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Título
Burn severity influence on post-fire vegetation cover resilience from Landsat MESMA fraction images time series in Mediterranean forest ecosystems
Autor
Facultad/Centro
Área de conocimiento
Datos de la obra
Remote Sensing of Environment, 2016
Editor
Elsevier
Fecha
2016-06-23
Abstract
Mediterranean ecosystems are adapted to recurrent forest fires by having regeneration mechanisms that overcome the
immediate effects of fire. However, the increasing frequency of fires in most European Mediterranean countries is challenging
the natural regrowth capability of these ecosystems. In this context, monitoring post-fire vegetation recovery is a
priority for forest management and soil erosion control. In this work, a 13-year series (1999–2011) of Landsat 5 Thematic
Mapper (TM)/Landsat 7 Enhanced Thematic Mapper (ETM +) data was used to model post-fire vegetation recovery as a
function of burn severity and to quantify post-fire resilience as a measure of vegetation cover regrowth. We evaluated a
large forest fire located in Spain that burned approximately 30 km2 of Pinus pinaster Ait. in August 1998. 88 field plots of
four burn severity levels (unburned, low, moderate and high) were measured in the field a year after the fire. As a variable
representative of vegetation, we chose the shade normalized green vegetation fraction image (SGV) obtained by applying
Multiple Endmember Spectral Mixture Analysis (MESMA) to the original Landsat TM/ETM + images. The SGV values
were extracted for the 88 field plots and, after performing a one-way analysis of variance (ANOVA), a Fisher's Least
Significant Difference (LSD) test allowed us to estimate resilience of vegetation cover as the number of post-fire years
exhibiting a statistically significant difference between burned and unburned areas. Next, SGV values were referenced
to unburned control plots values and the vegetation recovery index (VRI) was defined. The evolution in time curve of
VRI for low, moderate and highly fire affected vegetation was fit using trend models (specifically, an exponential trend
for VRI in high and moderate burn severity levels; a linear trend for low burn severity level, Root Mean Square Error,
RMSE = 0.18, 0.13, and 0.09, respectively). We observed that vegetation cover affected by low severity fire recovered
to its original state after 7 years, and vegetation cover affected by moderate severity recovered after 13 years. Vegetation
affected by high severity fire was estimated to recover after 20 years. We conclude that VRI time series based on multitemporal
MESMA fractions from Landsat data can be considered a valuable indicator of the post-fire vegetation cover
recovery. Its temporal evolution represented post-fire vegetation cover regrowth adequately and facilitated the estimate
of vegetation cover resilience in Mediterranean forests
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