科研之友
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摘要
the development of a compatible taper-volume system is presented for estimating volume without bark of pinus cooperi blanco. the system was based on a polynomial linear model previously used in durango, m谷xico, and modified as a function of the data to add flexibility. the model of total volume obtained from the system approximates in its structure the total volume model of schumacher and hall. the equations were adjusted as a completely simultaneous system to compensate for the variation between taper and accumulated marketing volume, which occurs at any point of the bole. the structure includes mixed effects (me) to control the variability due to the tree, correct heterocedasticity and to obtain precise predictions in trees of high commercial value. the additional information provided by the structure of me noticeably improves the predictive capacity in the lower part of the bole. in addition, the simultaneous fit of the taper-volume system by means of me reduces the standard errors of the estimators of the parameters.
