Floristic composition and turnover analysis in Dahomey Gap and the surrounding sub-humid Togolese mountain minor forest refuges: Importance for biogeography and biodiversity conservation in sub-Saharan Africa.

The origin of Dahomey Gap (DG) flora is one of the central biogeographical questions in sub-Saharan, which has been addressed in several studies. However, floristic evidence based on representative samples from the DG seems to be lacking in the scientific debate. The present study was conducted to fill this gap. Specifically, we assessed Togolese mountain riparian forests as minor forest refugia, examined their contribution to larger sub-Saharan forest refugia, and discussed the significance of these findings for biogeography and biodiversity conservation. Southwest Togo, West Africa, and sub-Saharan Upper Guinea Region Floristic data were collected in riparian forests through an intensive botanical inventory (n = 198; 50 × 10 m2). A comparative analysis was performed based on the floristic evidence related to forest refuges. The results showed significantly high species richness (868 species) and a high gamma and beta diversity associated with spatial turnover patterns. They also showed a high affinity between the study forests and large sub-Saharan forest refugia. Riparian forests share about 60% of their current species richness with large sub-Saharan forest refugia and contained refuge bio-indicator species. The floristic evidence, consistent with those of other studies, suggests that Togolese mountains would have very ancient origins and have experienced paleoclimatic events. The studied riparian would have served as refuges during recurrent climatic episodes. Our results support the minimal forest fragmentation hypothesis (network of refugia along rivers). However, they seem to be incompatible with the idea that the DG flora may be essentially a relic of the early Holocene. In sub-Saharan Africa, where maintaining a vast area of natural forest is difficult due to human pressure, efforts to preserve maximum species diversity should include a focus on the conservation of minor forest refuges, particularly in sub-humid mountain riparian zone.

Isolation and characterization of microsatellite markers for the threatened African endemic tree species Pterocarpus erinaceus Poir.

To study the genetic diversity and structure of the forest species Pterocarpus erinaceus Poir., seventeen polymorphic nuclear microsatellite markers were isolated and characterized, using next-generation sequencing. Three hundred and sixty-five (365) individuals were analyzed within fifteen (15) West African populations. The number of alleles for these loci varied from 4 to 30, and the heterozygosity varied from 0.23 to 0.82. The seventeen (17) primers designed here will allow characterizing the genetic diversity of this threaten species on its natural stands and to better understand the population differentiation mechanisms shaping it.

Vulnerability of African Rosewood (Pterocarpus erinaceus, Fabaceae) natural stands to climate change and implications for silviculture in West Africa.

Pterocarpus erinaceus is a native tree species of the Guineo-Sudanian and Sudano-Sahelian zones where natural stands are under constant pressure and heavily exploited for timber, animal feeding and others uses. A part from the overexploitation, climate change could also become a serious threat to the species natural distribution. For that purposes, this study aims to assess the vulnerability of P. erinaceus potential niche to climate change within its natural distribution area in West Africa. Niche predictions are based on 6,981 natural occurrence of the species and 19 global bioclimatic variables available through WorldClim. The future niche of the species is predicted according to three concentration pathways (RCPs 2.6, 4.5 and 8.5) of BC model for 2050 and 2070, thanks to Maxent software. P. erinaceus is currently reported from Senegal to Cameroon. Its potential niche covers the Sudano-Sahelian zone and the Dahomey gap on approximately 17.42% of the total area of these countries. In general, the niche of the species is not sensitive to climate change, regardless of the climate scenario and the year. Compared to its initial niche, the niche of the species will increase from 22.33% to 43.61% in 2050 and from 27.12% to 53.61% in 2070. However, this ecological expansion observed mainly in the Gulf of Guinea, will be associated with a considerable decrease in the Sahel and central Nigeria. This study shows the importance of promoting the development of innovative silvicultural strategies for the extension and restoration of natural stands of P. erinaceus in order to meet sustainably the timber needs of the West African region. It helps also to strengthening the roles of natural forests in providing ecosystem services and mitigating climate change effects.

[The sacred forests of Guinea: Between ecology and conservation]. / Les forêts sacrées de Guinée : entre écologie et conservation.

Guinea has very little ecological data available regarding its sacred forests. This study shows the important conservation role of these forests in a local context of strong human impacts. We present four representative case studies from the Sudano-Guinean zone in Upper Guinea. Our phytoecological inventories recorded a total of 431 species, 312 genera, and 87 families including 242 species, 187 genera, and 64 families in the forests. Twelve plant groups have been identified, including five in forests and seven in the surrounding vegetation. Geomorphology, texture, soil hydromorphism, microclimate, and human impacts are significant in explaining the spatial distribution of plant groups. The study reveals that in these Sudano-Guinean savannas, vegetation is dominated by micro-phanerophytes. The Guinean-Congolese flora is better represented in gallery forests.

