Purpose of Review

The successful application of thermal infrared (TIR) remote sensing in the agricultural domain, largely driven by the arrival of new platforms and sensors that substantially increased thermal data resolution and availability, has sparked interest in thermography as a tool for monitoring forest health. In this review, we take a step back to reflect on what physiological responses are reflected in leaf and canopy temperature and summarise research activities on TIR remote sensing of stress responses in forest environments, highlighting current methodological challenges, open questions, and promising opportunities.

Recent Findings

This systematic literature review showed that whilst the focus still remains on satellite imagery, Uncrewed Aerial Vehicles (UAVs) are playing an increasingly important role in testing the capabilities and sensitivity to stress onset at the individual tree level. To date, drought stress has been the focal point of research, largely due to its direct link to stomatal functioning at leaf level. Though, research into thermal responses to other stressors, e.g. pathogens, is also gaining momentum.

Summary

Disentangling stress-induced canopy temperature variations from environmental factors and structural influences remains the main challenge for broader application of TIR remote sensing. Further development and testing of approaches for thermal data analysis, including their applicability for different tree species and sensitivity under different climatic conditions, are required to establish how TIR remote sensing can best complement existing forest health monitoring approaches.

中文翻译：

---

森林环境胁迫响应的热红外遥感：发展、挑战和机遇回顾

审查目的

热红外（TIR）遥感在农业领域的成功应用，很大程度上是由于新平台和传感器的出现，大大提高了热数据分辨率和可用性，引发了人们对热成像作为监测森林健康的工具的兴趣。在这篇综述中，我们退后一步思考叶子和冠层温度反映了哪些生理反应，并总结了森林环境胁迫反应 TIR 遥感的研究活动，强调了当前的方法挑战、悬而未决的问题和有希望的机会。

最近的发现

这项系统的文献综述表明，虽然焦点仍然集中在卫星图像上，但无人驾驶飞行器（UAV）在测试单棵树水平上对压力发生的能力和敏感性方面发挥着越来越重要的作用。迄今为止，干旱胁迫一直是研究的焦点，这主要是因为它与叶层气孔功能的直接联系。不过，对其他应激源（例如病原体）的热反应的研究也正在蓬勃发展。

概括

将应力引起的冠层温度变化与环境因素和结构影响分开仍然是 TIR 遥感更广泛应用的主要挑战。需要进一步开发和测试热数据分析方法，包括它们对不同树种的适用性和不同气候条件下的敏感性，以确定 TIR 遥感如何最好地补充现有的森林健康监测方法。