Romain Glèlè Kakaï

Women’s Traditional Knowledge, Use Value, and the Contribution of Tamarind (Tamarindus indica L.) to Rural Households’ Cash Income in Benin

Women’s Traditional Knowledge, Use Value, and the Contribution of Tamarind (Tamarindus indicaL.) to Rural Households’ Cash Income in Benin. This study examined differences in knowledge, use values, and contribution of tamarind (Tamarindus indica) to women’s cash income during the dry season, focusing on seven tribal groups in Benin. Data were gathered using semistructured individual interviews and monitoring, and were analyzed using quantitative ethnobotanical methods. Principal component analysis was applied to describe the use value and use forms of tamarind according to different tribes. Tamarind was found to play an important role in local communities’ livelihoods. Overall, 26 different uses were mentioned for tamarind products. Most commonly, the fruit (pulp) was used to make beverages, as a laxative and purgative, and it seems to be the only plant part sold commercially. Bark was frequently used as a medicine to treat wounds, and leaves were used to make porridge and as an antibiotic. Medicinal, cultural, and material use categories were correlated best with the Fulani, whereas commerce was most correlated with Gourma tribes (PCA analysis). There were significant differences for tamarind utilization among the tribal groups, with overall ethnobotanical use values (EUVT) ranging from 10 to 14, and contribution to cash income ranging from 8.8% to 56.4%. In view of its domestication potential, it is crucial that traditional tribal knowledge of tamarind be preserved and integrated into management policies. Further development and research needs for utilization and conservation are improvement of commercialization, organization of market channels, and extent of genetic diversity within and among populations.ResumenSavoir endogène des femmes, valeur d’usage et contribution du tamarinier au revenu des ménages ruraux au Bénin. Cette étude a mis en évidence les différences entre groupes tribales sur les connaissances, les valeurs d’usage, et la contribution du tamarinier au revenu monétaire des femmes pendant la saison sèche au Bénin. Les données ont été collectées grâce à des entretiens individuels semi-structurés et analysées au moyen de méthodes ethnobotanique quantitatives. L’analyse en composante principale a été appliquée pour décrire la valeur d’usage et les formes d’utilisation du tamarinier en fonction des différentes tribus. Le tamarinier joue un rôle important dans les activités génératrices de revenues pour les communautés locales. Au total 26 différentes utilisations ont été mentionnées pour les produits issus du tamarinier. Généralement, la pulpe du fruit est utilisée pour faire des boissons, comme un laxatif et un purgatif et semble être la seule partie commercialisée de la plante. L’écorce est fréquemment utilisée en médecine traditionnelle pour traiter les blessures profondes alors que les feuilles sont utilisées pour la préparation de bouillis et comme un antibiotique. L’espèce a plus une valeur médicinale, culturelle et artisanale pour les Fulani alors qu’elle a une plus grande valeur commerciale pour les tribus Gourma (analyse ACP). Des différences significatives ont été observées entre les tribus sur l’usage du tamarinier, avec des valeurs d’usage ethnobotanique total comprises entre 10 et 14 et des contributions au revenu monétaire variant de 8.8% à 56.4%. Compte tenu de son potentiel à la domestication, il est crucial que les connaissances traditionnelles sur le tamarinier soit préservées et intégrées dans les politiques de gestion. L’amélioration de commercialisation, l’organisation de circuits de commercialisation, l’évaluation de la diversité génétique intra et inter populations au sein de l’espèce sont nécessaires pour assurer son utilisation durable et sa conservation.

Spatial genetic structuring of baobab (Adansonia digitata, Malvaceae) in the traditional agroforestry systems of West Africa.

