Fire history and fire regime shifts in Patagonia temperate forests

Abstract

Fire has been a frequent disturbance in Patagonia. The presence of charcoal in sedimentary records covering the last 44,000 years suggests that natural fires played a significant role in shaping the landscape before the arrival of Native Americans ca. 14,500–12,500 years ago. Dendrochronological studies focused on the reconstruction of fire histories have been conducted in the Patagonian forests on both sides of the Andes Cordillera, beginning in the late 1990s. Here, we review the present knowledge of the history of fires in temperate forests in Patagonia, their main drivers, and discuss the evidence and impacts of burns and reburns on post-fire response, as well as possible mechanisms to shift into alternative stable states. Dendrochronology was extremely useful to develop multi-century fire histories in Araucaria araucana, Pilgerodendron uviferum, Fitzroya cupressoides and Austrocedrus chilensis and mixed Austrocedrus-Nothofagus dombeyi forests in Patagonia. In the case of Araucaria, Austrocedrus and Pilgerodendron forests, dendrochronological reconstructions show diverse and heterogeneous patterns of fire frequency related to changes in human activities and settlement processes over the last centuries. Fire history reconstructions document infrequent events in the Fitzroya wet rainforests, with ca. 800-year old in the Costal Range in South-Central Chile and ca. 1000-year old chronologies in the Argentinean Andes. Climate variability has a significant influence on fire occurrence in these Patagonian forests. Fire events have been strongly associated with low moisture availability linked to El Niño – Southern Oscillation (ENSO) and the Southern Annular Mode (SAM), the major climate drivers promoting fire. Future directions and challenges for fire history studies in Patagonian forests are proposed at the end of this chapter.