ANALYSING VEGETATION RESPONSE TO TWO SUCCESSIVE FIRES USING SATELLITE SPOT-VGT NORMALIZED DIFFERENCE VEGETATION INDEX TIME SERIES

摘要

The ability of vegetation to recover after fire disturbance (resilience) is crucial in order to avoid or reduce land degradation. For this reason it represents one the most challenging questions in the framework of environmental monitoring. The response of vegetation of a test site in Sardinia Island (Italy) to two successive fires was investigated, using the 1998 to 2005 time series of Normalized Difference Vegetation Index (NDVI) from SPOT-VEGETATION sensor. The detrended fluctuation analysis (DFA) was performed in order to identify and quantify this response. The obtained results reveal that vegetation dynamics, persistently characterized, is featured by a quite high degree of resilience after the first fire, which lowers after the second fire. This result can be interpreted as a less efficient recovery mechanism, when the vegetation is repeatedly affected by fire stresses.