This study evaluates the spatial genetic structure of baobab (Adansonia digitata) populations from West African agroforestry systems at different geographical scales using AFLP fingerprints. Eleven populations from four countries (Benin, Ghana, Burkina Faso, and Senegal) had comparable levels of genetic diversity, although the two populations in the extreme west (Senegal) had less diversity. Pairwise F(ST) ranged from 0.02 to 0.28 and increased with geographic distance, even at a regional scale. Gene pools detected by Bayesian clustering seem to be a byproduct of the isolation-by-distance pattern rather than representing actual discrete entities. The organization of genetic diversity appears to result essentially from spatially restricted gene flow, with some influences of human seed exchange. Despite the potential for relatively long-distance pollen and seed dispersal by bats within populations, statistically significant spatial genetic structuring within populations (SGS) was detected and gave a mean indirect estimate of neighborhood size of ca. 45. This study demonstrated that relatively high levels of genetic structuring are present in baobab at both large and within-population level, which was unexpected in regard to its dispersal by bats and the influence of human exchange of seeds. Implications of these results for the conservation of baobab populations are discussed.

Home gardens: an assessment of their biodiversity and potential contribution to conservation of threatened species and crop wild relatives in Benin

Despite growing literature supporting the importance of home gardens (HG) as biodiversity hotspots, knowledge of patterns of their contribution to conservation of threatened species and crop wild relatives (CWR) across climate and culture in Africa is still limited. This investigation was conducted across three climatic zones to assess the floristic diversity of home gardens and the extent to which they contribute to conservation of threatened species and CWR. Overall, 240 home gardens were sampled and their floristic diversity assessed. The ecological importance of recorded species was determined per climatic zone using the importance value index (IVI). A cluster analysis was performed to group the species according to their IVI-values and a principal component analysis helped to identify the most important species. 285 species were inventoried throughout the study area. Home garden species’ diversity globally declined from the drier to the wetter zone but was highest in the transition zone. The average number of species found per HG was 10.1 and varied weakly across zones (9.07, Guineo-Congolean zone; 10.77, Sudano-Guinean zone; and 10.53, Sudanian zone). The most important home gardens species in the Sudanian, the Sudano-Guinean and the Guineo-Congolean zones were respectively: Abelmoschus esculentus (L.) Moench and Hibiscus asper Hook.f.; Solanum lycopersicum L. and Zea mays L.; Ipomoea aquatica Forssk. and Senna occidentalis (L.) Link. They were mainly vegetables and used as food and/or medicinal plant species. Twenty CWR and twelve threatened species were recorded and were also mainly used for food and medicinal purposes. Thorough research on socioeconomic factors supporting possession of HG and choice of managed species as well as indigenous management strategies of HG and dynamic of traditional knowledge related to HG may help to deeply assess home gardens’ effectiveness in biodiversity conservation.

Distribution of tree species along a gallery forest-savanna gradient: patterns, overlaps and ecological thresholds

Savannas intermingled with gallery forests are dynamic habitats typical in Africa. This study aims to determine if differences in species traits lead to non-overlapping distribution of gallery-forest and savanna species and abrupt transition between gallery forest and savanna. Tree species densities were measured in 375 plots of 1500 m 2 covering a total sample area of 56.25 ha along forty 3-km transects located at right angles to a riverbed with gallery forest into surrounding savanna. Location, vegetation type, soil physical properties, erosion and fire occurrence were recorded as site factors. Data analysis included the quantification of co-occurrence patterns, threshold indicator taxa analysis and fuzzy set ordination. The gallery forest–savanna gradient predicted floristic composition of plots with a correlation of 0.595 but its accuracy was locally modified by the occurrence of fire and the physical properties of soil that covered more than 30% of the range of residuals. The distribution of gallery-forest and savanna tree species did not overlap. Along the gallery forest–savanna gradient, savanna species gradually increased in density while gallery-forest species showed a community threshold at 120 m from the river beyond the width of gallery forest. The forest species driving this trend should play an important role in the dynamics of gallery forest–savanna boundaries.

