The puna grassland ecoregion, of the montane grasslands and shrublands biome, is found in the central Andes Mountains of South America. It is considered one of the eight Natural Regions in Peru, but extends south, across Chile, Bolivia, and western northwest Argentina. The term puna encompasses diverse ecosystems of the high Central Andes above 3200–3400 m.
Location
The puna is found above the treeline at 3200–3500 m elevation, and below the permanent snow line above 4500–5000 m elevation. It extends from central Peru in the north, across the Altiplano plateau of Peru, Chile and Bolivia, and south along the spine of the Andes into northwest Argentina.
Other sources claim that it goes on Suni (high plateaus and cliffs, some agriculture) and from 4000 m to the snow line (permafrost and alpine desert) of puna grassland (mountain tops and slopes, much colder).
Ecoregions
The puna is a diverse ecosystem that comprises varied ecoregions labeled wet/moist puna, dry puna and desert puna.
Wet/moist puna (Central Andean wet puna)
This ecoregion is a high elevation, wet, montane grassland in the southern high Andes, occurring from northern Peru to northern Bolivia. The wet puna shares its border on the west with the Sechura desert and the east with the wet Peruvian Yungas. The characteristically mountainous landscape contains high lakes, mountain valleys, snow-covered mountains, and plateaux. The high elevation of the wet puna (4200 to 5000 m) causes the area to have large temperature differences between night and day. The average annual temperature is low, ranging from 5 to 7 °C; with night frost periods from March to October. Temperatures shift from characteristic summer highs in the day and drop to winter lows at night. This extreme temperature shift has caused selective adaptation to occur and many endemic plants such as the Culcitium, Perezia, and Polylepis center their diversity in the wet puna. The ecoregion contains snow-capped peaks, glacial lakes, and several rivers that originate in the Cordilleras. The biggest lake in the ecoregion is Lake Titicaca, which is the highest navigable lake in the world, at an elevation of 3800 m (above sea level). The Suches and Tiwanacu rivers in Bolivia are the lakes tributaries. The areas in the north surrounding Lake Titicaca have eight wet months, and the areas in the south have one to two wet months. The average precipitation in this region ranges from 400 to 2000 mm.
Dry puna (Central Andean dry puna)
This ecoregion is a very dry, high elevation montane grassland of the southern high Andes. It extends into northern Chile and northwest Argentina and east into western Bolivia occurring above 3500 m between the tree and permanent snow lines. The vegetation of the dry puna consists of tropical alpine herbs with dwarf shrubs. Within the dry puna are salt flats, high plateaus, snow-covered peaks and volcanoes. Dry puna is distinguished from the other types of puna by its diminished annual rainfall. The dry puna has an 8-month long dry season and receives less than 400 mm of rainfall each year. The region lies at an elevation of 3500–5000 m above sea level. The dry puna is oligothermic as well. The average temperatures in this ecoregion range from 8 to 11 degrees Celsius and are lowest in the south. As a result of the elevation, varied temperatures and lack of rainfall, the Central Andean dry puna is a unique ecoregion with highly adapted flora and fauna. The southern region of the dry puna encompasses an even drier puna known as the desert puna. In the desert puna the average rainfall ranges from only 51–406 mm. The desert puna is dominated by the huge salt lakes and is known for the scattered halophytes around and in the depressions. These salt lakes are home to the endemic Andean flamingo.
The World Wildlife fund defines three distinct puna sub-ecoregions:
NT1003 Central Andean wet puna (Bolivia, Peru) – With about 1000 mm of precipitation each year, it tends to be covered by grasses mixed with herbs, lichens, mosses, and ferns. Wet areas have sedges and rushes. The Polylepis forests of 10,000 years ago were likely cleared by fire for agriculture and grazing. Many areas are farmed. It extends from north-central Peru, adjacent to the páramos, and reaches southeast to along the eastern altiplano of Bolivia. NT1002 Central Andean puna (Bolivia, Peru) – Covering most of southern Peru, the region is dominated by shrublands and thickets of tola shrubs. NT1001 Central Andean dry puna (Northwest Argentina, Bolivia, Chile) – Mostly in the southern part of the Central Andes along the western cordillera of Bolivia. There is little agriculture.