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

Abstract

It is strongly debated whether bamboo forest ecosystems are a carbon sink or a carbon source because of insufficient knowledge regarding carbon loss via CO 2 emissions from these forests. The surface area (S) of bamboo culms (stems) is important for estimating culm respiration, a major component of carbon cycling in bamboo forests. However, few studies have attempted to formulate predictive equations for S. In this study, we developed allometric equations for predicting S in three bamboo species grown in Kyushu Island, western Japan: Phyllostachys pubescens Mazel ex Houz., P. bambusoides Sieb. et Zucc. and P. nigra var. henonis. We used a power equation between S and diameter at breast height (D) and a linear equation between S and D × total culm length (H). The results indicated that P. bambusoides and P. nigra shared common site-independent equations. In contrast, P. pubescens required species-specific equations due to interspecific variation in culm slenderness and tapering. We also found that D was a better predictive variable than DH when quantifying S because of its satisfactory predictive performance and simplicity. These findings will be beneficial for evaluating the contribution of bamboo forest ecosystems to carbon cycling.

A new taper index based on form-factor: application to three bamboo species (Phyllostachys spp.)

“…The diameters were measured in two orthogonal directions, and the average was used in our analysis. Note that the data was previously used in another study (Inoue et al 2011b(Inoue et al , 2012(Inoue et al , 2013(Inoue et al , 2018Inoue and Suga 2009;Shima et al 2016;Suga et al 2011). A general description of the sample culms is provided in Table 1.…”

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).…”

“…The difference in the slope of α in Equation (1) is produced by the difference in stem tapering, whereas the difference in the slope of β in Equation. (2) is caused by the differences in stem slenderness and tapering (Inoue 2004;Inoue et al 2018). The generality of the slope in Equation 1as discussed above implies the small variation in the stem tapering among the coniferous trees.…”

“…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).…”

“…The cone assumption model enables us to compute S from D (or diameter at base) and H geometrically by assuming that the stem form is a cone (e.g., Gavrikov 2014Gavrikov , 2015bKatayama et al 2019;Zhao et al 2019). In contrast, several scientists have proposed regression models for predicting S (e.g., Lexen 1943;Carron 1968;Swank and Schreuder 1974;Inoue 2004;Inoue et al 2018). The relationship between S and the product of D and H for Pinus ponderosa could be expressed by the following regression equation:…”