Quantitative morphological descriptors confirm traditionally classified morphotypes of Tamarindus indica L. fruits

This study used quantitative descriptors to assess morphological variation of traditionally classified tamarind fruits and its relation to ecological conditions. Tamarind trees were sampled spanning locally recognized fruit morphotypes within three ecological zones. Twelve morphological descriptors were measured on 3000 fruits and seeds. Univariate and canonical discrimiant analyses performed on morphological descriptors revealed significant differences and confirmed morphotypes distinction as perceived by local people. Nevertheless, the variance components analysis showed substantial variations within morphotypes, suggesting a significant heterogeneity within fruits traditionally classified as belonging to the same morphotypes. To get a more powerful morphological discrimination, quantitative descriptors should hence be combined with locally perceived qualitative traits (pulp taste and colour). Observed variations were significantly correlated with ecological factors. Fruits’ and seeds’ size and mass tended to increase with humidity and decline with aridity. Results also indicated that fruit mass is a good predicator of pulp yield, although its predicting power differed among morphotypes. Outputs from the variance component analysis suggested that pending further genetic studies, germplasm collection should be done by sampling a moderate number of trees per morphotype, to ensure capturing a wide range of genetic diversity. The observed extensive variation has provided with relevant information for further improvement programs.

Biodiversity conservation in home gardens: traditional knowledge, use patterns and implications for management

There is increasing interest in home gardens (HGs) as biodiversity hot spots. However, knowledge on how sociocultural characteristics and environment influence knowledge and management of HG species is still limited. Eliciting these links helps illustrate how HG could conserve biodiversity. This study addressed the following hypotheses: (i) age and gender shape the knowledge of HG species; (ii) knowledge on HG species varies across phytochorological zones; (iii) use values (UVs) of HG species are correlated to their ecological importance and (iv) HG species is mostly used for food and medicinal purposes. Data were collected from 285 HGs, across three phytochorological zones of Benin, using semi-structured interviews. Quantitative analyses were performed using ethnobotanical indexes and statistical tests. Our results confirmed our assumptions except for hypothesis (i). Gender and age did not determine knowledge on HG species. Nevertheless, noticeable differences were encountered among the zones regarding species, knowledge and use types. UV and ecological importance were highly correlated. Our results support the point that HGs sustain food and medicine supply while contributing to conservation of local biodiversity. However, with modern mutations, HGs are unlikely to be preserved if they are not actively mainstreamed in production and conservation policies.

Tree species diversity promotes aboveground carbon storage through functional diversity and functional dominance

Abstract The relationship between biodiversity and ecosystem function has increasingly been debated as the cornerstone of the processes behind ecosystem services delivery. Experimental and natural field‐based studies have come up with nonconsistent patterns of biodiversity–ecosystem function, supporting either niche complementarity or selection effects hypothesis. Here, we used aboveground carbon (AGC) storage as proxy for ecosystem function in a South African mistbelt forest, and analyzed its relationship with species diversity, through functional diversity and functional dominance. We hypothesized that (1) diversity influences AGC through functional diversity and functional dominance effects; and (2) effects of diversity on AGC would be greater for functional dominance than for functional diversity. Community weight mean (CWM) of functional traits (wood density, specific leaf area, and maximum plant height) were calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multitrait functional diversity indices were computed. The first hypothesis was tested using structural equation modeling. For the second hypothesis, effects of environmental variables such as slope and altitude were tested first, and separate linear mixed‐effects models were fitted afterward for functional diversity, functional dominance, and both. Results showed that AGC varied significantly along the slope gradient, with lower values at steeper sites. Species diversity (richness) had positive relationship with AGC, even when slope effects were considered. As predicted, diversity effects on AGC were mediated through functional diversity and functional dominance, suggesting that both the niche complementarity and the selection effects are not exclusively affecting carbon storage. However, the effects were greater for functional diversity than for functional dominance. Furthermore, functional dominance effects were strongly transmitted by CWM of maximum plant height, reflecting the importance of forest vertical stratification for diversity–carbon relationship. We therefore argue for stronger complementary effects that would be induced also by complementary light‐use efficiency of tree and species growing in the understory layer.

