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Médanos del Chaco National Park

Date of Submission: 06/04/2022
Criteria: (viii)(ix)(x)
Category: Natural
Submitted by:
Permanent Delegation of Paraguay to UNESCO
State, Province or Region:
Alto Paraguay
Coordinates: E 700955,38 N 7779136,58 - E 613101,39 N 7710417,38
Ref.: 6611

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The National Park Médanos del Chaco was created by Executive Power Decree No. 21,957 / 2003 with the mission of protecting the biodiversity of the area, a mixture of xerophytic ecosystems (forest, scrub, savannah, among others), endemic species of flora and fauna, the formation of paleo dunes as well as species of phytogenetic resources of global importance. Within its territory there is a relevant part of the Yrenda Aquifer System, the most important natural reserve of fresh underground water in the Chaco. Furthermore, within the limits a great portion of the Timané River is protected, a river that plays a vital role in the cyclical development of different ecosystems of great importance to the northern Paraguayan Chaco.

In 2016, through Law 5723/16 the surface of the Médanos del Chaco National Park was expanded to an area of 605,705 hectares and thus borders the Defensores del Chaco National Park, Kaa-Iya National Park of the Gran Chaco and its Integrated Management Area of Bolivia, establishing a Transboundary biological corridor of high conservation priority for the Dry Chaco eco-region.

From the geomorphological point of view, the area of the dunes or paleodunas, has a tubularly elevated relief, outstanding in the entire western Chaco, and is crossed by a complicated system of transverse and oblique faults, whose lips rise within the range of 1 to 20 meters. These particular characteristics lead to the development of a particular type of flora, some of the species are used for their edible fruits and others of great importance as phytogenetic resources, as they are wild relatives of cultivated plants.

The PNMCh constitutes a complex of vegetation that is changing according to the substrate of the sands (sandy soil) or more compacted soils of the sandy cambisol type. The transition begins in the vicinity of the Defensores del Chaco National Park, bordering the PNMCh. In this sector where the sands are not very well consolidated and the components of the vegetation formations are similar to those of the xerophytic forest typical of the dominant vegetation formations of the Chaco Seco Ecoregion. These characteristics make the area extremely fragile and in danger of being subjected to desertification processes.

Justification of Outstanding Universal Value

The Médanos del Chaco National Park with its more than 600,000 hectares helps to preserve the native fauna and a large part of the flora that develops on the wind dunes, the only formation in the country that deserves to be considered as a specific ecoregion. Its strategic location associated with its size can protect not only the type of the ecoregion, but also the surrounding transition areas such as the Defensores del Chaco National Park, the Cerro Cabrera-Timane Natural Reserve, and the continuity of the forest formations towards the east and southeast, on the dissected plain where the Teniente Agripino Enciso National Park is already located.

Probably the diversity of its flora and the size of its surface is a preponderant factor for the development of a good number of pollinating agents (especially insects, but also birds, beetles, and others, being invertebrates of little knowledge yet). All present vegetation in the PNMCh is a very strong buffer against wind erosion and the dragging of sandy sediments from the Grande and Parapití rivers, in Bolivia to the south and southeast of the Chaco.

The PNMCh houses the only known population of Paraguay of Lama guanicoe, "guanaco", this population is the most westerly of its natural distribution.

The PNMCh presents a pronounced climatic semi-aridity, characterized by dissected plains prone to erosion soils of aridic hydric regime, with a high risk of wind erosion when there is a predominance of eutrophic Regosols and a high risk of salinization and alkalization when Ordic Solonetz predominates. Its vegetation consists of fragile scrubland with partially uncovered soil, especially during the dry season.

These dunes are fixed in the summer by the herbaceous cover, in the dry season there is the moderate movement of sand towards the south by the persistent action of the north wind. It can therefore be said that this is a fragile habitat, as it has limited capacity to recover from anthropic disturbances.

The PNMCh is one of the core areas of the Chaco Biosphere Reserve together with the Defensores del Chaco National Park.

Criterion (viii): The geomorphological and edaphic particularity make the Médanos del Chaco National Park a site with great possibilities of containing endemic species and even new flora species for science.

