Guinean Zone Research Articles

Stands diversity and population structure of five ethnoveterinary woody species according to climatic zone and human disturbance in Benin (West Africa)

Farmers continue to use medicinal plants, alone or in combination with veterinary medicines, to treat animal diseases, especially in developing countries. The study aimed to determine the effect of climatic zone and anthropic disturbance level on the diversity of the natural stand and structures of Morinda lucida Benth, Spondias mombin L., Terminalia leiocarpa (DC.) Baill, Crossopteryx febrifuga (Afzel. ex G. Don) Benth, and Vitex doniana Sweet, five plant species often used in ethnoveterinary medicine in Benin. A floristic inventory was conducted in 206 plots of 0.15 ha each, distributed across 6 forests/hunting areas as well as surrounding fields and fallow land. The data were analyzed using R software by calculating the importance value index and the population structural parameters (density, basal area, mean height, etc.). The results showed that the floristic composition of the habitats of the five target species varied by climatic zone and disturbance level. Morinda lucida, S. mombin, and V. doniana were available in stands undergoing heavy disturbance in the Guinean zone, whereas T. leiocarpa and C. febrifuga were more available in the Sudano-Guinean and Sudanian zones. Values of structural parameters of these species were higher in the Guinean zone than in the other two zones. Furthermore, the results of the diameter structure showed C-values ranging from 1 to 3.6, suggesting the predominance of young individuals. This suggests strong human pressure on the adults of studied plants. These results should be used to contribute to the sustainable use of these species. Recommendations are made for the sustainable use of these five species, especially T. leiocarpa and C. febrifuga, which were heavily exploited given their low availability in stands under high human disturbance.

Evaluation of Gridded Rainfall Products in Three West African Basins

In recent years, accessing rainfall data from ground observation networks maintained by national meteorological services in West Africa has become increasingly challenging. This is primarily due to high acquisition costs and the often sparse distribution of rainfall gauges across the region, which limits their use in hydrological studies and related research. At the same time, the rising availability of precipitation products derived from satellite/earth observations, reanalysis datasets, and in situ measurements presents exciting prospects for hydrological applications. Nonetheless, these datasets constitute indirect measurements, necessitating rigorous validation against ground-based rainfall data. This study comprehensively assesses twenty-three gridded rainfall products, including sixteen from satellites, six from reanalysis data, and one from in situ measurements, across the Senegal, Gambia, and Casamance River basins. Performance evaluation is conducted across distinct climatic zones, both pre- and post-resampling against observed rainfall data gathered from forty-nine rainfall stations over a six-year period (2003–2008). Evaluation criteria include the Kling–Gupta Efficiency (KGE) and Percentage of Bias (PBIAS) metrics, assessed at daily, monthly, and seasonal time steps. The results reveal distinct performance levels among the evaluated rainfall products. RFE, ARC2, and CPC notably yield the highest KGE scores at the daily time step, while GPCP, CHIRP, CHIRPS, RFE, MSWEP, ARC2, CPC, TAMSAT, and CMORPHCRT demonstrate superior performance at the monthly time step. During the rainy season, these products generally exhibit robustness. However, rainfall estimates derived from reanalysis datasets (ERA5, EWEMBI, MERRA2, PGF, WFDEICRU, and WFDEIGPCC) perform poorly in the studied basins. Based on the PBIAS metric, most products tend to underestimate precipitation values, while only PERSIANN and PERSIANNCCS lead to significant overestimations. Spatially, optimal performance of the products is observed in the Casamance basin and the Sudanian and Sahelian climatic zones within the Gambia and Senegal basins. Conversely, in the Guinean zone of the Gambia and Senegal Rivers, the rainfall products displayed the poorest performance.

Finding optimum climatic parameters for high tomato yield in Benin (West Africa) using frequent pattern growth algorithm.

