7th Workshop on Forest Fire Management - EARSeL, European ...

RELATIONSHIPS BETWEEN COMBUSTION PRODUCTS AND THEIR SPEC-
TRAL PROPERTIES IN FIRE-AFFECTED SHRUBLANDS
R. Montorio
University of Zaragoza, Zaragoza, Spain
montorio@unizar.es
F. Pérez-Cabello, A. García-Martín, V. Palacios & J. de la Riva
University of Zaragoza, Zaragoza, Spain
fcabello@unizar.es; algarcia@unizar.es; palacios@unizar.es; delariva@unizar.es
Abstract: Fire severity is considered an influencing factor in the post-fire
recovery dynamic of burnt areas. New research works point out the usefulness
of studying the individual combustion products which constituted the
burnt areas. This work aims for assessing the relationship between the main
combustion products and hyperspectral data and also for comparing the
sensitivity of the original reflectance values against the transformed data
(first derivative and absorption features analysis). Statistically significant
relationships are observed between the vegetation remains product and the
three spectral datasets. The black carbon and ash products are found to be
highly related with the first derivative dataset but not so good relationships
are observed with the other two spectral datasets. These results indicate
the higher sensitivity of the first derivative transformed data to combustion
products and the usefulness of this spectral information to the
assessment of fire severity.
1 - Introduction
Forest dynamic is highly influenced by fire, explaining the need for analyzing
the variables controlling postfire dynamic (Pérez and Moreno, 1998).
Within these variables, severity has been commonly considered as a critical
one to assess postfire effects due to its greater control in vegetation
response and erosion processes (Miller and Yool, 2002). Satellite data have
been proved suitable for detecting and mapping this variable because fire
disturbances in vegetation and soil produce detectable changes in their
spectral properties. In opposite to the traditional evaluation from spectral
intervals of severity indices new research works point out the usefulness of
estimating the presence of individual combustion products, especially those
associated with known fire severity levels (Smith et al., 2005). In this
framework, ground-level research works are a necessary first step to study
the actual spectral properties of the solid combustion products and the sen-
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