The 2010–2015 Megadrought and its influence on the fire regime in central and south‐central Chile

Abstract

Citation: Gonz alez, M. E., S. G omez-Gonz alez, A. Lara, R. Garreaud, and I. D ıaz-Hormaz abal.Abstract. Forest fire activity has increased in recent years in central and south-central Chile. Drought conditions have been associated with the increase of large wildfires, area burned and longer fire seasons. This study examines the influence of drought on fire regimes and discusses landscape management opportunities to decrease fire hazard. Specifically, we investigate the effect of the 2010-2015 Megadrought (MD) compared to 1990-2009 period on fire activity (fire-season length, number of fires and burned area across months, fire sizes, regions and vegetation cover types, simultaneity, and duration of fires) in central and south-central Chile (32°-39°S), using contemporary fire statistics derived from the Chilean Forest Service. For large fire events (>200 ha) the average season length increased by 67 d (44%), comparing 2010-2015 to 1990-2009. Earlier and later ignition dates resulted in extended fire seasons in MD years. During the MD, the number, area burned, simultaneity, and duration of large fires increased significantly compared to the control period, including the unprecedented occurrence of large fires during winter. The burned area in large fires increased in all vegetation types, during the MD compared to the control period, especially in the exotic plantation cover type. The regions that were most affected by fire (i.e., total area burned) during the MD were Maule, B ıo-B ıo, and Araucan ıa (35-39°S) that concentrate >75% of forest plantations in Chile. Although both maximum temperatures and precipitation are drivers of fire activity, a simple attribution analysis indicates that the sustained rainfall deficit during 2010-2015 was the most critical factor in the enhanced fire activity. Future climate change predictions indicate more recurrent, intense, and temporally extended droughts for central and south-central Chile. Under this scenario, land-use planning and fire and forest management strategies must promote a more diverse and less flammable landscape mosaic limiting high load, homogenous, and continuous exotic plantations.

Anthropogenic drying in central-southern Chile evidenced by long-term observations and climate model simulations

“…The long-lasting and extended drought experienced in Chile in recent years serves as an analog for future climate. This phenomenon resulted in multiple often linked impacts affecting vegetation and watersheds (Garreaud et al, 2017), the biogeochemistry of coastal water ( León-Muñoz et al, 2018;Aguirre et al, 2018), and the intensity of forest fires (Urrutia-Jalabert et al, 2018;González et al, 2018), stressing mutually-dependent effects of the drought on Chile's socio-ecosystems. Responses from the public and private sectors generally considered this drought to be a transient event.…”

“…1900, with just one or two similar events in the last millennium (Garreaud et al, 2017). These recent years have been characterized by annual rainfall deficits ranging from 15 to 45%, a matching reduction in surface and underground water resources, detrimental impacts on vegetation and very active fire seasons (Garreaud et al, 2017;González et al, 2018). Unsurprisingly, this drought was perceived by most of the population, although its impacts in rural areas were more direct and more detrimental than in urban settings (Aldunce et al, 2017).…”

Modelling the current and future biodiversity distribution in the Chilean Mediterranean hotspot. The role of protected areas network in a warmer future

“…For the Box plots, red points indicate average values and p-value refers to Kruskal-Wallis analysis use change is concentrated in the Central Depression of MedCh, where native vegetation replacement by exotic tree plantations and agriculture (Armesto et al, 2010;Miranda et al, 2017) at accelerated rates in both space-time have been documented (Echeverria et al, 2006;Schulz, Cayuela, Echeverria, Salas, & Rey Benayas, 2010). The increase in fire events (Urrutia-Jalabert, González, González-Reyes, Lara, & Garreaud, 2018) as a consequence of anthropic influence and synergistically affected by a megadrought (González, Gómez-González, Lara, Garreaud, & Díaz-Hormazábal, 2018) has been another cause of the loss of native vegetation (Bowman et al, 2018). Forest fires pose large pressures over PAs and the matrix among them.…”

Initial response of understorey vegetation and tree regeneration to a mixed‐severity fire in old‐growth Araucaria–Nothofagus forests

“…Indeed, severe drought conditions, partially attributed to anthropogenic origin (Boisier, Rondanelli, Garreaud, & Muñoz, 2016), have been recorded in central and south-central Chile in the last decade (Garreaud et al, 2017). Since year 2010, annual precipitation has decreased 20-30%, promoting the increase in fire frequency and size, including in La Araucanía region (González & Lara, 2015;González, Gomez-Gonzalez, Lara, Garreaud, & Diaz-Hormazabal, 2018).…”

“…Araucaria-Nothofagus forests are typically shaped by a mixed-severity fire regime that includes surface and crown fires ignited by lightning and anthropogenic sources (González, 2005). Although Araucaria araucana is adapted to withstand moderate-severity fires or reestablish following high-severity fires (Burns, 1993), recent large, repeated high-severity fires may have hampered the potential resilience of these forests, especially under changing post-fire climatic conditions (Boisier et al, 2016;Garreaud et al, 2017;González et al, 2018). Furthermore, native plant species associated with Araucaria-Nothofagus forests also present strategies and adaptations to tolerate, survive and recover after high-severity fires (e.g., seedling establishment and resprouting), and the degree to which plants are adapted to fire strongly influences the structure and function of forests following a fire (Veblen, Mermoz, Martin, & Kitzberger, 1992;Veblen, Kitzberger, Raffaele, & Lorenz, 2003).…”