Tomato is one of the most appreciated vegetables in the world. Predicting its yield and optimizing its culture is important for global food security. This paper addresses the challenge of finding optimum climatic values for a high tomato yield. The Frequent Pattern Growth (FPG) algorithm was considered to establish the associations between six climate variables: minimum and maximum temperatures, maximum humidity, sunshine (Sun), rainfall, and evapotranspiration (ET), collected over 26 years in the three agro-ecological Zones of Benin. Monthly climate data were aggregated with yield data over the same period. After aggregation, the data were transformed into 'low', 'medium', and 'high' attributes using the threshold values defined. Then, the rules were generated using the minimum support set to 0.2 and the confidence to 0.8. Only the rules with the consequence 'high yield' were screened. The best yield patterns were observed in the Guinean Zone, followed by the Sudanian. The results indicated that high tomato yield was associated with low ET in all areas considered. Minimum and maximum temperatures, maximum humidity, and Sun were medium in every Zone. Moreover, rainfall was high in the Sudanian Zone, unlike the other regions where it remained medium. These results are useful in assessing climate variability's impact on tomato production. Thus, they can help farmers make informed decisions on cultivation practices to optimize production in a changing environment. In addition, the findings of this study can be considered in other regions and adapted to other crops.

Determinants of farmers’ willingness to pay for improved cultivars of Macrotyloma geocarpum (harms) Maréchal and Baudet in Benin and Togo

IntroductionQuality seed is essential to satisfy food demand. This is also true for neglected crops especially those that are economically valuable such as Kersting’s groundnut (Macrotyloma geocarpum), which holds the potential to improve farmers’ livelihoods. In this study, we assessed the attributes that drove Kersting groundnut farmers’ willingness to pay for improved seeds.MethodsA total of 567 respondents were selected in the Northern Guinea and Southern Sudanian production zones in Benin and Togo using chain referral sampling, and they were then interviewed with a semi-structured questionnaire. Classification and regression trees, Ordinary Least Squared, and Tobit regression were combined to assess the relationship between the socio-demographic variables and farmers’ Willingness to Pay (WTP) and Amount they are Willing to Pay (AWTP).Results and discussionResults suggested that more than 90% of respondents involved in the production of Macrotyloma geocarpum were willing to access its improved seeds, including those who had already abandoned the cultivation of this crop due to constraints such as the very low seed yield of current cultivars, the difficulty to access seeds, and the cultivation practices. The factors which affected the amount farmers are willing to pay included the following: the low yield of current cultivars used by farmers, the expected yield of the improved variety, which should be higher than 1 ton per ha (1 t.ha−1), the socio-linguistic group affiliation, and the adoption level of improved agricultural technologies. The average amount fixed by seed companies that farmers were willing to pay for 1 kg of the improved seed was USD 5.35 but they have freely proposed to pay the average amount of USD 4.63 to access 1 kg of improved seed. The white-seeded cultivar was the most appreciated by farmers and was the most cultivated in the Northern Guinean Zone whereas the cultivation of the colored-seeded (e.g., black-seeded) cultivars was mainly noted in the Southern Sudanian Zone. Furthermore, the respondents indicated seed yield improvement and disease management as their main research needs to help increase the production of the crop. The findings of this research will help refine Macrotyloma geocarpum improvement programs to release farmer-needed varieties.

Bayesian approach and Imprecise Dirichlet Model for the selection of (underused/overused) medicinal plants in the Guinean zone of Togo

Identifying priority medicinal plants at the local level is crucial for the improvement of integrative and strong conservation solutions around these resources. This study was carried out to determine underused and overused botanical families, and, analyse the correlation between botanical families, used plant parts, and categories of treated diseases in the Guinean zone of Togo. Ethnobotanical field surveys conducted via semi-structured interviews (individuals/focus groups) among traditional healers and medicinal plant sellers helped to identify the rich diversity of medicinal plants used in the Guinean zone. Bayesian statistics and the Imprecise Dirichlet Model (IDM) were used to detect botanical families' level of use (under/overused). A matrix analysis via phylogeny coupled with a cladogram was carried out to highlight the preferences of users in plant parts and botanical families in the treatment of diseases. It appears that 12.43% of the local flora in the Guinean zone of Togo is used in traditional medicine. The most treated diseases with a high plant diversity are general and unspecified categories of diseases (228 plants), followed by cardiovascular diseases (133 plants). Both Bayesian and IDM approaches show that the most overused families are Amaranthaceae, followed by Combretaceae, Euphorbiaceae, Meliaceae, Myrtaceae, and Rutaceae. The underused families are Cyperaceae, Orchidaceae, and Poaceae. The leaves and roots are the plant parts in high demand for the preparation of medicinal drugs. The presence of chemical groups such as phenols, flavonoids, tannins, saponosides, coumarins, and alkaloids would justify the choice of a botanical family or specific plant parts for the treatment of a category of diseases. It is necessary to develop conservation strategies for overused plant families to ensure sustainability for future generations.

