CONICET scientists determine the impact of forest fires on bodies of water
·5 mins·
Notaspampeanas
Forest Fires
Andean-Patagonian Region
Water Resources
Rivers
Streams
Water Quality
Aquatic Ecosystems
Biodiversity
CIEMEP
Author
Notaspampeanas
Digging on curiosity and science.
Table of Contents
Table of Contents
Forest fires in the Andean-Patagonian region, in addition to transforming vegetation and fauna, also affect rivers and streams, where they can alter water quality and the functioning of aquatic ecosystems. Understanding how these bodies of water respond after a fire is key to assessing the impacts of these events and designing management strategies that contribute to the conservation of biodiversity and the ecosystem services associated with water resources.
Cholila-Golondrinas fire zone. Image credit: Assef et all..
A research team from CONICET’s Esquel Mountain and Patagonian Steppe Research Center (CIEMEP, CONICET-UNPSJB), in collaboration with researchers from the Chemistry Laboratory of the company INVAP, analyzed how a large forest fire that occurred in 2021 in Argentine Patagonia affected water quality and nutrient dynamics in streams of burned watersheds for 28 months after the event. This scientific contribution, made by Cecilia Brand,Yanina Assef, and collaborators, was recently published in the specialized journal Science of the Total Environment. It highlights the importance of understanding the effects of fire on headwater rivers and streams: “These ecosystems not only constitute an essential source of water for numerous communities, but also support multiple economic and productive activities in the Andean-Patagonian region,”Assef explained.
Sampling at fire sites. Image credit: Assef et all..
The large-scale forest fire originated near the towns of Las Golondrinas and El Hoyo in the province of Chubut and affected more than 13,000 hectares of Patagonian forest.According to the specialists, although this event caused significant environmental losses, including extensive forested areas and wildlife, it also represented a unique opportunity for the development of this work.
To assess the effects of the fire, the team compared four streams affected by the fire with four other reference streams that were not reached by the flames and have similar environmental characteristics.
“The study allowed us to identify and understand the so-called disturbance window—a critical period immediately following a fire characterized by high environmental vulnerability—which generally begins with the first rains after the fire. During this stage, we observed very marked increases in electrical conductivity and the amount of suspended solids, which manifested as increased water turbidity in the burned streams,”Assef explained. The researcher added that, during this initial period, phosphorus concentrations reached up to 17 times higher than those at the reference sites. “Subsequently, as phosphorus levels began to decrease, we observed a sustained and significant increase in nitrogen compounds, especially nitrates, a trend that continued until the end of the study,” she noted.
Meanwhile, Brand explained that the sustained increase in nitrates in the water is due to the fact that nitrogen transformation processes continue, but the capacity of burned vegetation to absorb nutrients is drastically reduced. This effect is proportional to the area of the watershed affected by the fire.
“In the first sampling, we also detected an increase in some heavy metals. What was striking was that this increase appeared in all the streams, not just those affected by the fire. The particles generated by the combustion were probably carried by the wind and deposited relatively uniformly throughout the area,”Assef said.
In this context, “CIEMEP’s geographical proximity to the affected area, coupled with the availability of vehicles, laboratories, and specialized equipment, was key to conducting regular monitoring and obtaining valuable information on how aquatic ecosystems respond after a fire,”Brand emphasized. Furthermore, she pointed out that, although forest fires represent one of the main disturbances affecting the region and cause severe social, economic, and environmental consequences, the impact of these events on water quality remains understudied, both in Patagonia and in Argentina in general.
“We started fieldwork in June 2021, just two months after the fire was extinguished, and since then we have maintained continuous monitoring that extends to this day, although the published article shows results from the first three years,”Assef explained.
As has been reported in other parts of the world, the specialists sustained that the effects of forest fires on aquatic ecosystems in the Patagonian region vary depending on the extent and severity of the fire, the size of the stream, the topography, and the type of vegetation cover. Furthermore, the most recent fires, such as those that occurred in Los Alerces National Park (Chubut) in 2024 and 2026, provide an opportunity to continue their studies and answer other questions that arose from the initial research.
Stream after a fire in the Andean-Patagonian region of Chubut. Image credit: Assef et al..
Assef and Brand emphasized that these results raise concerns about potential larger-scale ecosystem changes: “A sustained increase in nutrients over time can have consequences for ecosystem health, altering food webs and ultimately affecting drinking water quality.”They also warned that these changes can be exacerbated if combined with other activities that contribute nutrients to the water body or hinder the regeneration of riparian vegetation.
“We must keep in mind that as populations grow and inhabited areas expand into natural areas, wildfires are increasingly affecting watersheds used as sources of drinking water,”Brand pointed out. She concluded that “this makes regular water quality monitoring an essential tool for identifying potential fire impacts and ensuring the health and safety of communities.”
Cecilia Brand, Mauricio Dromaz, María Luciana Carignano, Cintia Ravasi, Yanina Assef, Impact of forest fires on water quality and nutrient dynamics in burned streams in Patagonia, Science of The Total Environment, Volume 1006, 2025, 180887, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2025.180887.
The article Determinan el impacto de los incendios forestales en los cuerpos de agua was published in CONICET’s website, and signed by CIEMEP Communications (CONICET-UNPSJB)
