The Santa Marta páramo (NT1007) is an ecoregion containing páramo (high moorland) vegetation above the treeline in the Sierra Nevada de Santa Marta mountain range on the Caribbean coast of Colombia. The isolated position of the range has allowed unique species to evolve. Some are related to those found in Central America and the Caribbean coastal areas, and some to species from the Andes. The habitat is relatively stable, but has been drastically changed from the original by long-term human activity.
Geography
Location
The Santa Marta páramo has an area of . It covers the upper levels of the Sierra Nevada de Santa Marta in the north of Colombia. This is a roughly triangular massif with its north side parallel to the Caribbean sea, the southwest side facing the swamps of the Ciénaga Grande de Santa Marta and the southeast side facing the Serranía del Perijá mountains across the Cesar and Ranchería river valleys. The ecoregion is surrounded by the Santa Marta montane forests ecoregion, which in turn is surrounded by the Sinú Valley dry forests and Guajira–Barranquilla xeric scrub ecoregions.
Physical
The Santa Marta páramo is the most northern section of páramo (high moor) in South America. The isolated Sierra Nevada de Santa Marta has an elevation of . The páramo is found between the treeline around and the snowline around , with some variations due to differences in slope, rainfall and exposure to the wind and sun. The area is almost all granodiorite from the Jurassic period.
Climate
The Köppen climate classification is "Cwb": warm temperate, winter dry, warm summer. Where the Northern Andean páramo is generally humid throughout the year with moisture delivered in the form of rain, clouds and fog as air masses are lifted up over the mountains, the Santa Marta páramo is similar to the Costa Rican páramo and Cordillera de Merida páramo, where the northeast trade winds create a distinct dry season. Moist air currents rise every day and produce mist and rain. Most rain falls in May and September.
At a sample location at coordinates mean monthly temperatures ranged from in January to in June. Yearly average temperature was about , with average minimum of and maximum of . Average total rainfall was about . Mean monthly rainfall varied from in January to in May, falling back to in July and rising again to in October.
Ecology
The Santa Marta páramo ecoregion is in the neotropical realm, in the montane grasslands and shrublands biome. The ecoregion is part of the Northern Andean Paramo global ecoregion, which also includes the Cordillera Central páramo, Cordillera de Merida páramo and Northern Andean páramo terrestrial ecoregions. The plants and animals are adapted to the cold, dry conditions of the high peaks. There is a high level of local endemism, particularly on the more isolated peaks. The Sierra Nevada de Santa Marta has been designated a Biosphere Reserve due to the endemic plants and animals, particularly at the higher levels.
Origins
The Andes began to rise in the Miocene epoch, but in the north did not reach their present height until the Pliocene during a period of strong volcanic activity between four and five million years ago. This was the period when land rose above the tree line and the protopáramo vegetation was formed with new species of the Poaceae, Cyperaceae, Asteraceae, Ericaceae and other families. During the later parts of the Quaternary epoch there were alternating glacial and interglacial periods, with short, cold and dry periods alternating with warmer and more humid periods. The páramo belts moved lower and joined together in the cold periods, and moved higher into unconnected enclaves when the temperatures rose. The result is a mix of species of tropical and boreal origin with genera that are found in most páramos, but many endemic species in the individual páramos.
The Sierra Nevada de Santa Marta páramo is isolated and has a unique composition of flora and fauna. The isolation has given time for endemic species to evolve including the genera Castenedia and Raouliopsis. The species evolved from warm tropical species adapted to moist conditions and from Andean species that migrated along the eastern cordillera of Colombia. The flora is closer to the flora of the Cordillera de Merida páramo and the Cordillera de la Costa montane forests than to the Northern Andean páramo. It is descended from flora growing on land that was lifted to intermediate elevations in the early and middle Cenozoic, and that differentiated when the land was lifted to high elevations during the Pliocene and Pleistocene.