On the geometry and allometry of big-buttressed trees - a challenge for forest monitoring: new insights from 3D-modeling with terrestrial laser scanning
On the geometry and allometry of big-buttressed trees - a challenge for forest monitoring: new insights from 3D-modeling with terrestrial laser scanning
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DOI：
10.3832/ifor1449-007
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
Nils Nölke;L. Fehrmann;S. J. I. Nengah;T. Tiryana;D. Seidel;C. Kleinn
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文献类型：
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作者：
Nils Nölke;L. Fehrmann;S. J. I. Nengah;T. Tiryana;D. Seidel;C. Kleinn
摘要：在许多古老的天然和接近天然的森林类型中，特别是在潮湿的热带森林中，相对少量的很高的树木对林分断面积和生物量的贡献很大。此类树木通常具有明显的板状根，具有不规则的非凸形状。扶壁是最低茎部分的复杂结构，大多数树木生物量都位于此处。用于评估扶壁树直径的方法对体积和生物量的确定以及对热带森林地上碳储量的估计有很大影响。由于在这种情况下测量胸高直径（1.3 m 处的 DBH）是不可行的，因此通常测量支柱上方的直径（DAB），即树的圆柱形树干开始的位置，并将其作为自变量包含在生物量模型中。我们进行了一项方法学研究，旨在通过应用地面激光扫描（TLS）来确定属于几种热带物种的单根支撑树的体积和生物量。分析了扶壁的几何形状和异速生长，以及扶壁体积和横截面积沿茎高度的变化。我们的结果表明，DAB 高度的横截面积 (ADAB) 与在 1.3 m 高度测量的实际树木断面积之间的关系相对较强 (R² = 0.87)，在一系列不同的树种、板垛形态和树木尺寸中。此外，茎横截面积随树高的变化惊人地相似且平滑。尽管采样的树木数量很少，但本研究中使用的方法为扶壁树的非常不规则的几何形状提供了新的见解。我们的结果可能有助于改进支撑树的体积和生物量模型，支撑树是热带森林碳储量的重要贡献者。
Abstract: In many old-growth natural and close-to-natural forest types, notably in humid tropical forests, a relatively small number of very tall trees contribute considerably to stand basal area and biomass. Such trees often show distinct buttress roots with irregular non-convex shapes. Buttresses are complex structures in the lowest stem section, where most tree biomass is located. The methods used to assess the diameter of buttressed trees have a large impact on the determination of volume and biomass, as well as on the resulting estimates of the aboveground carbon stock in tropical forests. As the measurement of diameter at breast height (DBH at 1.3 m) is not feasible in such conditions, the diameter above buttress (DAB), where the cylindrical bole of the tree begins, is usually measured and included as an independent variable in biomass models. We conducted a methodological study aimed at determining the volume and biomass of individual buttressed trees belonging to several tropical species by the application of terrestrial laser scanning (TLS). The geometry and allometry of the buttresses, as well as the change with height along the stem in buttress volume and cross-sectional area were analyzed. Our results suggest that the relationship between cross-sectional areas at DAB height (ADAB) and the actual tree basal area measured at 1.3 m height is relatively strong (R² = 0.87) across a range of different species, buttress morphologies and tree dimensions. Furthermore, the change in stem cross-sectional area with tree height was surprisingly similar and smooth. Despite the small number of trees sampled, the methodological approach used in this study provided new insights on the very irregular geometry of buttressed trees. Our results may help improving the volume and biomass models for buttressed trees, that are crucial contributors to carbon stocks in tropical forests.