Togo National Herbarium database.

This article describes the herbarium database of the University of Lomé. The database provides a good representation of the current knowledge of the flora of Togo. The herbarium of University of Lomé, known also as Herbarium togoense is the national herbarium and is registered in Index Herbariorum with the abbreviation TOGO. It contains 15,000 specimens of vascular plants coming mostly from all Togo's ecofloristic regions. Less than one percent of the specimens are from neighbouring countries such as Ghana, Benin and Burkina Faso. Collecting site details are specified in more that 97% of the sheet labels, but only about 50% contain geographic coordinates. Besides being a research resource, the herbarium constitutes an educational collection. The dataset described in this paper is registered with GBIF and accessible at https://www.gbif.org/dataset/b05dd467-aaf8-4c67-843c-27f049057b78. It was developed with the RIHA software (Réseau Informatique des Herbiers d'Afrique). The RIHA system (Chevillotte and Florence 2006, Radji et al. 2009) allows the capture of label data and associated information such as synonyms, vernacular names, taxonomic hierarchy and references.

Changes in the West African forest-savanna mosaic, insights from central Togo.

The West African forest-savanna mosaic, an important habitat for biodiversity and humans, is severely degraded, fragmented and modified by human activities. However, few studies have quantified the land cover changes observed over time and/or analysed the drivers of change. This study focused on Fazao-Malfakassa National Park, the largest in Togo, uses a combination of remote sensing, ground surveys and questionnaires to: (i) quantify vegetation changes, (ii) determine the drivers of change, (iii) compare results with findings elsewhere in the region and (iv) suggest management interventions. The images used were Landsat 5 TM, Landsat 7 ETM and Sentinel-2. Different vegetation indices were computed including: number of fragments, index of dominance, mean area of a vegetation type and mean annual expansion rate. In total, 300 people (including park staff and local populations) were interviewed using a semi-structured questionnaire. Results indicate that between 1987 and 2015 closed-canopy forest and tree-savanna became severely degraded and fragmented, following trends in other parts of the West African forest-savanna mosaic. The main drivers of change were agricultural expansion, bush fires and timber extraction. Observed changes and drivers altered with time: e.g. agricultural expansion was greatest during 1987-2001 (linked with political instability) while illegal timber extraction augmented during 2001-2015 (following increased timber value). Park staff and local populations' perceptions on drivers of change did not differ. Our study highlights that action is urgently needed if we are to preserve this important habitat, the biodiversity it hosts and the services it provides to humans. We suggest several management interventions, learning from successful interventions elsewhere in the region.

A first checklist of the Pteridophytes of Togo (West Africa).

BACKGROUND: The present work proposes, for the first time, a study exclusively focused on the diversity of Pteridophytes in Togo.The study was based on fieldwork that resulted in 869 new collections gathered between 2013 and 2017 in the country and on yet existing herbarium specimens kept at the Herbaria of Lomé and Paris. Thus, a total number of 1092 specimens collected throughout the country served as a basis for this work, to which were added the known, published occurrences of Pteridophytes for the country. NEW INFORMATION: At the end of this study, a total diversity of 134 species belonging to 53 genera and 25 families and 12 orders were recorded and documented for the country. It results in 73 newly cited species for Togolese flora, including 61 spontaneous species. Lycopodiopsida (18 species) and Polypodiopsida (116 species) classes are both represented. The Polypodiales order is the most represented with 97 species. The Pteridaceae and Aspleniaceae families are the most diverse with 24 and 22 species respectively. Finally, notes were provided on species distribution at national level.

Stochastic modelling of tree architecture and biomass allocation: application to teak (Tectona grandis L. f.), a tree species with polycyclic growth and leaf neoformation.

