Fire history, fire ecology and management in Argentine Patagonia: from ancient times to nowadays

DEFOSSÉ, G. E. ; GODOY, M. M.,; BIANCHI, L. O.; LEDERER N. S. ; KUNST, C.,

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

Nova Science Publishers

Lugar: New York; Año: 2015; p. 177 - 210

 Patagonia is a vast region in South America that covers the southern part of Argentina and Chile, from the 36° to the 56° S.  In Argentina, the Patagonian region comprises about 750 thousand km2 and goes East to West from the Atlantic Ocean to the Andean Cordillera and North to South from the Colorado River up to the Beagle Channel in Tierra del Fuego. Three main phytogeographic provinces occur there. The Monte Province, the Patagonian Steppe and the Andean Forests. Between the Patagonian Steppe and the Andean Forest, a narrow strip comprising about 2 millon ha is starting to be used for afforestation purposes, mainly with non native conifers such as ponderosa pine, Douglas fir and lodgepole pine.  The whole region is dominated by a Mediterranean climate, cold and humid during late fall and winter, followed by a dry and temperate period during spring and summer. This Mediterranean type of climate has favored the occurrence of wildfires from October to early April (mid-spring to late summer in the southern Hemisphere).  In  Andean Forests, there is evidence of fire 10,000 years B.P. in the early Holocene, where great magnitude fires took place in pure Nothofagus forests. Further in the mid-Holocene, between 6000 and 3000 years B.P., precipitations increased to the east and vegetation changed toward mixed Nothofagus ? Austrocedrus chilensis forests, shifting also the fire regime to more frequent and less severe fires.  Fire scars were also found in Fitzroya cupressoides and A. chilensis trees from 990 and 1437 AD, respectively.  From 1800´s to early 1900´s, human set fires increased in the forest piedmont, inducing vegetational changes to open shrublands and grasslands.  In 1930´s, a fire suppression policy began, and Austrocedrus forests started to recover toward the east. This trend, however, was not linear, and other disturbances such as logging for either timber or firewood, grazing, and increasing human population in the Forest-Steppe Wildland Urban Interface (WUI) have been shaping the landscape in a dynamic way.  In the other two provinces (Monte and Patagonian Steppe) there are also evidences that fire played a major role in vegetation dynamics, and that the introduction of grazing may have disrupted the pristine role of fire.  Studies about fire and fire effects in Patagonia done at present, have focused more on landscape or stand level than on individual species.  Nevertheless, it is evident that most species have developed strategies to survive fires of different frequency and severity.  These strategies varied from resprouting from their stem bases, the production of seeds resistant to fire, or the migration of seeds from adjacent unburned areas that would colonize open areas left by the fire.  In relation to conifer afforestations, the main objectives are focused at finding the ways (through the development of appropriate silvicultural techniques) of reducing wildfire hazard, allowing then for greatest growth and help mitigate global CO2 emissions.