Species composition and diversity in IITA Forest Reserve, Ibadan, Oyo State, Nigeria

Assessment of plant species compositionand diversity of International Institute ofTropical Agriculture (IITA) Forest Reserve,Ibadan, Nigeria was carried out to facilitateforest conservation and restoration. Twotransects, each measuring 500m long werelaid systematically for the study. Next, ten25m x 25m sampling plots were demarcatedon each transect for enumeration andidentification of trees, shrubs and climbers.Further, 1m x1m subplots were demarcatedfor enumeration and identification of herbsand lianas. Shannon-Wiener diversity andSimpson indexes were used to assess speciesdiversity, evenness indices and richness.Species richness in the Reserve was: trees(58), shrubs (26), climbers (15), herbs (6)and lianas (4). Species diversity (H´) andspecies evenness (E) were: trees (3.18,0.41), shrubs (2.97, 0.72), climbers (2.31,0.67), herbs (1.36, 0.78), and lianas (0.73,0.69), respectively. Stand density was 1255trees/ha while basal area was 23.10m2ha-1.There was a decrease in the number ofindividual trees in various diameter classesas size increased. The Forest Reserve wasdominated by Malvaceae, Leguminosae,Apocynaceae, Euphorbiaceae, and Moraceaefamilies. Newbouldia laevis, Sphenocentrumjollyanum, Acacia ataxacantha,Chromolaena odorata, and Cnestisferruginea were the most abundant trees,shrubs, climbers, herb and lianas,respectively. Species population structureindicated high species diversity; therefore,management plan should be put in place forspecies conservation