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

EFFECTS OF FIRE ON SURFACE ENERGY FLUXES IN A CENTRAL SPAIN
MEDITERRANEAN FOREST. GROUND MEASUREMENTS AND SATELLITE
MONITORING
J.M. Sánchez 1
1 Applied Physics Department, Un Castilla-La Mancha, Albacete, Spain
juanmanuel.sanchez@uclm.es
E. Rubio 1,2 , F. R. López-Serrano 3 , V. Caselles 4 & M.M. Bisquert 4
2 Regional Development Institute, Un. Castilla-La Mancha, Albacete, Spain
3 School of Agronomy Engineering, Un. Castilla-La Mancha, Albacete, Spain
4 Earth Physics and Thermodynamics Department, Un. Valencia, Burjassot, Spain
Abstract: Forest fires are one of the main agents involved in the change of
structure and function of ecosystems. In this work we used a set of 5
Landsat 5 Thematic Mapper (TM) images, of the years 2007-2008, covering
an area of mediterranean forest and shrubs, affected by a fire in the summer
of 2001. Two control areas (non-burned) were established, representative
of the pre-fire conditions in the burned areas. The simplified twosource
model STSEB was applied to elaborate instantaneous energy flux
maps, at the time of the satellite overpass. A Bowen station placed in the
study site permitted a previous validation of the results. Regarding the
energy fluxes the most remarkable is the increase of more than 150 W m -2
in sensible heat flux at instantaneous scale, and 40 W m -2 at daily scale,
and the decrease of more than 250 W m -2 at instantaneous scale, and 60 W
m -2 (2.1 mm/day) at daily scale, in actual evapotranspiration, observed in
the forested area. In the shrubs area, the fire effect is almost negligible
after 6 years, since the vegetation regenerates.
1 - Introduction
Forest fires are highly destructive for nature, affecting the landscape, the
natural cicle of the vegetation, and the structure and functioning of ecosystems.
Beyond that, they also provoke changes in the local and regional
meteorology, and particularly in the surface energy fluxes regimen. There is
an increasing concern among the scientific community about the effect of
forest fires on climate change at this point (Randerson et al., 2006).
Remote sensing techniques allow us to estimate surface energy fluxes over
large areas. In the present work we use the Simplified Two-Source Energy
Balance model (STSEB), developed by Sánchez et al., (2008a), applied to
high resolution imagery obtained from Landsat 5 Thematic-Mapper (TM).
The objective of this study is to quantify the effect of a forest fire in terms
of net radiation, and soil, sensible, and latent heat fluxes in two different
ecosystems, mature pine forests and shrublands.
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