Los Alerces National Park

Tourism is not currently excessive but has shown significant variation in recent years. Due to the COVID-19 pandemic, national parks across Argentina, including Los Alerces, experienced dramatic drops in visitation. No visits were recorded in April 2020 due to nationwide closures (Ministry of Tourism and Sports, 2020). In January 2023, 4,154 visitors were reported at the central entrance (SIB, 2023), increasing slightly to 4,431 in January 2024 (Yvera, 2024), but these remain far below pre-pandemic levels. Some high-use areas, such as the Millennial Alerce Forest Trail, have regulations and capacity studies in place, but no comprehensive site-wide study exists (Auditoría General de la Nación, 2021). Tourism is generally focused, inside the site on 10 trails (55 km).

Among the threats that could compromise the long-term integrity of the site, the ongoing invasion of red deer (Cervus elaphus), stands out as it has begun to expand within the protected area. This issue is currently addressed through the Exotic Ungulate Control Program. The presence of feral cattle is also recorded in specific sectors of the World Heritage site, although their current impact is not as significant as that of the deer. They are managed under the same control program. Meanwhile, authorised livestock grazing in the buffer zone (National Reserve) is subject to a specific management program aimed at minimizing the impacts of this activity.
With regards to feral livestock, concerns also relate to potential disease interactions with wild animal populations, as well as potential human health risks (IUCN, 2017). While some of these concerns are significant, overall the threat from invasive animal species to the Outstanding Universal Value of the property currently remains low.

Exotic species such as brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), brook trout (Salvelinus fontinalis), and Pacific salmon species, chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch), as well as Atlantic salmon (Salmo salar), have spread throughout Patagonian river basins.

However, some sub-basins have remained free of these species due to natural barriers such as waterfalls and cascades, which prevent their upstream migration. Los Alerces National Park contains several watercourses with these features, which has favoured the persistence of aquatic environments without exotic fish. In these areas, native fish species have been recorded, including the Patagonian perch (Percichthys trucha), large puyén (Galaxias platei), torrent catfish (Diplomystes viedmensis), Patagonian silverside (Odontesthes hatcheri), and the striped peladilla (Cheirodon australe). These native species are also present in water bodies where they coexist with salmonids, although under different ecological dynamics. The presence of autumn catfish (Trichomycterus areolatus) and small puyén (Galaxias maculatus) has not yet been confirmed within the park (IUCN Consultation, 2025).

A dam is located within the Los Alerces National Reserve which was built in the 1970s and therefore significantly predates the inscription. The infrastructure has significantly changed the visual integrity and ecology of a considerable part of the property (IUCN, 2017), with the reservoir areas extending into the Los Alerces National Park and even more significantly into the Los Alerces National Reserve which had been originally proposed as part of the nominated area, but was included in the buffer zone of the property by the World Heritage Committee Decision (World Heritage Committee, 2017). Considering that this infrastructure predates the inscription, the current level of this threat is assessed as low; however, IUCN in its evaluation of the nomination noted that “such large infrastructure development overall is a significant negative impact on integrity, and would clearly be inappropriate if proposed as a new activity in any natural World Heritage Site” (IUCN, 2017).

Livestock grazing is restricted to areas within the Los Alerces National Reserve which has been included as part of the property’s buffer zone. The total affected area is reported to be around 28,800 ha, which represents approximately 42.9% of the land area of the National Reserve with 1,000-1,200 large animals present (Management Plan, 2019). Grazing is not permitted within the World Heritage site, however, some challenges with compliance have been reported (IUCN, 2017).

Some effects of climate change have already been observed in the broader northern Patagonia region, including decrease in recorded rainfall, increased flammability in vegetation areas of medium productivity (shrublands) and retreat of glaciers (State Party of Argentina, 2016). A UNESCO and IUCN report found that the incidence of loss of glacial ice in the site is ranked number 2 globally for World Heritage sites (UNESCO and IUCN, 2022). However, overall current impacts on the Outstanding Universal Value of the property remain low, though monitoring is recommended based on the overall glacier melting potential in the larger region.

Los Alerces National Park has recently become the focus of scientific research centered on the effects of climate change, with particular attention on monitoring the Torrecillas Glacier. These studies, conducted in collaboration with the Geology Department of the National University of Patagonia San Juan Bosco, have deepened the understanding of the glacier’s geomorphological evolution and the risks associated with its retreat, such as glacial lake outburst flows (GLOFs). The studies have shown the rapid retreat of the covered glacier in the last 14 years and the development of a greater intensity of paraglacial phenomena. In recent years a Glacial Lake Outburst Flow type event was caused by the sudden entry of more than 12.000 m3 of debris, snow, and ice into the proglacial lake. Precipitation and temperatures above the average are being proposed as the triggering factor. Additionally, the detailed study of the Glaciar Torrecillas watershed allowed the recognition of threatening areas. Due to rising temperatures and decreasing precipitation in the last decades, and the short-term climate variability registered in the area, it is necessary to study and monitor unstable sites to detect gravitational phenomena (Reato et al., 2023a, b).

