Deriving a reduction factor for woody part of culm for bamboo Phyllostachys pubescens

Abstract

We determined the reduction factor for the woody part of culm for one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houz. The determined reduction factor enables us to convert the cross-sectional area of the whole culm into that of the culm wall. We collected 650 cross-cutting sample culms from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan. For the cut-end surface, the external culm diameter and culm wall thickness were measured, and then the cross-sectional area of the whole culm and the culm wall were computed. The cross-sectional area of the culm wall was strongly correlated with that of the whole culm. The regression analysis between these cross-sectional area indicated that the reduction factor for P. pubescens was 0.311, independent of the magnitude of the cross-sectional area. The independence implied that the determined reduction factor could be directly applied to convert the apparent culm volume into wood volume. Implications of the reduction factor for estimating transpiration and carbon stock of P. pubescens stands were discussed. The Monte Carlo simulation revealed that at least, but not more than, 60-70 cross-cutting culms collected from 20 culms are necessary for the reduction factor when estimating the stand level transpiration and carbon stock.

Derivation of two-way volume equation for bamboo, Phyllostachys pubescens

“…21 is designed to estimate the apparent culm volume, to estimate the wood volume there is a need for a reduction factor for converting the apparent culm volume into the wood volume. For P. pubescens, Inoue et al (2011) found that the ratio of the cross-sectional area of whole culm to that of the culm wall is 0.311, independent of the magnitude of the cross-sectional area. For this reason, Inoue et al (2011) concluded that the reduction factor for converting the apparent culm volume into the wood volume is estimated to be 0.311.…”

“…For P. pubescens, Inoue et al (2011) found that the ratio of the cross-sectional area of whole culm to that of the culm wall is 0.311, independent of the magnitude of the cross-sectional area. For this reason, Inoue et al (2011) concluded that the reduction factor for converting the apparent culm volume into the wood volume is estimated to be 0.311. By multiplying the apparent culm volume estimated with Eq.…”

“…The replacement of natural or plantation forests by bamboo forests can change the terrestrial water cycle (Onozawa et al 2009a, b;Shinohara et al 2010). Moreover, such range expansion of P. pubescens stands may have effects on carbon storage and decomposition in forest ecosystems (Inoue and Suga 2009;Inoue et al 2011).…”

Self-adaptive formation of uneven node spacings in wild bamboo

“…It was found in Ref. [43] that for moso bamboos, the cross-sectional area of the whole culm S and that of the culm wall S w are related by (see Fig. 6)…”

“…[45], and that of ε was given in Ref. [43]. The value of η has been newly deduced from our database; the method of derivation is described in detail in Appendix B.…”