Changes in compound extremes of rainfall and temperature over West Africa using CMIP5 simulations

This study aims to characterize changes in compound extremes of rainfall and temperature over West Africa. For this purpose, data from CHIRPS observations, the ERA5 reanalysis, and twenty-four (24) climate models involved in the CMIP5 Project were analyzed. First, climate models were evaluated in terms of their capacity to simulate summer mean climatology and compound extremes during the historical period (1981–2005), and secondly, changes in compound extremes were examined under RCP8.5 emission scenario between the near future (2031–2055) and the far future (2071–2095) relative to the historical period. Despite the presence of some biases, the ensemble mean of the models well reproduces the compound extremes patterns over West Africa at the seasonal and intraseasonal timescales. The analysis over the historical period with CHIRPS/ERA5 dataset shows a strong occurrence of the dry/warm mode over the northern Sahel during the June-July-August-September period (JJAS; main rainy season) and over the Guinean region during the February-March-April-May season (FMAM; first and main rainy season). These strong occurrences are due to a weak and highly frequent precipitation recorded in these zones. The compound wet/warm mode is frequent in JJAS over the Sahel and the Sudanian zone (transition area between Sahel and Guinean regions), while in FMAM, its occurrence is maximum over the Guinean region. The study also shows that the dry/warm mode will increase in the whole Sahel (western and central) and in the Guinean zone in the near and far futures while the compound wet/warm mode will decrease in the whole region. This study suggests that the West Africa region will be prone to drought intensified by warmer temperatures and calls for climate action and adaptation strategies to mitigate the risks on rain-fed agriculture, energy, and on animals and human health.

Spatial distribution of goat breeds bred in Benin

Characterization of local goat breeds is an important step for the development of its breeding. This characterization cannot be done without knowing the size and the spatial distribution of the existing breeds. Thus, this work was carried out to study the spatial distribution of goat breeds bred in Benin. To achieve this, 498 breeders spread across the three climate zone of Benin were subjected to semi-structured individual interviews. The data collected were the socio-demographic characteristics of breeders, the number of breeds bred and the size of the herd per breed. Descriptive statistics, and the generalized linear model of Poisson family were used for data analysis. Results showed that breeders were mainly male (54.02%), married (88.15%) with a high rate of non-education (65.26%). The number of breeds bred by breeders in Guinean zone was 3 (West African Dwarf (WAD), Sahelian and Maradi goat) but 4 Soudanian and Soudano-Guinean zone (WAD, Sahelian, Maradi goat and Saanen). Despite the diversity of this breeds in the climate zone, only WAD breed was bred by more than 80% of breeders with a livestock size of 6133.

Floristic composition, structure and ecological drivers of woody stands of Detarium microcarpum Guill & Perr. and Detarium senegalense J.F.Gmel. in Benin

