Abstract

FLORES GARNICA, José Germán. Sampling unit for determining the spatial variability of the surface area burnt by forest fires. Rev. mex. de cienc. forestales [online]. 2017, vol.8, n.43, pp.117-142. ISSN 2007-1132.

The strategies against forest fires are directed to priority areas, cartographically defined according to such criteria as fire hazard (inception, propagation, difficulty of control and impact). This is reflected, among other things, on the size of the burnt surface. Accordingly, the burnt surface can be considered as a support criterion for defining priority areas for protection against forest fires. However, the processes to determine their spatial variation must be standardized; otherwise, there may be a mismatch of their estimates between different zones. For this reason, among others, a common sampling unit must be defined in order to obtain comparable and compatible information. Thus, the objective of the present work was to determine a sample unit size that enables the capture of the spatial variability of the surface burnt by forest fires. Reference sites (RSs) were analyzed, considering: a) four sampling intensities (100, 300, 500 and 1 000 sites); and b) twelve RS sizes (1, 2, 4, 8, 10, 15, 30, 50, 70, 100, 150 and 200 Km2). The average burnt area in each RS was determined based on fire information for the state of Jalisco during the 2005-2015 period. The variability of the average burnt area diminished as the size of the RS increased, until an asymptotic behavior occurred. Considering that the data did not define a normal distribution, the Kruskal-Wallis test determined that there is a significant difference between RS sizes. An analysis between paired independent samples (Mann-Whitney test) defined that there is a difference between the sizes of neighboring RSs in the area where the asymptote begins. Finally, an RS of 100 Km2 was defined as the size of the common sampling unit to be used to generate a cartography of the spatial variability of the area burnt by forest fires.

Keywords : Priority areas; fuel loads; forest fire management; forest fire hazard; forest fire risk; reference places.

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