Fire History, Fire Ecology and Management in the Argentine Chaco.

KUNST, C.,; LEDESMA, R. ; BRAVO, S.; ALBANESI, A. ; ANRIQUEZ, A. ; SILBERMAN, J. ; DEFOSSÉ, G. E.; CASILLO, J.

Current International Perspectives on Wildland Fires, Mankind and the Environment.

Nova Science Publishers

Lugar: New York; Año: 2015; p. 211 - 234

In this chapter, we review some facts related to the ecology, history, and management of fire in the Chaco region of Argentina, South America. The Chaco is a fire prone ecosystem due to (a) the interplay of anticyclones and a low pressure center that results in cold and dry winters as well as rainy and hot summers, and (b) vegetation prone types made of hardwood forests, savannas and grasslands, which make available both fine and heavy fuels in the same space and time. As reported by historians, travelers, and ethnographers, native people used fire extensively. The extent in which these fires shaped the vegetation is unknown, but empirical evidences, such as historical pictures and accounts, indicate that fire kept the balance between the woody and grassy plant formations of the Chaco. They also suggested that return intervals of fires were long. The native tree and shrub species of the Chaco, belonging to the Aspidosperma, Schinopsis, Prosopis, Acacia, and Schinus genera are fire resistant. They have thick bark and/or resprout from the crown, if fire kills all aboveground structure. The fire return interval of the Chaco savannas is estimated being 3-4 years, similar to those of tropical and subtropical world herbaceous formations. Average fire frequency in the savanna helps maintaining its diversity and does not negatively affect soil properties. Mean flame lengths of headfires in savannas and grasslands are about 3-4 m and are considered of high intensity. In some cases, volatile fuels may act as fuel ladders, contributing to the occurrence of crown fires. The increase of the woody component of the vegetation and the loss of suitability of the current vegetation for livestock operations have brought the widespread use of mechanical clearing treatments and seeding of exotic grasses, such as Panicum and Cenchrus species. Such changes may affect the fire regime of the Chaco, generating complex fire management situations.