Modulation of functional traits and growth in Pericopsis elata seedlings in response to two contrasting light environments

The low natural regeneration of many exploited tree species in Central Africa highlights the need to more precisely define appropriate silvicultural practices. Understanding how seedlings adjust their functional traits and growth in full sunlight and under the shade of other trees is essential to optimise enrichment planting protocols. To address this topic on Pericopsis elata, an important light-demanding timber species exploited in Central Africa, 230 seedlings were transplanted in full sunlight or shaded environments (under Acacia auriculiformis). Twenty-three morpho-physiological and chemical traits were measured, alongside growth dynamics. Statistical analyses revealed high mortality (10.7%) in full sunlight during the first ten months after transplantation, with comparable mortality rates (about 13%) in both environments after three years in the field. However, logistic growth asymptotes were significantly higher in sunlight for diameter after 310 days and for height after 600 days of planting. Principal component analysis of functional traits revealed a conservative resource-use strategy in seedlings exposed to full sunlight, contrasting with a more acquisitive strategy under shade. Light environment explained over 58% of the variation in key traits such as specific leaf area, stomatal density, and maximum stomatal conductance. Stronger correlations among traits were observed under full sunlight, whereas these associations disappeared under shade, reflecting a shift along the resource acquisition-conservation continuum in response to light availability. These results provide one of the first experimental insights into how light influences growth and functional strategies in juvenile P. elata, indicating that shading with a canopy openness of about 20–65% promotes early establishment after transplanting seedlings, but a gradual thinning of shade trees is needed from the second year to enhance growth and survival.