The study involved estimating stem volume, calculating merchantable vo lume yielding rate and timber assortments volume with four-parameter cylinder- vo lume-ratio stem profile. The result shows it performs better than Schumarher-H all at estimating stem volume when the data from Quercus aliena we re classified by cla ss. Compared with taper function at calculating merchantable volume yielding rat e, four-parameter cylinder-volume-ratio stem profile also performs well with sys tematic error below 1% and mean square error below 5%. To Pinus tabu laeformis tr ees, taper function has better accuracy degree than cylinder-volume-rati o method , but the result is contrary to Q.aliena. When calculating t imber assortments vo lume with four-parameter cylinder-volume-ratio method, systematic error is be low 6% and mean square error below 19%.
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