Abstract: In order to establish the one-way and two-way tree volume models for Gansu province and improve their accuracy, the paper took Prunu sarmeniaca and Aspen as the research object and applied electronic theodolite to obtain precise data of standing tree in a nondestructive way. By using simultaneous equation of error variance, double-element tree volume equation NDBH duality standing tree volume equation and tree height diameter model were constructed, which provided scientific basis for the estimation of forest stock volume in relevant tree species. The compatibility of the standing tree volume equation was derived from the classic Yamamoto and Tibetan two-way tree volume models as well as index tree height model, followed by an overall evaluation of the newly-established model with six indexs. It was revealed by the result that both two-way tree volume models could yield good results. The average prediction error of two-way tree volume table and prunusarmeniaca DBH unitary-volume table is 2. 12% and2. 58% respectively. In terms of aspen binary volume table and DBH unitary volume table,the average prediction error is 1. 57% and 2. 01% respectively. Therefore ,the models of this article can be used to estimate the volume of prunusarmeniaca and aspen in Gansu Province.

Key words: Two-way Tree Volume, One-way Tree Volume Model, Tree Hight Model, error variable simultaneous equations, Compatibility, Prunu sarmeniaca, Aspen