Effects of exotic tree plantations of teak (Tectona grandis) and gmelina (Gmelina arborea) on a forest soil in south‐western Nigeria

Department of Geography, University of Ibadan, Nigeria.
Soil Use and Management (Impact Factor: 1.97). 01/2007; 6(1):43 - 45. DOI: 10.1111/j.1475-2743.1990.tb00796.x

ABSTRACT The properties of soil under 15-year-old plantations of gmelina (Gmelina arborea) and teak (Tectona grandis) were compared with logged forest soil in south-western Nigeria. The soil was significantly denser in the 0–10 cm layer of plantation soil and total porosity less than that of forest soil. Organic carbon was significantly greater in the 0–10 cm layer of forest soil. Similarly, the concentrations of total N, exchangeable Ca, Mg and K were greater under forest soil, but the concentrations of available P were similar under all three ecosystems. The smaller organic carbon and nutrient content of plantation soil is mainly due to its more open organic matter and nutrient cycles and nutrient immobilization in the fast-growing exotics.

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    ABSTRACT: This paper examines the depletion of Nigeria's natural forest resources consequent upon exploitation without adequate conservation. It also examines plantation forestry as the government's strategy for replenishing the country's lumber resources. It argues that it is ecologically unwise to clear-fell reserves of native rain forest and replant them with monoculture tree plantations, especially of the exotics, teak and gmelina, and stresses the need to conserve the rain forest ecosystem in southern Nigeria.
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