The main objective of this study is to determine the different tree communities in the forest of Pobè and characterize their structure and ecology to contribute to the sustainable management of this forest. The forest of Pobè is located between the parallels 6° 57' 20" and 6° 58' 04" north latitude and 2° 39' 46" and 2° 40' 45" east longitude. The sampling used for data collection is one central plot of 1 hectare (100 m x 100 m) at the center of a square of 4 ha (200 m x 200 m). Twenty-five plots were installed and the dendrometric measurements were taken on the trees (dbh≥10cm). The regeneration inventory was done in 125 quadrats of 100 m 2 each at the rate of 5 quadrats per plot. The main results obtained showed that the forest of Pobè is diversified with 56 species of trees with an average density of 157 trees/ha and a basal area of 28.01m²/ha. The diameter structure shows that the trees of small diameters (≤40 cm) are the most represented, which presages a forest able of ensuring its own renewal. Two tree communities have been identified and characterized. The most representative is the community dominated by Triplochiton scleroxylon, Ceiba pentandra and Antiaris toxicaria and the community dominated by Triplochiton scleroxylon, Antiaris toxicaria and Terminalia superba. These two tree communities are well diversified and do not present a significant difference at the threshold of 5% for the diversity indexes calculated. The biggest threat of loss of biodiversity and the forest of Pobè degradation is anthropization, marked by the presence of vegetation fires, fuelwood cutting for charcoal production and the traffic paths often source of forest fragmentation.

The impact of anthropogenic activities on the spatiotemporal dynamics of the forest of Dogo-Kétou has been studied in relation to climate change observed in southeastern Benin. Especially, this study has detected the changes in climate parameters in southeast Benin from 1954 to 2016 and in forestland use from 1986 to 2018. A climatic break was detected, and the annual and monthly rainfall and temperature averages, the rainfall indexes, the concentration of precipitation, the number of rainy days according to the World Meteorological Organization and the bioclimatic aridity indexes were assessed. A GIS analysis was also performed based on Landsat images from 1986, 2000 and 2018 to detect the dynamic of land use and land cover of the classified forest of Dogo-Kétou. Excel 2016, Rx64 4.1.2, Rclimdex301, Khronostat1.01 and ArcGIS were used. The rainfall series showed a break in 1969. The segment from 1954 to 1968 was a period of excess rainfall with an average of 1420.46 mm/year. The segment from 1969 to 2016 was a rainfall deficit period with a reduction of 12 to 37% of rainy days and an increase of dry days for 21.4 days/year. In this last segment, southeast Benin experienced trends of its climate towards a sub-arid and arid climate. The agglomerations and bare soil of the forest of Dogo-Kétou increased to an area almost double the size between 1986 and 2018. The tree and shrub savannas gained in space from 12.1% in 2000 to 38.9% in 2018 and the dense forest and wooded savannas regressed by 52.6% in 1986 to 36.1% in 2000 then to 4.3% of the forest area in 2018. The subequatorial climate of southeastern Benin is gradually evolving towards a dry climate. The dense forest in this area is also gradually disappearing, giving way to savannas. This transformation towards the savannas was due to anthropogenic actions whose effects were strongly accentuated by climate change in this part of Benin and West Africa.

Les espèces exotiques envahissantes (IAS) peuvent avoir un impact négatif sur la régénération forestière. Cette étude a pour objectif d’évaluer les impacts de Chromolaena odorata sur la régénération arborée dans des forêts secondaires, ainsi que les moyens de les contrôler à bas prix. Les données ont été recueillies dans 77 parcelles rectangulaires de 0,5 ha dans des forêts secondaires du district de la Lama (Bénin, Afrique occidentale). Dans chaque parcelle, on a mesuré le dbh d’arbres et rejets (de dbh ≥ 10 cm) avec un ruban métrique, compté le nombre de rejets et mesuré la densité de recouvrement avec un densitomètre. La couverture de C. odorata, l’IAS ciblée, a été estimée dans une échelle de 0 (absence) à 100 % (couvert fermé). Les taillis et rejets ont été catégorisés dans trois groupes en fonction de leurs besoins de lumière (pionnier, non-pionnier léger besoin, et tolérant à l’ombre). C. odorata, densité de recouvrement, densité d’arbres, surface terrière, diamètre principal et recouvrement moyen ont été comptés et utilisés comme variables. Des coefficients de corrélation bilatérale entre les variables ont été calculés. Une analyse de régression, utilisant des modèles linéaires généralisés dans le logiciel R pour mettre en corrélation les variables du nombre de taillis/rejets par catégorie, a montré que C. odorata était en train d’éviter à la fois le développement des semis et des rejets de toutes les espèces, indépendamment de leurs catégories de besoin de lumière. Cependant, le couvert fermé avait une corrélation négative avec le couvert de l’herbe et peut être un moyen biologique de contrôler les IAS dans des forêts secondaires et dégradées.

This study examined the local perception on the climate changes and how these changes combined with anthropogenic pressures generated by the forms of use of the forest resources, impact the sustainability of the forests of Pobè and Dogo-Kétou in southeast Benin. The data were collected through an investigation of 148 and 139 local populations sampled respectively in the municipalities of Pobè and Kétou in the studied area. An interview guide and a structured research questionnaire were used to collect the data which were analyzed using the software Ri386 3.5.1. The mains results revealed that more than 98% of the local population living around these forests perceive the effects of climate change and anthropogenic activities are the main causes. The consequences of climate change from the social perception are diversified, such as the violent winds and the scarcity of rains. The prolonged droughts are also confirmed by 61% of local population in Kétou and 81% in Pobè. In these conditions, trees have a harder time of reproduction with a poor capacity of regeneration. The analysis of the vulnerability of these forests in relation to the use values (UV) revealed that the populations living near to Dogo-Kétou forest use so much the forest resources (UV>2.5) than those of Pobè (UV<2.5). So, moderate pressure was notified on Pobè forest. The forest of Dogo-Kétou is therefore more vulnerable than the forest of Pobè from the view of the pressures linked to the categories of uses relative to food, energy wood, service wood, non-timber forest products and medicinal use. For adaptation strategies, the local population revealed the enrichment of the forests by indigenous forest species (32% in Kétou and 19% in Pobè), the reforestation (76% in Kétou and 84% in Pobè) and the creation of private plantations (39% in Kétou and 57% in Pobè). However, the establishment of ethnobotanical family gardens, the reduction of wood consumption for energy to the detriment of domestic gas, sensitization, prayer (church and vodoun) are ways to better adapt a good resilience to climate change.Keywords: Climate change, adaptation strategies, reforestation, resilience, forests, Benin.