Detarium microcarpum Guill & Perr. and Detarium senegalense J.F.Gmel. are two species of wild trees that contribute significantly to the livelihoods of local communities in sub-Saharan Africa. Exploration of the ecological patterns of their population structure is, therefore, necessary to ensure long-term management. The aims of this study were to: (i) determine the floristic composition of the habitats of D. microcarpum and D. senegalense, (ii) assess the population structure of both species, and (iii) assess the influence of biotic and abiotic drivers on the structural parameters of these species. A total of 177 plots were installed in eight sites in Benin. The data collected included the dbh1.30 m, the crown diameter, the total height, and the type of regeneration (generative, sprout, and sucker). The topographical and soil parameters of the plots were also recorded. A generalized linear model (binomial negative regression) and ANOVA were used for the analysis of density and morphological features data, respectively. The floristic composition of D. microcarpum habitats was found to be relatively distinct (p = 0.001) from one zone to another. A significant difference (p = 0.001) in heterospecific individuals was also observed between the habitats of both species. The density of individuals of D. microcarpum decreased significantly from the Sudanian zone (4594 ± 207 stems/ha) to the Guinean zone (93.60 ± 11.90 stems/ha; p < 0.001). In the Sudano-Guinean zone where both species were found, the density of D. senegalense was very low (19.07 ± 7.64 stems/ha). The density of adult individuals of D. microcarpum was significantly high on gravelly soils. The regeneration of the species was negatively correlated with the slope, soil texture and basal area of heterospecific individuals. In D. senegalense, its regeneration was negatively correlated with elevation and positively with the density of its adult individuals. The height of both species of Detarium was positively associated with altitude. This study showed the effect of biotic and abiotic factors determining the population dynamics of Detarium spp. species and could be considered in the sustainable management of these species.

English

Interesting morphological traits in tree organs are essential for selecting the best plant germplasm. Variation in morphometric traits of leaf, fruit and seed of multipurpose tree Diospyros mespiliformis were studied in two climatic zones in Benin using 735 trees from 4 major habitats (provenances) in each climatic zone. Morphological trait measurements were combined with architectural parameters and analyzed using two-way ANOVA, principal components analysis and hierarchical clustering. Results indicated that significant differences were observed between leaves, fruits and seed morphological traits within climatic zones and habitats in terms of dimensions across the study area. Compared to the other three habitats (low dimensions), leaves from woodland showed large dimensions (&micro;L_leaf=130 mm, &micro;l_leaf=50 mm). Soudano Guinean zone recorded the highest fruits morphological traits values (&micro;d_fruit= 36 mm &micro;l_fruit=30 mm) while Soudanian zone had the lowest (&micro;d_fruit= 12 mm, &micro;l_fruit=8 mm). More seeds per fruit were recorded in woodlands and parklands. Out of these, hierarchical analysis grouped ebony morphotypes into four clusters. There was no significant correlation between the number of seeds per fruits and other fruit traits. However, significant and strong positive correlations were found between morphometric characters, bearing and architectural parameters (R = 0.96). The provenance significantly affected variations in organ-related traits. &nbsp;Correlation relationships suggested morphotypes for breeding improvement. Interesting and desired characteristics delineating individuals and populations can guide future selection of targeted ebony trees with the aim of improving high-value species in agroforestry domestication program. &nbsp; Key words: Diversity, domestication, environmental factors, morphological descriptors, multivariate analysis.

Leaf and fruit characteristics of Parkia biglobosa (Jacq.) Benth according to agro climatic zones and land use in Southern Mali

A study was conducted in southern Mali to characterized Parkia biglobosa populations in the aim to contribute to the domestication of the species. Fields and fallows in the north sudanian, south sudanian and north guinean zones were concerned. Adult trees were marked in plots of 0.25 ha each and leaves and fruits were harvested from each tree for characterization. Petiole and laminar length, number of pairs of pinnae and leaflets, pedicel and pod length, pod wide, pod and seed weight, number of seed per pod were measured. The north guinean zone showed the highest number of pairs of pinnae and leaflets, the longest pods (23.06±9.91 cm in the fields), the highest mean seed weight (3.74±0.96 g in the fields) and the highest mean number of seeds per pod (17 ± 3 seeds in the fields). The South Sudanian zone showed the longest pedicels (3.85±1.08 cm in the fallows), the highest mean laminar length (18.02 cm) and mean petiole length (6.45 cm) in the fields but the same mean number of seeds per pod as for the north Guinean. The north Sudanian zone showed the widest (17.88±7.98 cm in the fields and 18.24±2.11 cm in the fallows) and heaviest (14.87±3.95 g in the fallows) pods. Leaf variables like the number of pairs of pinnae and leaflets seem to be influenced by the climatic gradient. The others leaf, pod and seed variables seem not to be influenced by the climatic gradient. These findings suggest that many leaf and fruit variables are controlled by endogenous factor that could be genetic. However, the manifestation of the endogenous factor seems to be influenced by factors such as environment and management practices.

