ARTIFICIAL NEURAL NETWORK MODELLING OF ABOVEGROUND BIOMASS FROM TROPICAL RAIN FORESTS IN NIGERIA

Abstract

This study investigated the impact of applying artificial neural networks (ANNs) with different input variables and different architectures to estimate aboveground biomass (AGB) using allometric data from tropical forests in Southwestern Nigeria. The study also compared the result of ANNs with linear regression. Three fully connected feed-forward neural networks (all four-layer) with backpropagation of error were used in this study. They had two hidden layers: the first two had topography [2, 3, 3, 1], and the third had topography [3, 5, 5, 1]. Rectified Linear Unit (ReLU) activation function was used for all networks; Mean Squared Error (MSE) was used as the loss function. A learning rate of 1e-06 and 1000 iterations was used to run the first two ANNs, and a learning rate of 1e-06 and 1850 iterations was used to run the third. Maximum loss for each neural network was 12.8393, 12.0371, and 0.2078, respectively, while minimum loss was 0.0391, 0.0408, and 0.1559, respectively. Accuracy was measured using Root Mean Squared Error (RMSE) with the training for each neural network RMSE’s being 0.1997, 0.2113 and 0.3949 while test RMSE’s was 0.2199, 0.2284, and 0.3812 for each neural network. &nbsp