Image analysis procedure for the optical scanning of fine-root dynamics: errors depending on the observer and root-viewing window size
Image analysis procedure for the optical scanning of fine-root dynamics: errors depending on the observer and root-viewing window size
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DOI：
10.1093/treephys/tpy124
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发表时间：
2018-12-01
期刊：
影响因子：
4
通讯作者：
Ikeno, Hidetoshi
中科院分区：
文献类型：
--
作者：
Kume, Tomonori;Ohashi, Mizue;Ikeno, Hidetoshi
明确细根的动态是理解森林生态系统碳和养分循环的关键。光学扫描仪可用于研究森林生态系统的细根动态。本研究检查了适合具有大（210 mm x 297 mm）根观察窗口的光学扫描仪的图像分析程序。我们提出了一种方案，用于分析由光学扫描仪获得的覆盖深度为0-210 mm的全土壤图像。我们使用六位具有不同研究根经验的观察者来测试我们的方案。观测者根据该方案从婆罗洲热带森林记录的连续土壤图像的人工数字化中获得数据。此外，该研究在一个简单的练习中检验了土壤图像大小和细根动力学估计准确性之间的潜在权衡。6名观察员学习了该方案，并获得了相似的细根生长和生物量的时间模式，无论他们的经验如何，误差都在10-20%之间。但由于分解细根的能见度较低，分解误差较大。这个简单的练习表明，较小的根观察窗口（小于原始窗口的60%）产生的细根动态模式与原始窗口大小不同。该研究表明，我们的图像分析方法对光学扫描仪拍摄的全土壤图像在估计森林生态系统细根动态方面具有很高的适用性。
Clarifying the dynamics of fine roots is critical to understanding carbon and nutrient cycling in forest ecosystems. An optical scanner can potentially be used in studying fine-root dynamics in forest ecosystems. The present study examined image analysis procedures suitable for an optical scanner having a large (210 mm x 297 mm) root-viewing window. We proposed a protocol for analyzing whole soil images obtained by an optical scanner that cover depths of 0-210 mm. We tested our protocol using six observers with different experience in studying roots. The observers obtained data from the manual digitization of sequential soil images recorded for a Bornean tropical forest according to the protocol. Additionally, the study examined the potential tradeoff between the soil image size and accuracy of estimates of fine-root dynamics in a simple exercise. The six observers learned the protocol and obtained similar temporal patterns of fine-root growth and biomass with error of 10-20% regardless of their experience. However, there were large errors in decomposition owing to the low visibility of decomposed fine roots. The simple exercise revealed that a smaller root-viewing window (smaller than 60% of the original window) produces patterns of fine-root dynamics that are different from those for the original window size. The study showed the high applicability of our image analysis approach for whole soil images taken by optical scanners in estimating the fine-root dynamics of forest ecosystems.