Background and aims: For a given genotype, the observed variability of tree forms results from the stochasticity of meristem functioning and from changing and heterogeneous environmental factors affecting biomass formation and allocation. In response to climate change, trees adapt their architecture by adjusting growth processes such as pre- and neoformation, as well as polycyclic growth. This is the case for the teak tree. The aim of this work was to adapt the plant model, GreenLab, in order to take into consideration both these processes using existing data on this tree species. Methods: This work adopted GreenLab formalism based on source-sink relationships at organ level that drive biomass production and partitioning within the whole plant over time. The stochastic aspect of phytomer production can be modelled by a Bernoulli process. The teak model was designed, parameterized and analysed using the architectural data from 2- to 5-year-old teak trees in open field stands. Key results: Growth and development parameters were identified, fitting the observed compound organic series with the theoretical series, using generalized least squares methods. Phytomer distributions of growth units and branching pattern varied depending on their axis category, i.e. their physiological age. These emerging properties were in accordance with the observed growth patterns and biomass allocation dynamics during a growing season marked by a short dry season. Conclusions: Annual growth patterns observed on teak, including shoot pre- and neoformation and polycyclism, were reproduced by the new version of the GreenLab model. However, further updating is discussed in order to ensure better consideration of radial variation in basic specific gravity of wood. Such upgrading of the model will enable teak ideotypes to be defined for improving wood production in terms of both volume and quality.

The Pteridaceae family diversity in Togo.

BACKGROUND: The Pteridaceae family is the largest fern family in Togo by its specific and generic diversity. Like all other families of ferns in the country, Pteridaceae are poorly studied and has no identification key. The objective of this study is to perform a taxonomic revision and list establishment of this family of leptosporangiate ferns in the light of current available knowledge about the family. Pteridaceae was also assessed in terms of its diversity and conservation status, this was conducted through the recent field data and the existing herbaria specimens. The current study permits to confirm the presence of Pteris similis Kuhn. which brought the number of Pteridaceae to 17 in Togo. NEW INFORMATION: This study provides first local scientific information about the fern flora of Togo. It confirmed the presence of Pterissimilis Kuhn. in Togo and brought the Pteridaceae family diversity to 17 species. A species identification key is provided for the easy identification of the Pteridaceae of Togo.

Molecular data reveal isolation by distance and past population expansion for the shea tree (Vitellaria paradoxa C.F. Gaertn) in West Africa.

While the genetic structure of many tree species in temperate, American and Asian regions is largely explained by climatic oscillations and subsequent habitat contractions and expansions, little is known about Africa. We investigated the genetic diversity and structure of shea tree (Vitellaria paradoxa,) in Western Africa, an economically important tree species in the Sudano-Sahelian zone. Eleven nuclear microsatellites (nuc) were used to genotype 673 trees selected in 38 populations. They revealed moderate to high within-population diversity: allelic richness ranged from R(nuc) = 3.99 to 5.63. This diversity was evenly distributed across West Africa. Populations were weakly differentiated (F(STnuc) = 0.085; P < 0.0001) and a pattern of isolation by distance was noted. No phylogeographic signal could be detected across the studied sample. Additionally, two chloroplast microsatellite loci, leading to 11 chlorotypes, were used to analyse a sub-set of 370 individuals. Some variation in chloroplast allelic richness among populations could be detected (R(cp) = 0.00 to 4.36), but these differences were not significant. No trend with latitude and longitude were observed. Differentiation was marked (G(STcp) = 0.553; P < 0.0001), but without a significant phylogeographical signal. Population expansion was detected considering the total population using approximate Bayesian computation (nuclear microsatellites) and mismatch distribution (chloroplast microsatellites) methods. This expansion signal and the isolation by distance pattern could be linked to the past climatic conditions in West Africa during the Pleistocene and Holocene which should have been favourable to shea tree development. In addition, human activities through agroforestry and domestication (started 10,000 bp) have probably enhanced gene flow and population expansion.

In vitro antiplasmodial activity of crude extracts from Togolese medicinal plants.

OBJECTIVE: To investigate the antimalarial effect of a few plants in Togo folk medicine. METHODS: After ethnobotanical survey, Opilia celtidifolia, Pavetta corymbosa (P. corymbosa) and Tamarindus indica (T. indica) were selected for screening. In vitro antimalarial tests were performed on crude extracts against fresh clinical isolates of Plasmodium falciparum using the semi microtest. RESULTS: Different IC(50) values of the extracts ranged from 2.042 to 100.000 µg/mL. According to the results, the methanol extract of aerial part of P. corymbosa followed by aqueous extract of fruit of T. indica were the most active (IC(50) of 2.042 and 4.786 µg/mL, respectively). Qualitative test revealed the presence of alkaloids in the leaves of P. corymbosa that may be responsible for the activity of the plant. CONCLUSIONS: Our study provides scientific evidence for usage of plant in the folk medicine, and further studies are needed for identification and purification of the active principles.