Using fibre-optic sensing for non-invasive, continuous dendrometry of mature tree trunks

Dendrometry is the main non-invasive macroscopic technique commonly used in plant physiology and ecophysysiology studies. Over the years several types of dendrometric techniques have been developed, each with their respective strengths and drawbacks. Automatic and continuous monitoring solutions are being developed, but are still limited, particularly for non-invasive monitoring of large-diameter trunks. In this study, we propose a new type of automated dendrometer based on distributed fibre-optic sensing that continuously measures the change in stem circumference, is non-invasive, and has no upper limit on the trunk diameter on which it can be installed. We perform a three-month validation experiment during which we deploy a fibre-optic cable at three localities around the trunks of two specimens of Brachychiton. We verify the accuracy of this new method through comparison against a conventional point-dendrometer, and we observe a consistent time lag between the various measurement locations that varies with the meteorological conditions. Finally, we discuss the feasibility of the fibre-based dendrometer in the context of existing dendrometric techniques and practical experimental considerations.This repository contains the data and scripts to reproduce the results from this study. Please refer to README.md to get started.树木测径术（Dendrometry）是植物生理学与生态生理学研究中常用的主流非侵入式宏观观测技术。多年来，学界已开发出多类树木测径技术，各类技术均具备各自的优势与局限。当前虽已推进自动化连续监测方案的研发，但此类方案仍存在诸多局限，针对大直径树干的非侵入式监测场景尤为受限。本研究提出一种基于分布式光纤传感（distributed fibre-optic sensing）的新型自动测径仪，该仪器可连续监测茎秆周长变化，具备非侵入式特性，且对安装所用树干的直径无上限限制。我们开展了为期三个月的验证实验，在两株瓶树属（Brachychiton）植物的树干周围三处位置布设了光纤线缆。通过与传统点位式测径仪（point-dendrometer）开展对比实验，我们验证了该新型测径方法的精度，并观测到不同测量点位间存在稳定的时间延迟，且该延迟随气象条件变化而发生改变。最后，我们结合现有树木测径技术体系与实际实验考量，探讨了该光纤式测径仪的应用可行性。本代码仓库包含可复现本研究结果的实验数据与运行脚本，请参阅README.md以完成上手操作。