Estimation of bole biomass and carbon stocks through three volume equations for tree species in Ogba zoo, Nigeria

Abstract

Precise and accurate estimates of bole Carbon Stocks (CS) sequestration are crucial for sustainable forest management related to climate change. Therefore, the study is aimed at estimating CS through three volume equations techniques with a view to identify how CS sequestration varies across volume equation. A total of ten (10) Temporary Sample Plots (TSPs) of 20m x 20m (0.04ha) in size were randomly laid in the study site. Tree species in all of the TSPs with a diameter ≥ 10 were measured for diameters and heights. Data were analysed using descriptive statistics, volume equations, regression and analysis of variance at α0.05. A total of twenty five (25) tree species comprising of fourteen (14) families were found in the TSPs from hundred and one (101) individual trees. There were differences in CS with respect to the three volume equations. There were very strong linear relationship between CS and the three volume equations with R² value > 90%. There was statistical difference amongst Hossfeld’s equation, Geometric equation for the truncated cone and Smalian’s equation with t-Test value of 0.01, while Geometric equation for the truncated cone showed statistical difference with Hossfeld’s equation with t-Test value of 0.00. There was no statistical difference between Smalian’s equation and Geometric equation for the truncated cone with t-Test value of 0.57. Therefore, the scatter plots shows that the three bole volume equations are good predictors for estimating CS. However, Geometric equation for the truncated cone and Smalian’s equation had a high standard error and uncertainty values of 5%, 143% and 6%, 145%.

Keywords: carbon stocks, carbon dioxide equivalent, volume equation, tree species, Ogba Zoo