Fire regime of a Elionorus muticus Spreng. savanna, western Chaco region, Argentina

Abstract

Our objective was to assess the current fire regime of a 600 ha savanna dominated by the grass species Elionorus muticus Spreng., located in Santiago del Estero Province, north-western Chaco region, Argentina. The degree of tolerance of some native woody species to fire, the fire mean fire frequency (FF), and Weibull median probability (WMPI) were evaluated. Sampling sites were located in the ecotone between the savanna and the surrounding forests. A database was developed from fire scars found in cross sections of native tree and shrub species, cut at different heights above ground; that covered the recent 70 years of fire history (1925–1996). Results indicate that the savanna has a mean FF of 0.179 fires year–1 and an FI = 3 years. The mean height of fire scars found in trees and shrubs which indicate medium to high fireline intensities with flame lengths larger than 1 m are frequent in the savanna. Native species have different degrees of tolerance: Aspidosperma quebracho blanco (tree) and Schinopsis quebracho colorado (tree) are more tolerant to fire than Acacia furcatispina (shrub) and A. aroma (shrub). Bark thickness of the tree species (1–1.5 cm in mature individuals) allows them to withstand the frequent, high intensity fires of the savanna.

Fire history and the global carbon budget: a 1°× 1° fire history reconstruction for the 20th century

“…The source is FAO (2001), and SEMARNAT for the 1980-1998 period. These data appeared to be low compared with local studies (Bran et al, 2001, Bravo et al, 2001 and national statistics from other agencies (Proyecto LEMU, http://orbita.starmedia.com/$lemuproyecto/ not8.htm) estimating up to three times the official statistics. As a general comparison with other biomes and neighboring countries, we retained the highest value as the most accurate.…”

Assessment of the rangelands of southwestern Santiago del Estero, Argentina, for grazing management and research

“…Although there is no information in the local literature indicating which frequency of S. quebracho colorado could be considered 'normal' in a Chaco forest, the frequency of this species in the study area could be considered low. The slightly greater mean frequency of A. quebracho blanco in comparison with the latter species in both the Southern Plain and Sierra Range Units could be attributed to its wind dispersed seed, high fire resistance and low preference by domestic livestock, features that make it very aggressive (Morello and Saravia Toledo, 1959;Bravo et al, 2001). The high mean frequency of A. quebracho blanco in the Rolling Plains could be attributed to the better adaptation of this species to coarser soil textures.…”

Fire–rainfall relationships in Argentine Chaco savannas

“…The fire frequency and fire interval documented in the studied savanna is representative of a fire regime of high frequency and medium to high intensity during the period of 1925e1996 (Bravo et al, 2001). The MFI of 3 years observed in the study area was Table 1 Mean Fire Interval (MFI), along two periods with different water availability and fire frequency in an Elionorus muticus savanna, Argentine Chaco region.…”

“…In the dry Chaco region of Argentina, fires usually start in grasslands and savannas, and may spread to surrounding forests and shrublands, depending on the amount of available fine fuel and wind speed (Bravo et al, 2001;Tálamo and Caziani, 2003). Bravo et al (2001) estimated a high frequency and a medium to high intensity fire regime over the last century for a typical savanna of the Chaco region.…”