The relative importance of climatic gradient versus human disturbance in determining population structure of Afzelia africana in the Republic of Benin

The study aimed to investigate the relative significance of effects of climatic variability and human disturbance on the population structure of the threatened species Afzelia africana Sm. ex Pers. in the Republic of Benin in West Africa. Forest inventory data such as regeneration density, tree diameter and total height were compiled from A. africana forest stands under different disturbance regimes in the three climatic zones of Benin. Multiple generalised linear models and non-linear diameter–height equations were fitted to contrast the individual effects of categorical variables, such as climatic zone and disturbance level. Results revealed significantly higher scaling coefficients in less drier regions and low-disturbance stands. The diameter–height relationship was more controlled by the climatic zone than by the disturbance level. Accordingly, the disturbance level contributed only to the intercept of the diameter–height model, whereas the climatic zone significantly influenced both intercept and slope. In addition, when climatic zone and disturbance level were considered as sources of variation in the diameter–height model, the former explained the greater marginal variance. It was concluded that climate has the greater effect on population structure of A. africana in natural stands.

Efficiency of inventory plot patterns in quantitative analysis of vegetation: a case study of tropical woodland and dense forest in Benin

The main issue in forest inventory is the reliability of data collected, which depends on the shape and size of inventoried plots. There is also a need for harmonisation of inventoried plot patterns in West Africa. This study focused on the impact of plot patterns on the quantitative analysis of two vegetation types of West Africa based on case studies from Benin. Twenty and fifteen plots of 1 ha each were demarcated in dense forest and woodland, respectively. Each 1 ha plot was divided into 100 quadrats of 100 m2 each and diameter at breast height (dbh) of trees was recorded in each quadrat. The required time to measuring trees diameter in each 1 ha plot was also recorded to compute the mean inventory effort. From the 100 quadrats in each 1 ha plot, 14 subplots of different shapes and sizes were considered by grouping together adjacent quadrats. The basal area of each subplot was computed and the relationship between estimation bias of the basal area and the size of subplots was modeled using Smiths Law (Smith 1938). The mean absolute error of the shape parameter c of Weibull distribution was computed for each of the subplot shape, size and direction. The direction and shape of subplots did not influence significantly (P > 0.05) the precision of the quantitative analysis of vegetation. However, square subplots were suitable in practice. On the contrary, plot size was significantly (P < 0.05) and inversely correlated to estimation efficiency. The optimal plot size for quantitative analysis of vegetation was 1 800 and 2 000 m2 with an inventory effort of 0.51 and 0.85 man-days per subplot in woodland and dense forest, respectively. It is concluded that use of standard sample sizes will help to harmonise a forestry database and to carry out comparisons at regional level.

Plants in traditional home gardens: richness, composition, conservation and implications for native biodiversity in Benin

Home gardens have received increasing attention and have been insistently presented as hotspots for agro-biodiversity over the last decades. However, apart from their exceptional high plant species diversity, there is little quantitative evidence of the effectiveness of plant species conservation in home gardens. This study examined this issue by assessing (i) the size and membership of garden flora and the contribution to the maintenance of the national flora, (ii) how home garden flora connects to the larger ecosystem it belongs to and (iii) the conservation status of plant species at the home garden level. 360 home gardens distributed in three agro-ecological zones and nine phyto-geographical districts in Benin were visited and inventoried. Diversity parameters at different taxonomic levels were calculated. Species accumulation and spatial occupancy, multivariate methods and rarity index were also used for data analysis. Findings showed that the 360 studied home gardens hosted up to 14.21% of plant species and 44.32% of plant families of the national flora. Home garden flora was constantly dominated by exotic plant species but strongly connected to their surrounding ecosystems, being composed of at least 60% of plant species from their phyto-geographical districts. Finally, home garden plant species were mostly rare and threatened at the home garden level. In this study, we acknowledge the contribution of home gardens to the maintenance of plant species diversity at regional and global levels than local level. Based on the observed prevalence of exotic species, HG effectiveness in sustainably conserving native plant species biodiversity remains questionable.