Carbon Stock in Different Pools across Different Vegetation Structures in a Tropical Rainforest in Ile-Ife, Nigeria

Carbon stock in the soil pool, shrubs, herbaceous plants and standing floor litters across different vegetation structures were investigated in a tropical rainforest with the aim of providing information on the carbon stock in these pools across these physiognomies. Two plots, each of 20x20 cm were marked out at each site, five lines transects were systematically laid in each plot and a quadrat of 1×1 m was established at every 2 m point where the above ground biomass of shrubs and herbs were collected by clipping at 2 cm above the ground, oven dried at 70°C to a constant weight and weighed. Standing floor litters were randomly collected at every three month intervals for a period of one year at five points using a quadrat size of 50×50 cm for a period of one year; sorted out into leaves and wood, oven dried at 70°C to a constant weight. Five soil samples were also randomly collected from each plot at 0-15 cm depth, air dried, sieved and analyzed for total organic carbon. Carbon stock ranged from 0.27-0.74 Mg C ha-1 in the herbs, 1.86-3.51 Mg C ha-1 in shrubs in the study sites. Carbon stock in standing floor litters ranged from 5.83-25.44 Mg C ha-1. Soil carbon stock was significantly higher (F 2, 27 (0.05) = 295.61; P = 4.39×10-19) in the Tectona grandis plantation compared to other vegetations. Contributions of C stock is in the order of soil > standing floor litter > Shrubs >herbs.