Resumo

KUNST, C et al. Dinámica del contenido de humedad de pastos y su relación con la ecología del fuego en región chaqueña occidental (Argentina). RIA. Rev. investig. agropecu. [online]. 2015, vol.41, n.1, pp.83-93. ISSN 1669-2314.

Fire is a common event in the Chaco region of Argentina. The fuel moisture content (CH, %) is a factor defining flammability. Its changes throughout time could be used as an index of fire risk, to understand fire ecology, and for planning the use of prescribed fire. We assessed CH dynamics in three ecological sites (≈fuel models): samples with Elionorus muticus as dominant species (lowland, savanna); Trichloris pluriflora y Pappopphorum pappipherum (midland, parkand) and an exotic species Panicum máximum cv Gatton (upland, roller-chopped secondary forest). CH was monitored using the gravimetric method every month in the lowland during 1992; and every 10-15 days from May 2008 to October 2009 in the midland and upland sites. Data were analyzed graphically and with analysis of variance using season, chronological time and species as classification factors. The average CH of the species presented a marked seasonal trend, with a large amplitude, from 4-5 % in the winter to above 150 % in summer and fall, respectively. The CH of the native species was significantly lower than P. maximum, and also lower than the extinction threshold (CH = 30 %) suggesting that in the Chaco region, as well as in other ecosystems, grasses are the fuel where fire starts and propagate to other plant communities. Correlation between CH and the maximum air relative humidity observed between sampling dates was significant. The latter fact and the sinusoidal pattern of CH suggest that may be feasible the use of known mathematical functions and indirect methods to predict CH, helping in predict fire behavior throughout the seasons.

Palavras-chave : Fire ecology; Fire behavior; Vegetation.

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