Development of volume equations for teak plantation in Nimbia Forest Reserve in Nigeria using Dbh and height

Abstract

Volume equations were developed for teak (Tectona grandis (Linn. f.)) plantation in Nimbia Forest Reserve using diameter at breast height (Dbh) and merchantable height as independent variables. Data were collected from 10 sampled plots of 20m x 20m each. The number of trees per plot ranged from 21 to 43 with a total of 364 trees. The mean Dbh and height were 13.58cm and 5.50m, respectively. Three different models were obtained through regression analyses (multiple linear, simple linear and double log form) which were ranked 1^st, 2^nd and 3^rd. Adjusted coefficient of determination (Adjusted R²) and root mean square error (RMSE) were used to rank the developed models. Log-transformed values yielded better results compared with the untransformed values. The resulting equations were tested for validation with processed data obtained from independent additional plots and were found to be desirable for estimating the merchantable volume for teak in Nimbia Forest Reserve, Nigeria.