Monitoring growth, establishment, heath status and distribution of plants in a specific vegetation region is a beneficial task in ecology, plant biology and plant growth analysis. Conventionally, researchers used quadrats for plant monitoring. The quadrat technique has a high demand in resources such as time and labor and the quality of data samples may be affected by human errors due to fatigue over the course of sampling or operator bias. Further, the conventional method is practical for only small scale use as it is. Identifying plants and detecting whether they suffer from biological and environmental stresses is an important step toward developing an automated system for monitoring plant establishment. However, the use of high-tech imaging systems makes it possible to monitor native plants in larger area and in real time. In this paper, the use of visible, hyperspectral and thermal imaging systems for monitoring environmental and biological stresses enforced on plants in small to large scales in arid and semi-arid environments will be discussed. The systems could be satellite-based, airborne or ground-based. The visible spectrum, 420-750nm, can be used for detecting seasonal changes in plants; while, the near infrared spectral range, 740-2500nm, and particularly the 950nm spectral band, can be used for detecting water stress and some biological disease. The imaging in far infrared, spectra with the wavelength of 8µm and more have been proven to be useful for detecting early to mid-drought impacts on vegetation.

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