Exploring allometric relationships in immature oil palm in Southern Benin's smallholdings

2026

Article référencé dans le Web of Science WOS:001807439500001

Koussihouèdé H., Aholoukpé H., Flori A., Adjibodou J., Hinkati H., Ayizannon R., Amadji G., Clermont Dauphin Cathy

Trees Forests and People, 2026, 26, p. 101351 [15 p.]

Accurate estimation of oil palm aboveground biomass is essential for understanding growth dynamics, carbon accumulation, and resource-use efficiency, particularly during the immature stage when management practices strongly influence future productivity. However, few studies have developed non-destructive allometric equations specifically adapted to immature oil palms under African smallholder conditions. This study investigated the relationships between morphometric traits and total aboveground biomass of immature oil palm trees managed by smallholders in southern Benin. Morphometric measurements were conducted on 15 immature oil palm trees aged 2 to 3 years intercropped with maize or cassava. Tree height (H_max), girth circumference (Girth), and crown diameter (Crown_diameter) were measured on standing trees. Frond-related variables included petiole and rachis length (L), dry weights (DW) of petiole, rachis, and leaflets, dry weight of a 0.30 m rachis fragment sampled at the midpoint, and petiole cross-sectional dimensions. A total of 278 fronds were analysed. To predict the aboveground biomass, both linear regression and random forest (RF) models were applied. Results showed that maximum frond biomass is reached at frond rank 10, after which it gradually declines. Unlike the existing equations, frond biomass was poorly predicted by rachis biomass and petiole cross-section (R² < 0.40). the petiole length emerged as the best predictor of frond biomass (R² = 0.64). Similarly, the petiole length if the frond 10 was the most relevant predictor of total aboveground biomass in immature oil palms (R² = 0.94; RMSELOOCV = 0.94 kg). The INEAC vigour index was also a relevant predictor of total aboveground biomass, but to a lesser extent than simple morphometric variables such as frond length and height. Although the proposed equations should be interpreted cautiously because of the limited sample size and single-site design, this study provides an initial framework for rapid and non-destructive biomass estimation in immature oil palms under smallholder conditions. These results could support future assessments of biomass accumulation, carbon sequestration, and the effects of management practices such as intercropping on young oil palm development.

Sciences du monde végétal [076] ; Etudes, transformation, conservation du milieu naturel [082]

BENIN

Fonds IRD [F B010097507]

fdi:010097507