Nowadays drought remains a phenomenon that affects a wide variety of natural areas in many parts of the globe. Droughts are considered the abiotic factor with most harmful effects on forest areas, thus it is especially important to identify the locations with highest potential impact. Its temporal and spatial distribution, as well as the different types of drought defined, makes difficult its prediction and the impact degree that their appearance involve. Climatic drought, characterized by a temporal sequence with a higher frequency of atmospheric conditions that are unfavorable to the development of precipitation over a region, is the trigger of the process associated with the risk of biological drought. The methodology used to identify periods of climatic drought is mainly based on the analysis of climatic variables such as precipitation or temperature (in our case from the Digital Climatic Atlas of Catalonia). However, these analyses don?t take into account the physiological state of vegetation, a highly important variable that should be used to monitor the status of forest ecosystems vulnerable to droughts. Our aim is to evaluate the potential of satellite images regarding the identification of Mediterranean forest areas that could potentially have had a maximum affection during drought periods. We have integrated a series of images of TM/ETM+ sensors onboard Landsat 4-7 satellites, for the period 1984-2008 together with climatic data to detect drought in forest canopies. This integration may provide a readily applicable methodology for identifying the most vulnerable areas affected by droughts.

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