Phytosociological Observations on the Vegetation of Burnt and Unburnt Areas Near Ibadan, Nigeria

Abstract

The area of study has a topography mainly of plains with occasional hills and is characterized by comparatively higher pH and conductivity on burnt sites. The weed communities existing on the unburnt sites were Axonopus-Eupatorium-Centrosema Community during the dry season (November to March) and Axonopus-Eupatorium-Commelina Community during the wet season (April to October). However, on the burnt sites, Imperata-Setaria-Panicum Community emerged. The dry season community on the unburnt site had comparatively the highest diversity index. Index of species association was high for Imperata cylindrica and Calapogonium mucumoides on burnt sites while for Axonopus compressus and Commelina diffusa during both dry and wet seasons on unburnt sites. The sominance-diversity relationships based on Simpson's Index were higher for the community on burnt sites. According to Kuchler's height classes, the height class 2 was predominant. The annual vegetation burning, in general, results in a preponderance of grasses and there were 12 grasses out of 29 species (41.4%) recorded on the burnt areas.