Abstract
Wildfires are a common phenomenon globally, nonetheless some ecosystems are more adapted than others. In this work, we show results of a study conducted in Torres del Paine National Park (Chile) that suffered a big forest fire in 2011, affecting 17,666 ha. The Park is located in the transitional forest-steppe zone whose annual rainfall varies between 300 and 1,500 mm. Plant communities goes from Patagonian steppe, pre-Andean scrub to Magellanic forest. Based on vegetation community and trying to cover all representative sectors affected by the fire, 5 areas of the park were sampled in 2019 following the transects where a vegetation recovery study has been monitored since the fire occurred. Soil parameters used to evaluate were: texture, soil water repellency (WR), organic matter (OM), and aggregation, including total content of macroaggregates (TCA) and their stability (AS). The results showed high values of OM, however three of the 5 areas showed statistically lower values of OM in burned samples. WR was present (from slight to severe) in the 75% of the samples, and without differences between burned and unburned. The correlations analyses indicated that WR is more related with the OM type than with quantity, since better correlations were obtained when only samples from the same area were included in the analyses. The results of aggregation indicated that soils have a poor structural development. The TCA varies from 16 to 50%, and the AS is not very high (average of 66%), being the highest in the area with lowest TCA and more affected by the fire and erosion processes. This suggests that the higher values of AS are a consequence of the destruction and loss of the less resistant fraction after the fire. The combination of the high sand content (low specific surface area) and high OM make them very susceptible to develop WR. Since these soils have a scarce development with a poor structure, the combination of the WR and the poor soil structure make them very vulnerable to erosion processes after the fire. Measures to protect the soils or accelerate the recovery are recommended in these areas when new human caused wildfires could occur.
Highlights
Wildfires are a common and natural phenomenon globally and have played a vital role in the history and evolution of ecosystems (Pausas and Keeley, 2009)
The following soil properties were analysed: pH, electrical conductivity (EC), soil texture, soil water repellency (WR), organic matter content (OM), and aggregation, including total content of macroaggregates (TCA; % of sample that are forming macroaggregates) and their stability (AS; % of macroaggregates that resist the energy of a rainfall simulation of known energy)
Fire can affect directly to the OM content depending on fire intensity and severity, previous studies have observed both increases or decreases depending on the fire behaviour (Mataix-Solera et al, 2002)
Summary
Wildfires are a common and natural phenomenon globally and have played a vital role in the history and evolution of ecosystems (Pausas and Keeley, 2009). The most likely source of these early fires was the indigenous population (Holz and Veblen, 2011). These authors documented an increase in the number of fires after the colonization and permanent settlement of the region by Euro Chileans. Fire does not form part of the ecosystem dynamics in southern Patagonia, meaning a lack of resilience to wildfire, and patches of the Patagonian steppe are exposed and more susceptible to be colonized by invasive species (Vidal, 2012; Kitzberger et al, 2016). The ecotonal zones between eastern semi-arid steppes and Nothofagus spp. forests in western Patagonia results from broad landscape and ecosystem changes, intensified in the last 140 years, with anthropogenic forest fires, logging, exotic pasture establishment, and mining as the leading causes (Zegers et al, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
