ABSTRACT

The use of diameter at breast height (DBH) measurement in allometric equations for estimation of biomass (AGB) requires that measurements be taken precisely at 130cm from the ground level. However, obtaining this measurement is not always possible. This study aimed to i) investigate the relationship between the DBH and diameters measured at different heights below 130 cm on tree stems, ii) develop an equation for converting diameters measured below 130cm to DBH, and iii) evaluate the accuracy of using converted DBH values to estimate the AGB. We measured the diameters of 376 trees at various stem heights at intervals of 25 cm up to the DBH, in a protected area of the Atlantic Forest, Brazil. Three theoretical models were applied and tested, and the best equation was selected. The relationships between DBH and diameters at 50, 75, and 100 cm did not differ, which allowed the use of one general equation for converting these diameters to DBH. Measurements taken below 50 cm may lead to biased estimations; thus, we propose two additional equations for estimating DBH from these heights. The DBH converted from diameters measured at other heights can be accurately used to estimate the tree AGB and carbon stocks.

摘要

在异速生长方程中使用胸高直径 (DBH) 测量来估算生物量 (AGB) 需要在距离地面 130 厘米处进行精确测量。然而，并非总能获得此测量值。本研究旨在 i) 调查 DBH 与在树干 130 cm 以下不同高度测量的直径之间的关系，ii) 开发一个将 130 cm 以下测量的直径转换为 ​​DBH 的方程式，以及 iii) 评估使用转换后的 DBH 值的准确性估计 AGB。我们在巴西大西洋森林的保护区内测量了 376 棵树的直径，这些树的树干高度各不相同，以 25 厘米的间隔达到胸径。应用和测试了三个理论模型，并选择了最佳方程。50、75、50、75时胸径与直径的关系 和 100 cm 没有区别，这允许使用一个通用方程将这些直径转换为 ​​DBH。在 50 厘米以下进行的测量可能会导致估计有偏差；因此，我们提出了两个额外的方程来从这些高度估算 DBH。从其他高度测量的直径转换的胸径可以准确地用于估计树木的 AGB 和碳储量。