Volume equations for poplars growing on farmland in Sweden.

摘要

The aim of the study was to construct a simple volume equation for poplar and to evaluate the equation together with seven published equations. Data from 72 poplars were collected from 37 stands in central and southern Sweden (lat. 55-60 degrees N). The stands' mean age and density was 21 years and 940 stems ha-1, respectively and the trees' mean diameter at breast height (DBH) was 25 cm. One simple volume equation with three parameters to be estimated for poplar was constructed with DBH and total height (H) as independent variables. This equation was analyzed and compared to seven published simple equations. The best performance, in terms of low values of Root Mean Square Error (RMSE) and Absolute Bias, was achieved by the equations developed by Eriksson and by Scott. However, due to these equations high level of multicollinearity an alternative recommendation was made where the constructed equation is recommended.