Abstract

DE TORRES CURTH, Mónica I; GHERMANDI, Luciana  and  PFISTER, Gabriela. Fires in northwestern Patagonia: their relationship with meteorological conditions and anthropic pressure over a 20 years period. Ecol. austral [online]. 2008, vol.18, n.2, pp.153-167. ISSN 1667-782X.

Fires are the result of a complex interaction between meteorological and environmental conditions, and ignition sources. A careful knowledge of response to local environmental variables is necessary to deal with fires and to define adequate natural resource management policies. The goal of this study was to find relationships between precipitation, temperature, and number and size of fires, in northwestern Patagonia during the 1984-2004 period, in steppe and forest environments, which are separated by the 1200 mm isohiet of mean annual precipitation. We also analyzed the relationship between local, regional and national statistics, and the available resources for fire combat. In the forest, the burned area was associated with autumn-winter and spring-summer cumulative precipitation, and less with temperature. In the steppe, the burned area was associated with spring-summer cumulative precipitation and moderately with temperature. The number of fires showed a poor relationship to the meteorological variables and the burned area. An eighty-one percent of fires recorded in Patagonia happened in Rio Negro province, and of these, 50% where registered in the departament of Bariloche, showing a tendency to increase. An eighty-five percent of the burned area in Patagonia occurred in Rio Negro province, and only 0.3% of that area in Bariloche. The relationship between the number of fires and the burned area suggests that the combat tasks were effective except during seasons with extreme precipitation deficit and high temperatures. During dry winters or summers we can expect extensive burned areas in forest environments, and a summer with low precipitation will be enough for this to happen in the steppe. We have registered only two fire seasons with large burned areas, and both were related to a La Niña phenomena. The global change tendency will increase the frequency and amplitude of ENSO phenomena and, consequently, the risk of severe and extensive fires.

Keywords : Burned area; Number of fires; Precipitation; Temperature; Steppe; Forest.

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