MOLECULAR CHARACTERIZATION OF RHIZOBIA STRAINS ASSOCIATED WITH MUNGBEAN (VIGNA RADIATA), IN SOILS OF SUDANO-GUINEAN AND SAHELIAN AGROECOLOGICAL ZONES OF MALI

In the Sudano-Guinean and Sahelian zones of Mali, the decline in soil fertility is a key challenge for a sustainable enhancement of agricultural productivity. In addition, studies on the diversity of bacteria associated with Mungbeans are rare, with very few studies conducted on their identification and molecular characterization in the soils of the major agricultural production basins in the Sudano-Guinean and Sahelian Guinean zones of Mali. This study was therefore motivated not only by these different challenges of productivity and soil fertility, but also by the numerous nutritional and agronomic interests of mung beans and the possibility of using its associated bacteria as bio-fertilizers. It aims at contributing to the improvement of mung bean (Vigna radiata L) productivity and the promotion of its cultivation using inocula based on indigenous and efficient bacteria. To achieve this objective, soil samples were taken from various farmers' fields in the two studied areas. The Physico-chemical characteristics of the soils were determined, and trapping trials were conducted in the greenhouse on these soils with Mung bean as the trap plant. The nodules formed on the plants were harvested, the rhizobia contained in these nodules were isolated, the IGS of the 16S-23S rDNA of the isolates was analyzed using PCR-RFLP, and an inoculation test was carried out in a growth chamber to verify the infectivity of the isolates. Eighty-three (83) isolates divided into two groups according to their color (whitish, yellowish) and three (03) IGS types (I, II, III) were encountered with a large dominance of IGS type I in the Guinean zone and that of IGS types I and II in the Sahel zone. Two (02) isolates of type IGS I showed a higher infectivity. These results show a low diversity of rhizobium strains associated with Mung bean in the studied soils. It would be interesting to extend this study to other areas of Mali for strains that associate with Mung bean.

Mycorrhizal Status of Natural Stands of Pterocarpus erinaceus Poir. (Fabaceae) in Sudanian and Guinean Zones of West Africa

Background and Aims: The sylviculture of Pterocarpus erinaceus is still in its infancy due to lack of information on its biology. The aim of this study is to investigate its mycorrhizal status in order to better address its sylviculture.&#x0D; Place and Duration of Study: The study was performed on the field from May 2019 to December 2020 and data were analyzed at the laboratory from January to March 2021.&#x0D; Methodology: The frequency and intensity of mycorrhization were determined under a microscope after staining with trypan blue of fine roots collected at a depth of 20 cm under adult plants at 5 sites, 3 in the Guinean zone and 2 in the Sudanian zone in Togo. The spore density was obtained on soil samples taken at the same depth under the same trees.&#x0D; Results: Results indicate, without significant differences (P value = 0.166) among sites, and show that P. erinaceus is frequently mycorrhized (88% to 94%). However, there were significant differences (P value = 0.001) in spore densities between sites located in the Sudanian zone (16.53 ± 1.25 and 10.66 ± 0.71 spores per gram of soil – SPGS – respectively for the Fazao-Malfakassa and Oti-Kéran-Mandouri) and those located in the Guinean zone (4.54 ± 0.3, 2.93 ± 0.43 and 3.76 ± 1.01 SPGS respectively at Abdoulaye, Hahomegbe and Togodo). There are significant differences between mycorrhization intensities Togodo which has a mycorhization intensity of 33.52 ± 2.54 and other sites. The redundancy analysis carried out by taking into account substrates’ chemical characteristics shows that spore density remains low when phosphorus and nitrogen are important in the rhizosphere whereas the intensity of mycorhizations is low when PHKCl is high.&#x0D; Conclusion: This study provided evidence of mycorrhizal symbiosis in Pterocarpus erinaceus whether in the Sudanian or Guinean zone. Chemical quality of the growing substrate has an influence on parameters of mychorization. Further studies should therefore allow an assessment of the degree of dependence of this species with respect to the possible benefits associated with this symbiosis.