Based on this evidence, and following a GLOF event confirmed in September 2018, the park implemented management measures including the preventive closure of the trail to the glacier for visitor safety, and the design of a new trail to Lake El Antiguo, allowing continued public enjoyment of the area while minimizing exposure to hydrogeological hazards.

Since Los Alerces National Park was declared a World Heritage site, 24 fires have been recorded, all of which occurred exclusively within the National Reserve. According to site management that is, without affecting the declared World Heritage area (Velazquez, 2025). A major threat from fire is the entry of exotic invasive species (plants, fungi, algae, fish) as a result of forest fire suppression efforts.

In 2024, a wildfire thought to be the result of arson consumed thousands of hectares of the area. Some media outlets report the fire was within the World Heritage property. It is reported that the forest fire spread quickly, in the area of the lac Futalaufquen, in the province of Chubut, both within the National Park and beyond, and has consumed some 1000 hectares, out of the total 188 379 hectares of the site and the 207 313 hectares of the surrounding buffer zone (UNESCO, 2024). The UNESCO Heritage Emergency Fund (HEF) launched an initiative to strengthen active fire prevention. It is estimated that a total of 17,000 hectares of forest has been lost in the site since 2015 (UNESCO, 2024). Since the trend of fire is increasing, the significance of impact on the attributes of the site are significant and the capacity to respond is “medium” (State Party of Argentina, 2023), for the purposes of this assessment, the threat level is indicated as high.

In 2020, members of the Mapuche Tehuelche community of the Lof Pailako occupied land in the buffer zone, expressing territorial claims (Agencia Presentes, 2025). In early 2025, they left the site before a planned eviction could be enacted by the Ministry of National Security (Tiempo Agrentino, 2025).

Forest decline processes have been identified, the cause of which is still being studied. At the request of the protected area, various research groups are analysing whether these changes in vegetation (genus Nothofagus sp.) respond to specific events, the presence of exotic pathogens, or knock-on effects derived from climate change.

The decline of the alerce (Fitzroya cupressoides) forest in the ancient alerzal forest is also being investigated by the protected area in collaboration with the Andean-Patagonian Forest Research and Extension Center (CIEFAP). The main suspicion is that it is affected by Phytophtora austrocedri. The goal is to assess whether environmental stress or the presence of specific microorganisms may be affecting its stability. Phytophtora austrocedri also affects the Chilean cedar (Austrocedrus chilensis), mostly outside the Heritage site, and may potentially affect the Guaitecas cypress (Pilgerodendron uviferum).

The analysis of these processes will be key to understanding forest decline and defining conservation strategies adapted to current environmental challenges.

Systematic monitoring in areas within Los Alerces National Park—corresponding to the sub-basins of the Jara Stream, Menéndez River, Stange River, and Canelo River—has confirmed, to date, the absence of Didymosphenia geminata in these sub-basins. The continuity of this status is attributed to the sustained implementation of measures such as the use of nautical exclusion zones, the removal of sites from the recreational fishing regulations, institutional support for authorised service providers, and the operation of the disinfection station located at the southern entrance of the protected area (IUCN Consultation, 2025).

It is worth noting that all aquatic environments in the park with recreational boating activity show the presence of Didymo, whereas the protected areas have successfully prevented its upstream colonisation. In the cases of the Jara Stream and the Stange River, the species has only been detected at their discharge points, with no evidence of expansion into the upper reaches of the respective sub-basins. The persistence of these conditions reinforces the effectiveness of the preventive approach adopted and supports the continued need to maintain and refine management strategies, with emphasis on exclusion infrastructure and the periodic monitoring of sensitive sectors.

In water bodies located within Los Alerces National Park, fuel spills associated with nautical activity have been reported, both of low and high volume. In the cases documented, containment and/or remediation measures were implemented in order to mitigate their effects on aquatic ecosystems (IUCN Consultation, 2025). Microplastic and macroplastic pollution is a global phenomenon that knows no borders or protection categories, reaching even protected areas such as Los Alerces National Park. Recent studies have confirmed its presence in Lake Rivadavia, demonstrating that even ecosystems far removed from urban centers are not exempt from this threat. This issue has also been documented in other Patagonian environments, such as rivers and streams in Esquel, Trevelin, El Bolsón, and Corcovado, where microplastics have been found in sediments and aquatic organisms. Part of this dispersion can be explained by atmospheric mechanisms: microplastics released in urban areas or through recreational activities can be carried by the wind over long distances, becoming a form of airborne pollution that settles in water bodies located far from urban hubs (IUCN Consultation, 2025; Noticias Ambientales, 2025). The impacts on the site's key attributes is likely low, however the impact on other biodiversity values is likely greater.