The main objective of this paper is to assess the spatial patterns of temperature distribution at the soil surface after a shrubland fire in a typical Mediterranean environment. The study was carried out by making experimental fires at a permanent field station (La Concordia, Valencia, Spain) in a typical Mediterranean forest slope. The set up consisted of nine plots (20 m long x 4 m wide) with similar morphology, slope gradient, rock outcrops, soil (Rendzic Leptosol) and vegetation cover (Rhamno lycioidis-Quercetum cocciferae association). Two different fire severities were evaluated, high (F1) and moderate (F2), created by the addition of limited amounts of biomass. To measure soil temperatures, two complementary methods were used: thermocouples and thermosensitive paints. Results show that peak temperatures on the soil surface measured by the two systems (higher than 600 C inmost cases) are quite similar and there are no statistically significant differences between them. The mean values of soil surface temperatures measured with thermosensitive paints were 240, 239 and 218 degreesC for F1 plots and 418, 448 and 435 C for F2 plots. Half of the 171 plots surface showed temperature values between 170 and 235 C, and in the F2 plots, these values ranged between 322 and 543 degreesC. Geostatistics were applied to analyze and describe the spatial variation of soil temperatures at the soil surface. Results showed that there are two dominant spatial patterns of temperature distribution (spherical and linear). The spherical model varied approximately between 4 and 10 m, and its pattern is related mainly to the natural biomass distribution and the time of flame persistence. In the second, the linear pattern, the temperature rise from the lower part to the upper part of the plot seems to be controlled by the meteorology at the time of burning, mainly by wind speed and wind direction. The spatial patterns of soil temperatures during the studied experimental fires affect soil properties in different ways according to the fire severity. This fact could contribute to change the spatial dynamics of soil nutrients that will play an important role in the recovery of the burned vegetation. (C) 2003 Elsevier Science B.V All rights reserved.
