succession in the BRP exhibited a clear floristic pattern with a progressive establishment of the woody vegetation. The first state exhibited the highest species richness with 18.6% of all species exclusive to this state and was characterised by the proliferation of widespread species that disappeared by the third state. About 22% of the 233 species recorded were recorded throughout the fallow cycle. The transition from the first to the second state was characterised by the disappearance of 77% of the total species richness.  Maintenance of a certain state of disturbance is important to maintain total plant diversity in the reserve. Organic matter and the species richness were the best discriminating variables of the succession states. The colonisation of the herb layer by Andropogon gayanus var. bisquamulatus(typical Sudanian species) in the third state can be seen as an indication of a substantial return of soil fertility.

Keys words : Ecology, Vegetation structure, soil properties, Pendjari reserve, Benin

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)


14Sep

Ecological gap analysis: Assessing the ecological effectiveness of Pendjari Biosphere Reserve in biodiversity conservation in Bénin (West Africa)

LEA

PhD Dissertation: 

Dehouegnon Thierry HOUEHANOU (2012). Ecological gap analysis: Assessing the ecological effectiveness of Pendjari Biosphere Reserve in biodiversity conservation in Benin (West Africa). UNIVERSITE OF ABOMEY-CALAVI, Benin. 179 pages.

PhD Promotor: Prof.  Dr. Ir. Brice A. SINSIN.

