Paisaje protegido Paso Centurión y Sierra de Ríos: A Detailed Map of Uruguay Borderland Landscapes

The Paso Centurión y Sierra de Ríos Protected Landscape was formally established as part of Uruguay's National System of Protected Areas (SNAP) on 8 July 2019 through Decree No. 198/2019, under the Paisaje Protegido, or Protected Landscape, designation. The creation of the area reflects a national effort to conserve representative examples of Uruguay's Sierras del Este system and the ecological transition zones that occur along the Brazilian border.

The protected landscape builds on a long-standing tradition of livestock ranching in the region, which has shaped the grasslands and helped maintain the area's overall naturalness. Designation under the protected landscape category, rather than a strictly strict-reserve category, recognizes this combination of natural and cultural values. Since its creation, ongoing biological surveys have continued to expand records of unique species and vegetation types within the park.

The protected landscape forms part of the Sierras del Este system in northeastern Uruguay, a region characterized by a mosaic of physical features rather than a single dominant landform. Rocky sierras and quebradas, or ravines, alternate with more rounded lomadas, raised plateaus, and undulating hill country, producing a varied relief across the protected area. These landforms create different exposures, slopes, and microclimates that support contrasting plant communities within short distances.

Because the protected area lies directly along the Uruguay-Brazil border, its landscape carries a distinctive southeastern-position character. The terrain reflects both Uruguayan sierras geology and the broader influences of the Mata Atlântica and Paraná subtropical forest regions just across the border. Natural grasslands, which are a defining feature of the area, occur in a patchwork alongside these woody habitats, often shaped by ongoing traditional livestock use.

Ecologically, Paso Centurión y Sierra de Ríos is defined by the meeting of major South American biomes. The protected area falls within the transition zone where Uruguayan sierras ecosystems meet the Mata Atlântica and the Paraná phytogeographic province. This transitional character gives the park unusual ecological richness and a vegetation profile that is more diverse than many other protected areas in the country.

Natural vegetation in the area includes subtropical forest elements with strong Atlantic Forest affinity, alongside native grasslands that are notable for their heterogeneity. The grasslands combine winter and summer species, annual and perennial plants, and species with varying growth habits, contributing to high ecological resilience, particularly in the face of climate variability. Woody plant communities occupy the sierras, quebradas, and plateaus, integrating with the open grassland systems to form a complex vegetation mosaic.

The protected area is also important as a refuge for species with distributions that are primarily centred in Brazilian subtropical forest biomes but reach their southern limits in this part of Uruguay. Botanical surveys have steadily expanded the list of first-time Uruguay records for various plant species within the park, reinforcing its importance as a transitional refuge.

The protected area has been documented as hosting at least 18 mammal species, and several of these records are considered notable or unique within Uruguay's system of protected areas. Among the most remarkable are records of the paca, the cuica de agua (a water opossum), the yapok, the jaguarundi (Puma yagouaroundi), and the aguara guazú or maned wolf (Chrysocyon brachyurus), the last of which represents a particularly significant occurrence in Uruguay.

Birdlife in the area also carries strong Mata Atlântica and Paraná forest affinity. The Chiripepé cabeza verde (a green-headed araçari-type bird) and the Yacutoro (Pyroderus scutatus) are recorded here as unique or especially significant occurrences for Uruguay, reflecting the area's role as a southern extension of Atlantic Forest avifauna. Combined with the area's position along an international border, these records mark Paso Centurión as an important step in understanding the wildlife connections between Uruguay and southern Brazil.

Paso Centurión y Sierra de Ríos is significant from a conservation perspective because it conserves a landscape that sits at the southern edge of two major South American biomes, the Mata Atlântica and the Paraná subtropical forest. Its inclusion in Uruguay's SNAP under Decree No. 198/2019 in 2019 reflects the country's recognition of the area's importance for representing transitional ecosystems and for protecting biota that are otherwise marginal or absent from Uruguay's protected-area system.

The protected landscape category chosen for the area acknowledges both ecological and cultural values. The natural heterogeneity of its grasslands confers notable environmental, economic, and social sustainability, as well as resilience to climate change, while the long coexistence of livestock-raising activities with natural vegetation has helped maintain overall naturalness. This combination of natural and cultural values gives the protected area a distinctive role in Uruguay's broader conservation strategy, emphasizing the maintenance of working landscapes alongside biodiversity protection.

The cultural dimension of the protected landscape is closely tied to traditional livestock ranching, which has historically shaped the natural grasslands and helped preserve their heterogeneity. Grazing systems within the park are regarded as part of the local cultural heritage, complementing the area's natural values and reinforcing its protected landscape, rather than strict-reserve, designation.

Paso Centurión's standout features include its position as a transitional refuge at the southern edge of the Mata Atlântica and Paraná subtropical forest, the heterogeneity of its natural grasslands and woody vegetation mosaic, and its record as a unique site within Uruguay for several mammal and bird species with Atlantic Forest affinities. The combination of sierras, quebradas, plateaus, and traditional ranching landscapes gives the area a strong and distinctive identity within Uruguay's national protected-area system.

As an evergreen reference, Paso Centurión is best experienced when its natural grasslands and subtropical vegetation are at their most expressive. Late spring through early autumn in the Southern Hemisphere generally brings warmer conditions and more active foliage growth, while cooler months can highlight the structural character of the grasslands and the visibility of wildlife signs in more open terrain. Seasonal conditions can also affect the experience of the rolling sierras and quebradas, which feel different under wetter versus drier conditions. Visitors interested in birdlife and the area's Atlantic Forest species may find periods when both native grasslands and forest vegetation are active, generally outside the deepest winter, most rewarding.