Species enumeration and diversity of fire experimental plot at Olokemeji Forest Reserve, Ogun State, Nigeria

Abstract

The fire experimental plot of a total landed area of 0.174 ha was divided into three equal parts designated Plot A, Plot B and Plot C, corresponding to the early burnt, the late burnt and the control plot, respectively. Out of the 15 species of trees identified, six species belong to Fabaceae- Mimosoideae family and other families represented are Combretaceae, Meliaceae, Lamiaceae, Rubiaceae, Anacardiaceae, Urtiaceae and Sapotaceae. Gmelina arborea was the most abundant species and it was found in plot A, B and C. The diversity indices enumerated were Dominance index, Simpson index, Shannon index or diversity index and evenness index. Plot C had the highest abundance (species count), followed by Plot A and Plot B. While Plot B depicted a high dominance, dominance was low in Plot A and lowest in Plot C. This means that a particular species was dominating Plot B, which was Gmelina arborea. This Gmelina arborea also dominated Plot A but to a lesser extent compared to Plot B. Plot C was richer in species than Plot A and Plot B. The Shannon index was low across the three plots, but considerably highest in Plot C. Evenness index was moderate at Plot C, implying that there was an even distribution of tree species in Plot C, while evenness was low at Plot A and Plot B. Comparing the present data with the older data, it is clear that the fire experimental plot has undergone deforestation over the years, which requires urgent attention and reforestation.

Key words: cluster, dendogram, deforestation, burning, richness