The area of the dunes or paleodunes has a tubularly elevated relief, outstanding throughout the western Chaco, and is crossed by a complicated system of transverse and oblique faults, whose lips rise within the range of 1 to 20 meters.

This type of relief has been the cause of periods of intense activation of geomorphological activity. This was fulfilled, especially in extremely dry periods of periglacial type, or in transitional stages between dry and humid climates and vice versa. In the former, there were conditions of strong aridity, with aeolian deposition in the form of dunes and mantles, with deflationary processes leading to the formation of depressions, and the generation of evaporites in depressions and basins. The local manifestation of an active environment of this type, whose main documentary evidence is the origin and expansion of the dunes.

The post-glacial period created conditions that fixed the dunes and gave rise to a balance of local systems, capable of efficiently antagonizing the erosive action that dominated until then. These dunes, fixed by a particular vegetation, are unique at the local level and very rare at the regional level.

The dunes flow over the regional Yrendá aquifer, a very scarce freshwater reservoir in the region, generating well flow rates of 15 m³ / h and specific flows of 1.6 m³ / h on average. Freshwater sections are found from a certain depth, varying from 50 to 130

Criterion (ix): The physical conditions of the territory determine the development of very specific species of fauna and flora. Very preliminary studies of the region have yielded new species of flora and have identified important fauna endemism.

The aridity of the soil, the extreme climatic conditions represented by high and low precipitation, and almost constant winds; together with the particular edaphic characteristics (derive from specific geological features), generate the conditions for the development of particular species of flora, which support a very rich diversity of large mammals

The extension of the PNMCh, and its relationship with other conservation units make it the central point of a large biodiversity corridor that provides ideal habitat for the development of large mammal populations. Possibly the PNMCh is part of the territories of the southernmost populations of Panthera onca and the easternmost populations of Lama guanicoe.

Criterion (x): The PNMCh, together with the surrounding conservation units, forms the largest biological corridor of the South American Gran Chaco. The rich biodiversity includes more than 300 species of fauna, not including invertebrates, which for a xerophytic ecosystem is very broad. Rare charismatic species include Myrmecophaga tridactyla or Jurumi, Tamandua tetradactyla or Anteater, Priodontes maximus or Tatú carreta, Aotus azarae or Mirikina, Panthera onca or Jaguarete, Tapirus terrestris Mborevi or Tapir, Catagonus wagneri or Tagua, Lama guanicoe or Guanaco.

The importance of PNMCH for the conservation of the populations of the aforementioned species is fundamental, especially since they are associated with other conservation units and are part of the largest biological corridor in the Great American Chaco region.

Statements of authenticity and/or integrity

The purpose of this Protected Wilderness Area is to protect and conserve a representative sample of the Médanos Ecoregion, its natural and landscape communities, as well as being the core area of the Chaco Biosphere Reserve.

The consolidation process of the area has led it to be declared a National Park through Law 5723 with an area of 605,705 hectares and whose limits are defined in the same Law.

The National Park also has a management plan valid until 2027 and is currently the study area of a series of scientific research related to the biodiversity of the region.

The surface of the National Park and the coverage of the entire natural community of the dunes ensures that all the attributes necessary to convey the potential outstanding universal value of the property are included within its boundaries.

Comparison with other similar properties

Yguazu National Park, Argentina, was inscribed as a World Heritage Site in 1984 and, like the PNMCh, represents a globally unique ecosystem and is the habitat of important populations of endangered fauna.

The surface and the management conditions of both conservation units constitute an ideal refuge for sustaining biodiversity.

Unlike the Yguazu National Park, public use and access to the PNMCh are very restricted and very limited, due to its isolation and the landscape characteristics that make it outstanding within the Great American Chaco.

Noel Kempff Mercado National Park, in Bolivia, was included in the World Heritage List in 2000, under criteria (ix) and (x). This site is one of the largest conservation units in the Amazon, an ecosystem of global importance.

Like PNMCh, it has a mosaic of habitats characteristic of the ecosystem it protects, in this case the Amazonian evergreen forest with a gradient to savannas and cerrados. It also harbors viable populations of large mammals, several of which are globally threatened.

They differ in the type of ecosystem they protect, however both due to their size and biodiversity are of importance for the ecosystem they represent, one the Amazon and the other the Chaco.