The aim of this study is to assess the relationship between pollen rain, climatic parameters and surface sediments in the Sudano-Guinean zone. Pollen rain was evaluated from the pollen analysis of 30 samples of surface sediments treated by the method of Faegri and Iversen (1989). The sediments were subjected to treatment with Hcl 10%, HF 10% and acetolysis. The floristic inventory was carried out on 500 m2 plots in the Zou, Bassila and South Borgou phytodistricts in the Sudano-Guinean zone. A total of 30 surveys were obtained and submitted to the R software (R Core Team, 2019) for the various analyses. The climatic factors listed are temperature, rainfall and altitude. Pollen analysis identified a total of 271 taxa. The phytodistrict of Zou has the highest pollen richness (97 taxa) while the lowest is found in Bassila (60 taxa). Shannon's diversity index is between 3 and 4 and Piélou's equitability index is between 0.596 and 0.632. The results obtained on the relationship between pollen diversity, climatic parameters and soil characteristics in the Sudano-Guinean zone in Benin, allow us to affirm that soil texture and structure, climatic parameters such as altitude and average temperature condition the deposition and conservation of pollen and positively influence the pollen abundance in surface sediments.

The present study aims to: (i) check its abundance and distribution Sterculia setigera Del. in Togo according to biophysical factors and (ii) forecast its potential suitable habitat. S. setigera trees (DBH ≥ 10 cm) were numbered and human activities were recorded within 518 plots. Geographic Information System offers applications for evaluation of the abundance in relation to anthropogenic threats, human population density, elevation, annual mean temperature, annual mean precipitation, and types of soils. The distribution model based on Maximum Entropy was used to forecast the potential suitable habitat using the species occurrence data and environmental data. Occurrence data were gathered from fieldworks, herbarium records, and scientific published papers. Environmental data were formed by 19 bioclimatic variables and altitude data. Based on cross-correlations among variables, variables’ contribution, and jackknife test of variables’ importance, six bioclimatic variables were selected for model running. The two main variables that contributed towards predicting the potential suitable habitat were the annual precipitation and the temperature seasonality. The abundance of the species is more positively correlated by the soil type and the topography while it is negatively correlated to rainfall. Anthropogenic threats’ importance increase from the south to the north of the country while human population density decrease. The most suitable habitat of S. setigera were predicted in eco-floristic zones I and III of Togo. Further studies on the nursery, the regeneration, the cultivar selection and the assessment of the future climate impact will be a great asset for its sustainable management and domestication.