Purpose of Review

We provide a comprehensive review of the empirical and modelling approaches used to quantify the radiation–vegetation interactions related to vegetation temperature, leaf optical properties linked to pigment absorption and chlorophyll fluorescence emission, and of their capability to monitor vegetation health. Part 1 provides an overview of the main physiological indicators (PIs) applied in remote sensing to detect alterations in plant functioning linked to vegetation diseases and decline processes. Part 2 reviews the recent advances in the development of quantitative methods to assess PI through hyperspectral and thermal images.

Recent Findings

In recent years, the availability of high-resolution hyperspectral and thermal images has increased due to the extraordinary progress made in sensor technology, including the miniaturization of advanced cameras designed for unmanned aerial vehicle (UAV) systems and lightweight aircrafts. This technological revolution has contributed to the wider use of hyperspectral imaging sensors by the scientific community and industry; it has led to better modelling and understanding of the sensitivity of different ranges of the electromagnetic spectrum to detect biophysical alterations used as early warning indicators of vegetation health.

Summary

The review deals with the capability of PIs such as vegetation temperature, chlorophyll fluorescence, photosynthetic energy downregulation and photosynthetic pigments detected through remote sensing to monitor the early responses of plants to different stressors. Various methods for the detection of PI alterations have recently been proposed and validated to monitor vegetation health. The greatest challenges for the remote sensing community today are (i) the availability of high spatial, spectral and temporal resolution image data; (ii) the empirical validation of radiation–vegetation interactions; (iii) the upscaling of physiological alterations from the leaf to the canopy, mainly in complex heterogeneous vegetation landscapes; and (iv) the temporal dynamics of the PIs and the interaction between physiological changes.

中文翻译：

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高分辨率高光谱和热成像对植被健康的早期诊断：经验关系和辐射传输建模的经验教训

审查目的

我们对用于量化与植被温度，与色素吸收和叶绿素荧光发射有关的叶片光学特性的辐射-植被相互作用的经验和建模方法及其监测植被健康的能力进行了全面综述。第1部分概述了应用于遥感的主要生理指标（PI），以检测与植被疾病和衰退过程相关的植物功能的变化。第2部分回顾了通过高光谱和热图像评估PI的定量方法开发的最新进展。

最近的发现

近年来，由于传感器技术取得了非凡的进步，包括为无人飞行器（UAV）系统和轻型飞机设计的先进相机的小型化，高分辨率高光谱和热图像的可用性得到了提高。这项技术革命促使科学界和工业界广泛使用高光谱成像传感器；它有助于更​​好地建模和理解电磁波谱不同范围的敏感性，以检测用作植被健康预警指标的生物物理变化。

概要

审查涉及PIs的能力，如植被温度，叶绿素荧光，光合能量下调和通过遥感检测到的光合色素，以监测植物对不同胁迫的早期反应。最近已经提出了多种检测PI变化的方法，并已通过各种方法来监测植被健康。今天，遥感界面临的最大挑战是：（i）高空间，光谱和时间分辨率图像数据的可用性；（ii）辐射-植被相互作用的经验验证；（iii）从叶到冠层的生理变化增加，主要是在复杂的异质植被景观中；（iv）PI的时间动态以及生理变化之间的相互作用。