English

A study was conducted in southern Mali to contribute to the domestication of Parkia biglobosa. Three agro climatic zones (North Sudanian &ldquo;NS&rdquo;, South Sudanian &ldquo;SS&rdquo; and North Guinean &ldquo;NG&rdquo;) and two stands (field and fallow) were concerned. Three plots of 0.25 ha each, were installed in each stand. Diameter at Breast Height (DBH), Total Height (TH) and Crown Diameter (CD) of adult trees were measured. The effect of agro-climatic zone on growth parameters was significant. The South and North Sudanian zones showed significantly higher means of DBH, TH and CD compared to the North Guinean zone. The mean DBH varied from 45.46 cm (NG) to 65.96 cm (NS). The mean TH varied from 10.68 m (NG) to 12.59 m (NS). The mean CD in the field stand varied from 10.50 m (NG) to 16.12 m (SS) and in fallow stand it varied from 11.21 m (SS) to 13.64 m (NS). Stand effect was not significant but the interaction zone*stand was significant. The effect of agro-climatic did not display an influence of the climatic gradient, suggesting that management practices played an important role in the growth of this species. &nbsp; Key words: Domestication, fallow, field, growth parameters, management practices, Parkland species.

Relations between the ecological conditions and the properties of Pterocarpus erinaceus Poir. wood from the Guinean-Sudanian and Sahelian zones of West Africa

AbstractPterocarpus erinaceus (Poir) is currently the most exploited and threatened spontaneous tree species in the Guinean-Sudanian and Sudano-Sahelian zones in West Africa. This work analyzed the density and color parameters of P. erinaceus wood in the phytogeographic zones (Sudanian, Guinean and Sahelian) in three countries in West Africa (Togo, Burkina Faso and Niger). The results obtained by studying 451 specimens taken from 95 trees showed significant differences in basic density and color parameter values (P &lt; 0.001) based on phytogeographic zones. Individual tree samples from the Sahelian zone were denser (780 ± 63 kg · m − 3), darker (L* = 48.3 ± 0.6) and redder (a* = 8.2 ± 2) than those in the Guinean zone (basic density = 684 ± 53 kg · m−3; L* = 59.7 ± 0.5; a* = 6 ± 0.2) and the Sudanian zone (basic density = 725 ± 70 kg · m−3; L* = 53.7 ± 0.40; a* = 7.30 ± 0.2). At intra-tree scale, the results did not show a significant variation of basic density according to the number of rings counted from the pith (P &gt; 0.05). This indicated that the age of the trees has little influence on the basic density of P. erinaceus wood.

Ecophenotypic variation of fruits, natural seed germination and seedling growth of Picralima nitida in Dahomey Gap: implication for conservation and valorization

Picralima nitida is an important African medicinal plant species threatened in the Dahomey Gap. It is used in pharmaceutical industries and traditional medicine to treat several diseases. Despite its importance, this the species faces a serious conservation problem. It is rare, especially in the Dahomey Gap countries in contrast to the Guinean zone. The present study aims to contribute to the conservation of P. nitida by assessing the ecophenotypic variation of the fruit, natural seed germination and seedling growth. A total of 1,200 fruits were collected in two phytodistricts of Dahomey Gap to evaluate the morphotypes. The seeds were evaluated for natural germination with different substrates. The results on ecophenotypic variation and natural seed germination revealed no significant difference (p > 0.05) between the fruits from the two phytodistricts. However, three morphotypes of fruits were obtained with significant difference (p < 0.05). Morphotype 1 gathered large, round and heavy fruits, morphotype 2 fruits were elongated oval-shaped, and morphotype 3 fruits were short, round and light. The highest germination rate (73.33%) was obtained with morphotype 1 seeds on the substrate composed of 100% top soil. The fruits from the phytodistrict of Pobe had seeds with the highest rate of germination (55.55%) on the substrate composed of 100% top soil. The use of organic matter in the substrate of germination stimulated the growth of P. nitida seedlings after seed germination.

