Sian Ka'an

Outstanding Universal Value

Brief Synthesis

Thousands of years ago the original Maya inhabitants appreciated the exceptional natural beauty of this stretch of coastline, naming it Sian Ka´an, or “Origin of the Sky". Located on the Eastern coast of the Yucatan Peninsula in the State of Quintana Roo, Sian Ka´an is one of Mexico's largest protected areas, established to manage 528,148 hectares of intricately linked marine, coastal and terrestrial ecosystems. Along its roughly 120 kilometres of coastline, the property covers over 400,000 hectares of land ranging from sea level to only ten m.a.s.l. The property boasts diverse tropical forests, palm savannah, one of the most pristine wetlands in the region, lagoons, extensive mangrove stands, as well as sandy beaches and dunes. The 120,000 hectares of marine area protect a valuable part of the Mesoamerican Barrier Reef and seagrass beds in the shallow bays. The lush green of the forests and the many shades of blue of the lagoons and the Caribbean Sea under a wide sky offer fascinating visual impressions.                 

The diversity of life in Sian Ka'an is exceptional. The tropical forests are home to charismatic mammals such as Jaguar, Puma, Ocelot and Central American Tapir. The property also provides habitat for a large number of resident and migratory bird species. There is a great diversity of marine life, including the West Indian Manatee, four species of nesting marine turtles and hundreds of fish species. About a third of the property is comprised of highly diverse and productive mangrove communities, of vital importance to fisheries in the broader region. Hundreds of forested islands, locally known as "Petenes", emerge from the flooded marshes, some reaching over a kilometre in diameter. A geological, biological and cultural particularity are the "Cenotes", deep natural sinkholes harbouring fascinating life forms, many of them endemic. This karst phenomenon results from collapsing limestone exposing groundwater.                            

Criterion (vii): The aesthetics and beauty of Sian Ka´an derive from the relatively undisturbed interface of sea and land along a well-conserved coastline. The mosaic of landscape elements is diverse in shapes, forms and colours allowing intriguing views and impressions. Noteworthy and rare natural phenomena include the "Cenotes", water-filled natural sinkholes hosting specialised communities of life and the "Petenes", tree islands emerging from the swamps. Both are connected by underground freshwater systems, jointly forming an invaluable and fragile treasure for future generations.

Criterion (x): The scale and conservation status of Sian Ka'an and its ecosystem diversity support a fascinating range of life forms. Over 850 vascular plants, including 120 woody species, have been confirmed in what is assumed to be a still incomplete inventory. In terms of fauna, noteworthy representatives among the more than 100 documented mammals include endangered species like Black-handed Spider Monkey, Yucatan Black Howler Monkey and the Central American Tapir. A small population of the vulnerable West Indian Manatee occurs in the coastal waters. Some 330 bird species have been recorded, 219 of them breeding in Sian Ka'an. Amphibians and reptiles are represented by more than 40 recorded species, among them the vulnerable American Crocodile and four of the six turtle species found along the Mexican coast, all reproducing within the property. The isolation of some of the "Cenotes" led to the evolution of several species which are locally endemic to single sinkholes. With some 80 recorded species of reef-building coral the portion of the Mesoamerican Reef within the property is one of the richest in Mexico. Jointly with the many other aquatic habitats it harbours more than 400 species of fish and a wealth of other marine life.

Integrity

The extensive property covers a large wetland complex, tropical forests, a diverse coastline, mangroves and a fascinating marine area with noteworthy corals and seagrass beds, all in a good overall state of conservation. Large tracts of the dense forests, mangroves and marshland are difficult to access and the poor soils and the vulnerability to storms and flooding have contributed to maintaining the mosaic of ecosystems. Many of the boundaries coincide with landscape features, such as the natural edge of the marshes in the South-East or the limits of the Espiritu Santo Bay catchment in the South. In the ocean, a depth of 50 metres has been defined as the Eastern boundary of Sian Ka'an. The property is of great importance to support the continuity of the intricate connections between terrestrial, marine and freshwater ecosystems and their rich flora and fauna. Sian Ka'an embraces a self-protecting system that is characteristic of the coast of the Yucatan Peninsula: the Mesoamerican Reef shelters the landward mangroves and seagrass beds, while the mangroves trap sediments, filter pollution and serve as nurseries for many vertebrates and invertebrates in the reef. In other words, these major landscape and seascape features are of vital importance to each other. It is therefore indispensable to consider them jointly in management and conservation, as is the case in Sian Ka'an. The contiguity with the almost 90,000 hectares protected as Uaymil Flora and Fauna Protection Area to the South and other important marine and terrestrial protected areas nearby likewise contribute to the integrity of Sian Ka'an.

Requirements for protection and management

After the historic abandonment of the area, inaccessibility, frequent flooding and poor soils allowed for centuries of natural regeneration, until governmental schemes encouraged timber extraction and land clearing for cattle pastures in the 20th Century. The undesired effects of uncontrolled development led to the creation of a nature reserve in 1982, consolidated in 1986 when the area was categorized a national biosphere reserve by Presidential Decree and also internationally recognised. More recently, Sian Ka'an was also recognised as part of a vast Wetland of International Importance under the Ramsar Convention. The large property is federally owned with the exception of a small patch of private land of around one percent of the total area on the Northern coast. Today, Mexico's National Protected Areas Agency (CONANP) under the Ministry of the Environment (SEMARNAT) is in charge of management, cooperating with partners at all levels of government. A management programme is to guide all activities and zoning. The involvement of local communities, governmental representatives, Academia and non-governmental organisations in management is promoted through an Advisory Council.

