Statut mycorhizien de l'okoumé (Aucoumea klaineana Pierre) en régénération artificielle au sud Cameroun

Abstract

Mycorrhizal Status of Okoume (Aucoumea klaineana Pierre) in Artificial Regeneration in South Cameroon. This study described the mycorrhizal status of okoume (Aucoumea klaineana Pierre), an endemic burseraceae of the humid forests of Gabon. Like most tropical forest timbers, okoume forms arbuscular mycorrhizal symbiosis. Mycorrhizal root colonisation of okoume in artificial regeneration was investigated on trees planted between 1950 and 1989 in the Kienke Reserve of south Cameroon. Diameter at breast height (DBH) of okoume trees was on average 40 cm fifteen years after plantation. DBH was highly positively correlated to tree age but negatively to percent root colonisation (PRC). The highest PRC was reached fifteen years after planting, and declined thereafter, suggesting that adult trees of okoume could exert a control over mycorrhizal colonisation. In the absence of selective clear-cuttings, the relatively good growth performance of okoume outside of its natural growth range appears to be sustained by diverse mycorrhizal associations. For, almost all Glomalean genera were observed in okoume roots, independently of age, indicating that okoume is strongly mycorrhiza-dependent.

Keywords

• Okoume
• Arbuscular mycorrhiza
• Forestry plantation
• Cameroon