By: EMERHI A. E.;
Abstract:
Extractives have significant impacts on wood utilization. They vary from species to species. This study was carried out to evaluate the variation in the extractive components of some selected tropical hardwood species in Nigerian mangrove and fresh water ecosystem. The species are Rhizophora racemosa, R. harrisonii Avicennia africana and Langucularia racemosa in the mangrove region and Symphoia globulifera, Alstonia boonei and Anthostema aubryanum , in the fresh water ecosystem. Wood samples and samples from their barks were collected from mangrove and fresh water forests and chemically analyzed to determine their extractive contents. The results indicated that the extractive content (E.C.) of the wood varied significantly with the species (p < 0.01). The overall mean value for all the species was 17.92%. The wood of the two red mangrove species (R. racemosa and R. harrisonii) had higher values of E. C. when compared with other wood species (Laguncularia racemosa, Avicennia africana, Symphoia globulifera, Alstonia boonei and Anthostema aubreyanum). The results also revealed some level of significant variations between the two forest types where the species were collected. The E. C. of both wood and bark varied amongst trees of the same diameter, and of different species. Heartwood’s E. C. was 1.44 times more than that of sapwood. Bark and wood’s E. C. decreased up the bole.
Keywords: Extractive Content, Mangrove species, Freshwater species, Variation, Age, Wood, Bark
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