Habitats of antlions larvae (Neuroptera: Myrmeleontidae) in the Sudano-Guinean and Sudano-Sahelian zones of Cameroon

Antlions (Insecta: Neuroptera) are flying insect associated with sunny weather at adult stage. During larval stage, xerophilous insects they are familiar to arid soils with critical temperature, hygrometry and luminosity. These 3 climatic parameters are used to discriminate among larval habitats of antlions in the Soudano Guinean and Soudano Sahelian Savannah of Cameroon. Investigations made during 3 years from 2015 to 2018,consisted in survey of larvae’s funnels. At the level of each active pit-traps, the 3 parameters were recorded during the whole dry season. Analysis of data computerised pointed out that larvae of Cueta bourborni Navas 1935, and those of Cueta sp, are frequent within sites that are warm (40.57±0.64°C to 52.14±4.08°C); dry (10.91±0.82-16.81±2.74%rh) and lighted (94380.2 ±16109.4 lux) habitats. On the other hand, larvae of Myrmeleonquinquemaculatus Hagen 1853 are associated with sites that are: humid (75.46±4.50% RH), cloudy (448.232±300. 491 lux) with tendency to moist (22.11±0.88°C to 28.10 ±2.14°C). Presence of C. bourbonni sometimes in the moisty Soudano Guinean zone could only indicate episode of warming.&#x0D; Keywords. Antlions habitats, global warming, temperature, luminosity, Hygrometry

A High-Resolution Cropland Map for the West African Sahel Based on High-Density Training Data, Google Earth Engine, and Locally Optimized Machine Learning

The West African Sahel Cropland map (WASC30) is a new 30-m cropland extent product for the nominal year of 2015. We used the computing resources provided by Google Earth Engine (GEE) to fit and apply Random Forest models for cropland detection in each of 189 grid cells (composed of 100 km2, hence a total of ~1.9 × 106 km2) across five countries of the West African Sahel (Burkina Faso, Mauritania, Mali, Niger, and Senegal). Landsat-8 surface reflectance (Bands 2–7) and vegetation indices (NDVI, EVI, SAVI, and MSAVI), organized to include dry-season and growing-season band reflectances and vegetation indices for the years 2013–2015, were used as predictors. Training data were derived from an independent, high-resolution, visually interpreted sample dataset that classifies sample points across West Africa using a 2-km grid (~380,000 points were used in this study, with 50% used for model training and 50% used for model validation). Analysis of the new cropland dataset indicates a summed cropland area of ~316 × 103 km2 across the 5 countries, primarily in rainfed cropland (309 × 103 km2), with irrigated cropland area (7 × 103 km2) representing 2% of the total cropland area. At regional scale, the cropland dataset has an overall accuracy of 90.1% and a cropland class (rainfed and irrigated) user’s accuracy of 79%. At bioclimatic zones scale, results show that land proportion occupied by rainfed agriculture increases with annual precipitation up to 1000 mm. The Sudanian zone (600–1200 mm) has the highest proportion of land in agriculture (24%), followed by the Sahelian (200–600 mm) and the Guinean (1200 +) zones for 15% and 4%, respectively. The new West African Sahel dataset is made freely available for applications requiring improved cropland area information for agricultural monitoring and food security applications.

