Chronic leaf-harvesting among other disturbances on the population dynamic of three fodder species in tropical savannahs, West Africa

Understanding the impact of leaf harvesting of fodder trees among other threats to forests is an important debate in ecology with implications for biodiversity conservation. This study assessed the impacts of leaf harvesting on the population structure of Afzelia africana Smith ex Pers., Khaya senegalensis (Desr.) A. Juss. and Pterocarpus erinaceus Poir.. The study assessed the density, abundance, frequency and regeneration dynamics of the three species in three categories of forests by installing fifty-four experimental plots of 1 ha in nine forest reserves in two ecological zones of Benin. The regeneration dynamics were monitored for 3 years (2021, 2022 and 2023). Data on regeneration density and large trees, diameter at breast height of large trees and regeneration diameter were collected in three forest categories according to anthropogenic disturbance. Mean tree diameter, mean density per hectare, abundance and regeneration dynamics for each of the three species revealed a significant difference (p< 0.05) according to anthropogenic disturbances and ecological zone. Mean tree density of the three species was higher (p< 0.05) for all three species in control forests. The highest mean tree diameter for all three species was found in forests subjected only to tree leaf harvesting. All three species have low abundance and high frequency of occurrence according to different anthropogenic disturbances. Regeneration density of the three fodder species changed slightly in forests where tree were logged and tree leaf harvested. Particularly Pterocarpus erinaceus was found to adapt better to different anthropogenic disturbances than Afzelia africana and Khaya senegalensis. Our results highlight the direct negative influence of leaf harvesting and timber exploitation on the population dynamics of woody forage species in terms of structure and density. Limiting leaf harvesting intensity to 50 % per tree may lead to better population dynamics of forage species.