Abstract

KUNST, C et al. Dinámica de la humedad de los combustibles y su relación con la ecología y manejo de fuego, region chaqueña occidental (Argentina) II: follaje y residuos de árboles y arbustos. RIA. Rev. investig. agropecu. [online]. 2014, vol.40, n.2, pp.165-181. ISSN 1669-2314.

Fire is a common disturbance in the Chaco region of Argentina. The fuel moisture content (CH, %) is a factor defining inflammability and its changes throughout time. CH could be used to understand the fire regime and ecology, planning the use of prescribed fire and as an index of fire risk. In this research we assessed the dynamics of CH of the foliage (live fuels), litter and coarse woody debris (CWD) of different diameter (dead fuels) of 4 tree and 5 shrub native species. CH was monitored using the gravimetric method every 10-15 days from May 2008 to October 2009. Data were analyzed graphically and with analysis of variance using season, species and fuel type as classification factors. Litter showed a low mean CH (< 22%) with low variability but with a significant correlation with environmental variables (rainfall registered between sampling dates and soil moisture content at two depths 0-30 cm and 30-60 cm). Dead fuels presented a declining, almost lineal dynamics throughout time, suggesting a constant desiccation. Only in some cases showed significant correlation with environmental variables. Dead fuels of diameter 0.5-2.5 cm presented a high CH mean, and species were a significant factor. In live fuels, the average CH was variable and its dynamics followed a sinusoidal pattern with seasonal and intraseason amplitude. Shrubs presented usually a high CH mean and Schinus spp., a species with perennial leaves, showed the highest annual mean (CH ≈ 74%). In tree species, the mean CH was 45-50 %, with less variability than shrub species. Considering live fuels, the fire prone season would be from winter to early spring, while in woody residues would be the second winter after their cut. Litter showed an annual mean CH under the threshold of extinction (CH = 30%) and may be a key factor in fire propagation in the region.

Keywords : Fire regime; Fire risk; Chaco region.

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