Sian Ka'an is susceptible to frequent and heavy tropical storms. The barrier reef provides natural protection for the coast, a telling example of conservation contributing to disaster preparedness. As for human impacts, the inaccessibility protects large tracts of the property. Besides the coastal fishing villages of Punta Allen and Punta Herrero, there are few permanent residents in the property. Hunting, fishing and collection of forest products, however, are widespread. Sport fishing and commercial fishing to supply nearby tourism centres has resulted in marked declines of some species, notably the Spiny Lobster. Management responses are needed. Agriculture north of the property bears pollution risks pollution and fires set to clear land have repeatedly spread into the property. Alien invasive species are reported, mostly along the dirt tracks on land but also in the ocean. The main economic sector directly and indirectly impacting on the property, however, is tourism. Fishing lodges and clubs, small hotels, cabins and trailer parks are the visible manifestations within the property. Tourism has reached proportions of mass tourism along parts of the Yucatan Coast and the property is in the vicinity of Tulum and Cancun, two of Yucatan’s major tourist attractions. Associated coastal urbanisation with, for example, well-documented garbage and sewage problems, require monitoring and management responses. Attempts to encourage low impact forms of tourism in the property to promote public awareness and visitor education but also as a source of conservation funding deserves consolidation.

Long Description

Sian Ka'an is situated on the eastern side of the Yucatán Peninsula in the state of Quintana Roo. Where possible, boundaries were defined to coincide with natural features: the site is bounded by the Caribbean Sea and the barrier reef to a depth of 50 m in the east; by the junction between the marshes and semi-evergreen forests in the south-east; and by the junction of Chetumal and Espiritu Santo bays catchment basin in the south. The northern and north-eastern boundaries are defined by the limits of farming cooperatives. The northern sites can be reached by a dirt track from Tulum, whereas Punta Pajaros is only accessible by boat or aircraft.

Sian Ka'an lies on a partially emerged coastal limestone plain which forms part of the extensive barrier reef system along the eastern coast of Central America. Much of the reserve lies in a zone of recent Pleistocene origin which still appears to be in a transitional stage. A large series of sinkholes (cenotes) exist in the area and are characteristic features of the Yucatán and Florida peninsulas. The hydrological cycle is complex and the water table is permanently close to the surface. There is little surface running water within the reserve as it usually filters fairly rapidly through the shallow rendzina and saskab (granular whitish and brittle limestone) soils, and the limestone rock to subterranean channels. Owing to their hardness the waters in the reserve are generally very clear. A geological fault crosses the reserve from south-west to north-east, influencing its topography and hydrology. In general, soils are unsuitable for agriculture.

Medium altitude semi-evergreen forest represents the climax vegetation in non-flooded areas, although it is scarce in accessible parts due to disturbance. Some 120 trees and shrubs have been recorded, including larger trees. Some 100 tree and shrub species have been identified in medium and low semi-deciduous forest. The abundance of palm is a characteristic feature of this forest type. Flood forest is subdivided into low forest with closed and open canopy tree communities, the latter being found in lower, wetter areas. It can form monospecific 'islands' on patches of dark soil. Grass communities cover large areas to the south and north and occur among mangroves and inland forests (although not in areas of high salinity). This vegetation type occurs as a mosaic with three intermingled associations. Low islands known as hammocks or petenes emerge from the flooded marshes. Larger petenes may have a central waterbody. There are extensive areas covered by scattered dwarf mangroves to the east of the freshwater marshes.

Coastal dunes stretch along 64 km of the coast, from the northern limit of the reserve to Punta Allen and from Punta Hualastoc to Punta Tupac. As Sian Ka'an lies so close to the Caribbean islands, there is a strong affinity between their flora. The introduction and cultivation of coconut has replaced about 60% of the natural vegetation on the coastal dunes. Selective felling has affected mahogany, red cedar and white cedar. There are an estimated 1,200 plant species.

As regards the Sian Ka'an fauna, a total of 103 species of mammal has been recorded including five species of cat - jaguar, puma, ocelot, margay and jaguarondi. Other mammals include Central American tapir, Caribbean manatee, spider monkey, howler monkey, kinkajou, white-tailed deer, red brocket, white-lipped peccary, paca, tayra and collared anteater. Some 339 bird species have also been recorded, with about two-thirds breeding inside the reserve. Due to the great diversity of aquatic habitats, marine and wading birds are well represented. There are 16 raptor species, as well as frigate bird, cormorant, roseate spoonbill, greater flamingo and jabirus; and 42 species of amphibian and reptile have been recorded. These include four of the six turtle species found along the Mexican coast; green, hawksbill, loggerhead and leatherback. Morelet's crocodile and American crocodile also occur. Fish are abundant, and over 52 species have been recorded. A total of 550 terrestrial and 843 aquatic invertebrate species have been observed.

There are 23 Mayan sites in the reserve, while the Chunyaxché ruins, Vigia Del Lago and Xamach, are just to the north. Recently, a 24 km Mayan artificial canal was discovered. The reserve is located in the least-developed part of Quintana Roo, and the population is predominantly of Mayan origin, in whose language Sian Ka'an means 'Origin of the Sky'.