Construction and validation of tree volume equations for Eucalyptus saligna in Cameroon

Eight volume equations were compared based on fit and validation statistics using data collected from Eucalyptus saligna stands in Cameroon. Results obtained indicate that an equation may fit very well to a data set, but may not necessarily be the best when it comes to predictions using an independent data set collected from the same population. The contrasting results obtained between model fitting and model validation go strongly to support the need for model validation, often neglected, as a crucial step in model building process in order to avoid wrong choices. Validation helps to build some confidence when using the model and can also help in identifying some deficiencies inherent in the model that require some revision. The Schumacher and Hall (1933) equation and the Combined Variable equation (Spurr 1952) gave the best results and recommendations have been made on their usage.