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

Abstract

The form-factor for the stem surface area is directly proportional to the square root of the form-factor for the stem volume, i.e., the square root law of the form-factor. Although the square root law addresses the stems of coniferous trees, the nature of the proportional coefficient of the law has not been discussed. In this study, we demonstrated that the coefficient indicates the stem taper; therefore, it is named “Taper Index based on Form-Factor (TIFF).” We also examined the relationship between the form-factor for the culm surface area and the form-factor for the apparent culm volume of 570 culms across three bamboo species (Phyllostachys pubescens Mazel ex Houz., P. bambusoides Sieb. et Zucc., and P. nigra var. henonis). The square root law held true for all three bamboo species. The species-specific TIFF was determined to be 0.873 for P. pubescens, 0.897 for P. bambusoides, and 0.901 for P. nigra. This result implied that P. pubescens had a more tapering culm form compared to the other two species, while culm taper was similar between P. bambusoides and P. nigra. Our findings align with empirical observations of the culm taper of the bamboo species. Intra-species variation in TIFF was considerably small, allowing us to evaluate the species-specific culm taper from a small number of samples. Therefore, we conclude that TIFF provides a simple and useful method for quantifying species-specific culm or stem taper, and facilitates the estimation of merchantable or total volume.

Plasticity in the Morphology of Growing Bamboo: A Bayesian Analysis of Exogenous Treatment Effects on Plant Height, Internode Length, and Internode Numbers

“…Our results showed that the distribution of internode length in P. edulis had distinct features: gradually increasing from the bottom, peaking near the 25th-30th internode, then gradually getting shorter again, showing a shape similar to a Gaussian distribution (Figure 3). These results are in accord with those of recent studies [65], which indicated that the diameter of the internodes gradually decreases from the bottom to the top, becoming extremely thin at the tip; the culm shape is similar to a cone [68,74,75]. P. edulis is generally taller than 10 m, and some individuals reach about 20 m [70][71][72][73]76].…”

“…Our results show that both Suc and GA had a significant positive effect on the plant height; Suc had a stronger effect on internode number compared with GA, while GA had a stronger effect on internode length than Suc. In addition, we did not find the greater number of internodes (75) or higher plant height (21.0 m) of P. edulis that were published previously [63,[65][66][67][68][69][70][71][72][73][74]. Here, the characteristics of the culm structure, the promoting effects of the exogenous Suc and GA on the plant height, internode length, and internode number, the variation in the effect of exogenous treatment with distance, and the ecological benefits brought by increased plant height are discussed.…”

Análise do efeito do espaçamento e material genético na forma do tronco de árvores de >i<Eucalyptus>/i< spp. sob o prisma da modelagem

“…A maneira mais simples e menos usual de determinar a forma a partir do conceito de taper é a partir de um modelo fenomenológico que possui um parâmetro exclusivo de forma. Este modelo proposto por Kunze (1873) apud Inoue et al (2021) associa o raio da seção do tronco (y) em função da distância da seção até a altura total (H − h i ). Possui duas constantes que indicam o afilamento da espécie (α) e outra o expoente de forma (β):…”