Organic certification is associated with the biodiversity and structural dynamics of Vitellaria paradoxa C.F. Gaertn. Stands in West African savanna ecosystems

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Résumé

In recent years, organic certification of non-timber forest products, such as shea nuts, has emerged as a market based mechanism for promoting sustainable harvesting and biodiversity conservation. This study aimed to: (i) compare tree (adult and seedling) species richness, density, and diversity between certified and non-certified Vitellaria paradoxa stands, (ii) assess differences in the demographic and structural attributes of V. paradoxa populations between certification regimes, and (iii) evaluate population structure across certification regimes. A total of 31 sample plots were established using a stratified sampling design based on certification regimes. Species diversity was assessed using Hill numbers, and ANOVA was applied to test differences between certified and non-certified forest blocks. In total, 85 woody species were recorded in V. paradoxa stands, with higher
species richness in certified forest blocks (61 species) than in non-certified blocks (54 species). Species richness and diversity differed significantly among certification regimes (p < 0.001) for the juvenile stratum. Dendrometric characteristics of V. paradoxa revealed higher population density in certified forest blocks (85.71 ± 74.70 individuals/ha) compared to non-certified forest blocks (16.66 ± 10.32 individuals/ha). Diameter class distributions indicated an unstable population structure in both regimes for the adult stratum. However, the inverted J-shaped height class distribution observed in certified forest blocks suggests good regeneration potential. These findings suggest that forest certification may be a good policy option to conserve biodiversity. This study also serves as a baseline to ensure the long-term conservation of V. paradoxa populations in West Africa.

Mots-clés

Shea nuts, Woody species, Conservation, Forest management