Limestone quarrying : the impact on the vegetation and landform of sagamu cement factory site, Sagamu, Southwestern Nigeria

Abstract

Species composition of the vegetation of several sites (worked; unworked; spoil heap in the quarry and its environs) in a cement manufacturing town, Sagamu, Southwestern Nigeria, was studied. The aim was to document the plant species compostition (biodiversity) of the quarry sites and its environs, which will provide baseline data for assessing the impact of limestone quarrying on the vegetation of the area. Two sampled plots, each measuring 25 m x 25 m, were studied in each site by complete enumeration of all the woody species and their girth measured at breast height. Limestone excavation in the area has altered the landform by creating new and varied habitats, namely, ponds and spoils heaps, which were not originally in the area. The spoil heaps have provided a haven for Pinus caribaea, a rare species of the vegetation of the area while Typha australis and fern are peculiar to the ponds and their banks.The original vegetation of the area has been greatly disturbed by agricultural activities and limestone quarrying. The present vegetation is a regrowth as evidenced by the small girth sizes of the woody species. Three distinct vegetation types, namely, gallery forest along water course, spoil heap vegetation dominated by Pinus caribaea and Terminalia catapa, and lowland secondary grasslsand vegetation dominated by Anthocleista vogelli, Alchornea spp and Spondia mombin .The spoil heap vegetation has fewer woody species but higher density than lowland secondary grassland vegetation with several species.The dominant grass species across all the sites were Andropogon tectorum, Panicum maximum, Penisetum purpureum and Sorghum bicor, and forb species were Aeschynomene cristata, Chromolaena odorata and Ipomea spp.

Keywords: Environment, excavation, quarrying, biodiversity, vegetation, species.