SUMMARY: Since protected areas are often assumed to be the best way to conserve biodiversity, the current study assessed the ecological effectiveness of Pendjari Biophere Reserve in conservation of some biodiversity targets. In chapter 1 (general introduction) the study’s background, objectives, some theoretical concepts and the thesis structure are presented while Chapter 2 presents the study area Chapter 3 estimates the local preferred uses of three trees target species. Traditional ecological knowledge linked to these species was documented. These species are Afzelia africana Sm., Pterocarpus erinaceus Poir. and Khaya senegalensis (Desv.) A. Juss, multipurpose trees widely used in Africa, yet endangered in their natural environments. The preferred used has been analyzed by means of a cultural importance index. Local ecological knowledge on their conservation was investigated among local people living around Pendjari Biosphere Reserve in Bénin. In total, 160 repondents belonging to four ethnic groups (Gourmantche, Waama, Berba and Peulh) were interviewed in twelve villages. Male and female respondents, aged between 20 and 90 years, were randomly selected in each ethnic group. For each species, a cultural importance index was calculated combining frequency and importance of use. This index allowed us to identify differences in use intensity within and among ethnic groups. Traditional ecological knowledge was tested as a dependent variable of ethnicity. The results showed that A. africana was widely used as medicine, fodder and crafting by most communities, whereas P. erinaceus was the preferred source of fodder for all local people. K. senegalensis was mostly used as medicine and fuel wood by most communities, except by the Peulh who prefer using it as fodder. The use of these trees as source of fuel wood was mostly reported by women while their religious uses were reported by old men from the Gourmantche ethnicity. Medicinal and fodder use of A. africana, fodder use of P. erinaceus and medicinal use of K. senegalensis had the highest overall cultural importance index value. Knowledge relating to local extinction of the target species and their sustainable use varied among socio-cultural groups. These findings have been used so as to propose conservation strategies towards an effective conservation of these tree species. Chapter 4 assesses the effectiveness of the Pendjari Biosphere Reserve to conserve habitat species composition and population structure of A. Africana Sm., P. erinaceus Poir. and K. senegalensis (Desv.) A. Juss. The following two research questions were addressed: (i) do protected habitats of these tree species differ from those unprotected in species composition? (ii) Have population structures (expressed by density and size class distribution) of these tree species been positively affected by this protected area? One hundred and twenty (120) plots were randomly sampled in the protected and surrounding unprotected habitats by inventorying plant species. For the three target species, we measured adult and juvenile, densities and recorded size classes. According to floristic composition four habitat groups were identified in relation to human disturbance, vegetation type, official protection status and moisture. There were protected savannas, unprotected savannas, old fallows and gallery forests. The estimated adult densities of A. africana were similar between protected (13.64 tree/ha) and unprotected savanna (17.44 tree/ha) while for P. erinaceus the adult density was significantly higher in protected (11.74 tree/ha) than in unprotected savanna (4.76 tree/ha). Estimated adult density of K. senegalensis was also significantly higher in protected gallery forest (40.00 tree/ha) than in unprotected one (28.89 tree/ha). Juvenile densities of A. africana, K. senegalensis and P. erinaceus were higher in protected habitats than in unprotected ones but the difference was not significant. In all cases, protected area was effective for maintaining large individuals. Skewness coefficient indicated that populations of investigated trees were declining in their protected habitats. However, the case of A. africana and K. senegalensispopulations seemed to be knocker in the protected area. Our results would suggest PBR to be effective in protecting savanna habitats against fragmentation and it should be required to define and applymanagement strategies for conserving effectively A. africana and K. senegalensis in the protected area in future. In Chapter 5 we assessed the effectiveness of Pendjari Biosphere Reserve to conserve woody species composition, diversity and structure of savannas, the most widespread vegetation type of the study area. The results showed that the two savanna types yielded a total of 58 species representing 44 genera and 23 families with Combretaceae, Mimosoideae, Caesalpinioideae and Rubiaceae as the most abundant families in descending order. However, some species had high Importance Value Index (IVI) in unprotected savanna while others showed the same scheme in protected savanna. Higher values of species richness, Shannon–Wiener’s diversity and Margalef’s index were found in the protected savannas comparatively to the unprotected ones at tree layer level. The number of individuals and the densities were significantly higher in protected savannas compared to the unprotected ones at shrub layer level. As far as the basal area is concerned significant higher values were found in the protected savanna compared to the unprotected one at the two layer levels. From these findings it can be concluded that the effectiveness of PBR to conserve savannas structure and woody diversity depends on the woody layer. However, woody species composition change in relation to savanna conservation status may be also evident according to interrelation specific-use-species. Chapter 6 studied stand structure and spatial distribution of A. africana as helpful to understand its primary seed dispersal mode. Spatial distribution pattern of adult trees and juveniles of the species, spatial relationship between those two life-stages and stand structure were investigated in A. africana dominated savannas. Results showed that A. africana displayed in the Reserve random distribution at large distance scales considering all individuals. However, aggregated distribution was observed at small scale (up to 9 m) in some areas. The adults displayed in all areas a random distribution either at large and small distance scales. The spatial distribution pattern of juveniles followed the same trend of distribution of all pooled individuals and revealed a clumping distribution up to 9 m and random distribution at large scales. The spatial relationship between adults and juveniles did not reveal a positive association between them either at small or large scale. Stand structure also showed a variation for some structural parameters: tree-density and basal area in the Reserve. We suggest that seed dispersal mode by gravity should be the primary seed dispersal mode of A. africana. Chapter 7 assessed the potential effectiveness of PBR on preventing mistletoes proliferation on Shea tree individuals. Shea tree infestation by mistletoes was assessed in two contrasted habitats: land use areas (fields and fallows) and protected area (PBR). Results showed that about 80% of Shea trees are infested in land use area while only 27.3% of trees in PBR were infested. Overall, heavily infested Shea trees had significantly larger trunks and heights, mainly in land use areas. The land use area was shown to be correlated with high and very high Shea tree infestation degrees while the other infestation degrees (very weak, weak and moderate) were correlate with both areas. Therefore Shea trees growing in protected areas are better protected against mistletoe plant parasites than those on cultivated land. Chapter 8 deals with Variation of mistletoes impact on Shea tree fruit yield in contrasting habitats and implication for its conservation. Forty-one (41) weakly and 41 heavily infected Shea tree individuals with similar size were selected in protected area and in its adjacent parklands. Shea tree traits such as diameter at breast height, canopy diameter, tree height, canopy height, number of fruit yielded, number of parasite stumps and a built impact index ratio were assessed on each Shea tree individual. Two-way ANOVA showed that mistletoe did not impact fruit yield significantly either in parklands or in protected area. Hierarchical cluster analysis tended to group all pooled Shea trees based on habitats. One-way ANOVA and canonical discriminant analysis performed on quantitative traits revealed that Shea tree groups were significantly discriminated and many infested Shea tree individuals in parklands were characterized with highest value of number of infestation stumps (n) and impact index ratio. Considering correlation between traits, a variation was found between the two contrasted habitats. Findings have been used to implement some Shea tree conservation plans. Chapter 9 deals with the general discussion on effectiveness of the PBR to conserve biodiversity. The PBR was found to be relatively effective in targets biodiversity conservation. However, management actions need to be addressed to improve biodiversity conservation in this Biosphere Reserve.

  • Vue globale des 5 bâtiments du Laboratoire d’Ecologie Appliquée (LEA). (Photo credit: Dr Akomian Fortuné Azihou / LEA, Octobre 2018)