The simultaneous equations models for the application in forestry

摘要

In accordance with weakness of traditional biomass models in which the sum of the above- and below-ground tree components was not equal to the whole tree, compatible biomass equations were developed for the above- and below-ground tree components of 11 kinds of tree species in Heilongjiang Province. The data used to develop biomass models are from 299 trees that were collected from 69 sample plots, and represented a wide range of stand and site conditions in Heilongjiang Province. Based on the total biomass model as restrictions, the compatible tree biomass equations for each component (stems, branches, foliages, and roots) were separately established by considering diameter at breast height (D) as independent variables in the form of simultaneous equations with measure error of independent variables. The evaluation and validation procedures for tree biomass models were performed by using the following statistical criterions: the coefficient of determination (R2), sum square of error (SEE), Mean Bias (MB), and Mean Absolute Bias (MAB). The results showed that although parameter estimation accuracy of compatible biomass equations was not better than traditional biomass models, the compatible biomass equations could effectively overcome the weakness of un-compatible of traditional biomass models.