Digital Approach for Measuring Tree Diameters in the Amazon Forest

ABSTRACT Buttresses and other natural structures modify the shape of stems in Amazonia and change the diameter at breast height (DBH) measured at 1.3 m at ground level. The lack of adequate measurement techniques affects negatively forest dynamics analyses and biomass estimating. The study evaluated an indirect method of measuring diameters in trees with DBH > 40 cm using principles of digital photogrammetry. The results obtained with two cameras (smartphone and Sony) were compared with direct measurements using diametric tape and a ladder. The technique is adequate to measure the diameters of trees with measurement point above 2 m of ground, with a confidence interval of ±1cm. The use of photogrammetry as a supplementary tool to the diametric tape (IC ± 0.24 cm) is recommended, helping to measure trees with diameter above the reach of the technician in forest inventories.

摘要：亚马孙地区的板状根（Buttresses）及其他天然结构会改变树干形态，进而影响距地面1.3米处测得的胸高直径（DBH）数值。适配的测量技术缺失，会对森林动态分析与生物量估算造成负面影响。本研究基于数字摄影测量原理，针对胸高直径大于40厘米的林木，评估了一种间接测径方法。研究将使用智能手机与索尼（Sony）两款相机获取的测量结果，与采用测径尺及梯子开展的直接测量结果进行了对比。结果显示，该技术可适用于测量离地高度超过2米的林木胸径，测量置信区间为±1厘米。建议将摄影测量技术作为测径尺的辅助工具（置信区间±0.24厘米），可辅助完成林业调查中技术人员无法触及的林木直径测量工作。