Comparing the methods for quantifying the culm surface area of bamboo, Phyllostachys pubescens

Abstract

We compared several methods for quantifying the culm surface area (S) of one of the most common bamboos in Japan, Phyllostachys pubescens Mazel ex Houz. Nine sample culms of P. pubescens were felled, and the true S was determined by the fine resolution analysis of the culm form (SFRA). The S was then calculated independently with the sectional measurement method from the successive diameters measured at equal intervals of one‐twentieth (S20), one‐tenth (S10), one‐fifth (S5) and one‐half (S2) of the total culm length. The S was also quantified geometrically from the total culm length and the diameter at breast height or at base by assuming that the culm form could be approximated by a cone (SDBH and SDAB). The SFRA was compared with each of the computed S values. For S10, S5 and S2, both the mean relative bias (%BIAS) and relative root mean square error (%RMSE) decreased with an increase in the number of measured diameters. The %BIAS and %RMSE of the S10 were, respectively, comparable and smaller compared to those of S20. The bias of the SDBH and SDAB suggested that the cone assumption of the culm form was violated. In conclusion, we recommend that the S should be quantified from the successive diameters measured at equal intervals of one‐tenth of the total culm length using the sectional measurement method.

Allometric Equations for Predicting Culm Surface Area of Three Bamboo Species (Phyllostachys spp.)

“…For all culm samples, S was calculated from H and successive diameters measured at one-tenth intervals of H using the sectional measurement method [25,39]. Similarly, apparent culm volume (V) [52,53] was computed with the same method [33][34][35][36].…”

“…Total culm length (H) and external culm diameter at breast height (D) were directly measured with a tape measure to the nearest 0.1 m and a digital caliper to the nearest 0.1 cm, respectively. To quantify S accurately and efficiently, external culm diameters at 10 successive points were measured with a caliper to the nearest 0.1 cm [25]. The measurement points were located along the culm at equal intervals of one tenth of the direct measured H. It should be noted that the ages of sample culms were not recorded in our sampling.…”

“…By contrast, previous studies have not focused on the quantification of S. A previous study assumed cone geometry for culms when estimating R C in a bamboo forest [19]. However, this simplistic assumption is violated when quantifying S [25]. Because small errors in S could lead to large errors in scaled-up R C [24], S must be characterized accurately and precisely.…”

Comparison of models for estimating stem surface area of coniferous trees grown in old-growth natural forests

“…First, S of each sample tree was computed using the sectional measurement method (Inoue and Sakamoto 2017;Inoue et al 2018). Second, Equations (1) and (2) were fitted to the relationships of S to DH and G, respectively (Inoue 2004).…”

“…A direct measurement of S of standing trees is difficult (Inoue 2004). The most reliable measurement method is destructive sampling as follows: 1) The target tree is felled at ground level and all branches are cut from the stem; 2) The stem diameters are directly measured at a dozen points along the stem; and 3) S is calculated by the sectional measurement method (Inoue and Sakamoto 2017;Inoue et al 2018) or the integration of stem taper equation (Inoue 2004(Inoue , 2006. Such destructive sampling is, however, time-consuming and labor-intensive (Inoue et al 2018).…”