Evaluation and Calibration of Alternative Methods for Estimating Reference Evapotranspiration in the Senegal River Basin

Reference evapotranspiration (ET0) is a key element of the water cycle in tropical areas for the planning and management of water resources, hydrological modeling, and irrigation management. The objective of this research is to assess twenty methods in computing ET0 in the Senegal River Basin and to calibrate and validate the best methods that integrate fewer climate variables. The performance of alternative methods compared to the Penman Monteith (FAO56-PM) model is evaluated using the coefficient of determination (R2), normalized root mean square error (NRMSE), percentage of bias (PBIAS), and the Kling–Gupta Efficiency (KGE). The most robust methods integrating fewer climate variables were calibrated and validated and the results show that Trabert, Valiantzas 2, Valiantzas 3, and Hargreaves and Samani models are, respectively, the most robust for ET0 estimation. The calibration improves the estimates of reference evapotranspiration compared to original models. It improved the performance of these models with an increase in KGE values of 45%, 32%, 29%, and 19% for Trabert, Valiantzas 2, Valiantzas 3, and Hargreaves and Samani models, respectively. From a spatial point of view, the calibrated models of Trabert and Valiantzas 2 are robust in all the climatic zones of the Senegal River Basin, whereas, those of Valiantzas 3 and Hargreaves and Samani are more efficient in the Guinean zone. This study provides information on the choice of a model for estimating evapotranspiration in the Senegal River Basin.

Status and population structures of three anthelmintic tree species along climatic gradient in Benin and the implications for conservation

Smallholder farmers make intensive use of anthelmintic plant species in the traditional treatment of animal parasitic infections. As a result, populations of these plant species are exposed to increased disturbances such as plant harvesting, threatening their stability. Information on population structure of threatened plant species is important not only for understanding their ecological status but also for conservation and restoration purposes. Using floristic and structural data from 61 plots of 0.09 ha each, we assessed the population structures of the three anthelmin- tic species (Bridelia ferruginea, Mitragyna inermis, and Combretum glutinosum) along the climatic gradient (Guinean, Sudano–Guinean and Sudanian climatic zones) in Benin. Structural characteristics (tree density, basal area, mean diameter, tree height), and species-specific diameter and height distribution were assessed. Results showed that B. ferruginea was found in all three climatic zones, but more prominent in the Sudano–Guinean zone with a scarcity index of less than one per cent. Mitragyna inermis and C. glutinosum were only observed in the Guinean zone and Sudanian zone, respectively. Bridelia ferruginea population structures, especially density and basal area, varied significantly among climatic zones. Diameter- and height-class distributions for the three species exhibited a bell shape with a tendency to right skewness, indicating a predominance of younger trees. These results suggest that the three species are not currently threatened in Benin; however, it would be necessary to prevent overexploitation to guarantee future sustainability.

Influence of the Conditions of Exposure of Pigs Carcasses (&amp;lt;i&amp;gt;Sus scrofa domesticus&amp;lt;/i&amp;gt; L.) on the Egg-Laying Delay of Necrophagous Diptera in the Guinean Zone of Ivory Coast

A decaying cadaver is particularly attractive to necrophagous insects, more specifically Diptera. These are the first to lay their eggs on corpses. For the post mortem interval determination, the entomologist needs to know the precise time of the first egg-laying. The objective of this study is to determine the egg laying delay of these insects on a cadaver exposed in different conditions in the Guinean zone of Cote d'Ivoire. To do this, our work was been carried out in a natural environment at the National Agronomic Research Center. The experimental setup consisted of four types of wire mesh cages corresponding to the following cases: cadavers exposed to the open air or control cadavers, semi-immersed cadavers, cadavers wrapped in a shroud and suspended cadavers. Work on the site has been made from 29 October to 5 November 2019. The spawning period in species of Calliphoridae, was shorter on control and suspended cadavers. In Sarcophagidae, we noted a larviposition late on the suspended cadavers. Muscidae and Fanniidae, which intervened later on the decomposing corpses, were not observed on the suspended cadavers. These carcasses quickly dried out, no longer being able to provide nutrients essential for the proper development of larvae of species of these Diptera families. Depending on the accessibility of the corpses to necrophagous insects, the first egg-laying of Diptera were observed after 6 hours of exposure and the last after 174 hours. The exposure conditions of the corpses significantly influenced the time taken to lay the main necrophagous Diptera. As the first egg-laying of the flies occurs in the first moments after death, as long as the corpses is accessible, the results obtained during these experiments should be taken into account by the expert entomologist, in the estimation of the interval post-mortem upon discovery of a corpse.