Managed woodlot revealed a trade-off between edible leaves and timber production in Vitex doniana Sweet (Lamiaceae)

Vitex doniana Sweet is a major wild-harvested tree resource for food in Benin. However, the species is under threats characterised by increasing human pressure on remnant populations. This study represents the first to explore species' response to biotic stress. We tested the response of V. doniana to coppicing and fertilization. Two stump heights (20 and 40 cm) in combination with three organic manure rates (0.5; 1 and 1.5 kg per seedling), with eight replicates were tested in a randomised complete block design. We used mixed effect models with pseudoreplication, and the maximum likelihood method to compare effects of fixed factors on sprouting vigour, sprout growth and biomass yield in the short (12 months) and medium (5 years) terms. Results indicated that stump height significantly affected sprouting and all growth parameters, in the short and medium terms. However, there seemed a delayed effect of manure. We found initial seedling growth also an important factor. The hidden effect of stump height on biomass yield is discussed. Findings clearly indicate a trade-off between edible leaves and timber production by managed woodlot. Implications of findings for further investigation of above and below ground biomass dynamics and resources allocation in treated trees are discussed.