Fire regime and post-fire Normalized Difference Vegetation Index changes in the eastern Iberian peninsula (Mediterranean basin)

Abstract

Fire occurrence in Mediterranean landscapes has been studied widely. Despite this, a specific monitoring of vegetation recovery after recurrent fires by means of satellite images has been developed to a lesser extent. With the use of Satellite Remote Sensing (SRS) techniques and multi-temporal Landsat images of the area of Ayora (287 700 ha) in Valencia (Eastern Spain), between the years 1984 and 1999, we studied the post-fire regeneration of the Normalized Difference Vegetation Index (NDVI) in areas subjected to different fire recurrences. Emphasis is given to the effect of time since fire, precipitation, and bedrock types on post-fire NDVI changes. Results suggest that for the first 7 years after a single fire, NDVI depends mainly on the time since fire (post-fire regeneration), whereas environmental parameters (precipitation and bedrock type) are of little relevance. After this period, precipitation begins to have a direct influence on the NDVI. In patches burned twice, with fire intervals of 8 and 9 years, NDVI is also controlled by the time since fire. Furthermore, NDVI recovery is faster after the first fire than after the second fire, suggesting that fire recurrence has a negative impact on the resilience of these communities. Bedrock type did not show any effect on NDVI after fire. These findings contribute to the understanding of Mediterranean landscape dynamics and provide evidence for the usefulness of NDVI in post-fire regeneration assessment, and the possible negative effects of the increasing fire recurrences observed in the last decades.