A Newly Built Model of an Additive Stem Taper System with Total Disaggregation Model Structure for Dahurian Larch in Northeast China

Yanli Xu,Lichun Jiang,Muhammad Khurram Shahzad

doi:10.3390/f12101302

Yanli Xu, Lichun Jiang + Show 1 more

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https://doi.org/10.3390/f12101302

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Abstract

Stem taper function is an important concept in forest growth and yield modeling, and forest management. However, the additivity of the function and the inherent correlations between stem components (diameter outside bark—dob, diameter inside bark—dib, and double-bark thickness—dbt) are seldom considered. In this paper, a total disaggregation model (TDM) structure was developed based on the well-known Kozak (2004) model to ensure the additivity of the stem components. The reconstructed model was fitted with the data of 1281 felled Dahurian larch trees from three regions of Daxing’anling Mountains in Northeast China. The results from TDM were compared with other additive model structures including adjustment in proportion (AP), non-additive taper models (NAM), and three logical structures of NSUR (AMO, SMI, SMB). The results showed that the difference was significant among the three regions. The performance of TDM was slightly better than those of other model structures. Therefore, TDM was considered as another optimal additive system to estimate stem, bark thickness, and volume predicting for Dahurian larch in Northeast China besides NSUR, a method widely used in calculating additive volume or biomass throughout the world. We believe this work is cutting-edge, and that this methodology can be applied to other tree species.

Highlights

The diameter outside bark, inside bark, and bark thickness are crucial measurements in forestry
Dib is used to calculate the wood volume of logs and trees, and is usually measured by subtracting the bark thickness from the dob, whose accuracy mainly depends on the precise estimation of the bark thickness and dob
We introduced a dummy variable r to account for stem taper difference of three regions (i.e., r1 = 1 and r2 = 0 for region one; r1 = 0 and r2 = 1 for region two; r1 = 0 and r2 = 0 for region three)

Summary

Introduction

The diameter outside bark (dob), inside bark (dib), and bark thickness are crucial measurements in forestry. Dib is used to calculate the wood volume of logs and trees, and is usually measured by subtracting the bark thickness from the dob, whose accuracy mainly depends on the precise estimation of the bark thickness and dob. Incorrect estimation of bark thickness may lead to an inaccurate estimation of bark volume and stand volume in forest inventory, increment study or the log trade [1]. The utility of bark has transformed from unnecessary residue to high-value biomass energy [6]. The value of bark volume has been growing progressively, as it can be used to estimate biomass and quantify carbon stocks [7]. New bark thickness models are being developed, and their importance has been gradually recognized by forestry scholars

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