Included here are the Andes, the Coastal Cordillera of Chile and the Córdoba Mountains of central Argentina. The Central Andes comprises two parallel mountain chains separated by a wide, high plateau known as the altiplano. Here the vegetation includes the so-called puna, salt flats (salares) and lagoons. The area once supported an extensive inland sea, but only salt flats remain. However, Lake Titicaca at an altitude of 3,812 m on the Peru and Bolivia border is the highest commercially viable lake in the world, and in terms of volume, is the largest lake in South America. The northern or tropical Andes has been described as the richest and most diverse biodiversity hotspot on Earth and has been described as a global epicentre of biodiversity.

Central Andean Wet Puna

Wet puna is mainly found in northern Peru, where it is influenced by moist air from both the Amazon Basin and the Pacific Ocean, and along the Eastern Cordillera, where most of the moist air comes from the Amazon Basin. On the altiplano it occurs at elevations ranging from 3,700 to 4,200 m.  On the Eastern Cordillera the vegetation is characterized by several species of Cortaderia. Between the tussocks there are often other grasses, sedges and low-growing forbs, together with ferns such as Jamesonia and lycopods such as Lycopodiella. Mosses and lichens are also common.

Central Andean Peat Bogs (Bofedales)

Peat is basically the remains of partially decayed plant material that accumulates in waterlogged situations. It is prevented from decaying fully by acidic and anaerobic conditions. However, peat bog are mainly associated with the more humid parts of the world, so it is rather strange that they occur here in one of the most arid parts of the world just east of the Atacama desert. It seems that groundwater is the prominent source of water and they generally lie in the bottoms of narrow, glacially modified alpine valleys or alpine basins at altitudes ranging from 3200-5000 m. Not surprisingly the vegetation of these remarkable peat bogs stands out in marked contrast to the surrounding vegetation. Much of it is composed of compact cushion plant formations (see above) mainly Oxychloe andina and Patosia clandestina while grasses such as Distichia filamentosa and D. muscoides dominate the ‘lawn’ and hummock formations. Sphagnum moss is also characteristic especially in northern peatlands. Wet peripheral areas typically include Deschampsia caespitosa, Deyeuxia velutina together with various species of Carex and Eleocharis.

Central Andean Aquatic Vegetation

In the Nevado Coropuna volcano area of southern Peru the aquatic vegetation often includes Azolla filiculoides and Ranunculus limoselloides, while the marshy areas typically include Distichia muscoides, Lilaeopsis macloviana, species of Carex and the endemic Werneria pygmaea (Asteraceae). Characteristic of the drier marsh margins are Calamagrostis ovata together with species of Astragalus and Lupinus. The aquatic vegetation of Lake Titicaca is characterized by Elodea potamogeton Juncus arcticus subsp andicola, Myriophyllum quitensis and Schoenoplectus californicus subsp. tatora. Growing in the shallow margins of high-Andean lakes in the centre-north of the eastern ranges of Bolivia are swards characterized by Lachemilla diplophylla and Lilaeopsis macloviana. These areas often become completely dry towards the end of the dry season. Other species here include Alopecurus hitchcockii, Cotula mexicana, Deyeuxia jamesonii, Distichia muscoides, Oritrophium limnophilum and Plantago tubulosa.

Northern Andean Aquatic Quillwort (Isoetes) Vegetation

These comprise communities of low nutrient páramos lakes dominated by endemic species of Isoetes (Isoetaceae) and aquatic bryophytes. These range in height from a few centimeters (e.g Isoetes socia) to about 60 cm in the giant Isoetes cleefii. Other species include Isoetes andicola, I. boyacensis, I. glacialis, I. karstenii and I. palmeri. All of these species belong to the section Laeves, which appears to have evolved in the neotropics and most are endemic to the tropical Andes. Isoetes karstenii forms a more or less closed community in some of the highest super páramos lakes (up to altitudes of 4425 m), which are often devoid of all other vascular plants. Typical bryophytes include Blindia magellanica, Isotachis serrulata and Fontinalis bogotensis. The tiny plants of Isoetes socia dominate shallow lakes of the high páramo. Here the few vascular plants include Elatine chilensis and the endemic Crassula bonariensis (Crassulaceae) and Ranunculus mandonianus (Ranunculaceae). Isoetes andicola, on the other hand, is completely different. It forms long boggy hummocks up to 80 cm thick along mineral shores in high altitude lakes. Few other species can be found here but the endemic Oritrophium limophilum (Asteraceae) and Plantago rigida (Plantaginaceae) may be present. Isoetes cleefii is also unusual in forming high (20-60 cm) dense communities in clear lakes of the high grass páramo with few other species, although bryophytes such as Calypogeia andicola may be present. Isoetes palmeri is charactersitic of peaty páramo lakes surrounded by boggy areas. A number of herbaceous amphiphytes, such as Eleocharis acicularis and Hydrocotyle ranunculoides are also charactersitic of these lakes. Isoetes glacialis, as the name suggests, occurs in high glacial lakes. These stands are often so dense that virtually all other species are excluded. Finally Isoetes boyacensis is a common dominant in pools on the calcareous slopes of the Páramo de Almorzadera.

Northern Andean Aquatic Vegetation with Tillaea paludosa

Vegetation dominated by the endemic Tillaea paludosa (Crassulaceae) is generally found in the shallow small páramo lakes and pools or along the shores of large, deep páramo lakes. Many of these are mesotrophic as opposed to the more nutrient poor (oligotrophic) condition of the ‘Isoetes’ lakes. Other aquatic herbs include Limosella australis and the endemic Juncus ecuadoriensis (Juncaceae), Lilaeopsis schaffneriana (Apiaceae) and Ranunculus limoselloides (Ranunculaceae). Similar aquatic communities have been found in the afro-alpine zone of several African mountains including Kilimanjaro. Here the dominant species include Crassula granvikii and Limosella africana.

Northern Andean Aquatic Vegetation with Equisetum bogotense

Pure stand of Equisetum bogotense up to about 25 cm high occur in various Andean aquatic conditions including lakes and rivers such as the Rio Lagunillas (Sierra Nevada del Cocuy). This species is widely distributed in the tropical Andes and also occur in the Galapagos Islands.

Northern Andean Mires and Swamps

North Andean mires and swamps may be dominated by bryophytes such as Marchantia plicata, cyperoids such as the endemic Carex bonplandi, C. pinchinchensis and Cyperus rivularis (Cyperaceae), graminoids such as the endemic Calamagrostis ligulata (Poaceae), and herbaceous forbs such as Gratiola peruviana and the endemic Galium trianae (Rubiaceae), Geranium confertum (Geraniaceae) or Lupinus alopecuroides (Fabaceae), or shrubby species such as the endemic Senecio reissianus (Asteraceae). Mires characterized by Marchantia occur in the upper páramo, the grass páramo and the upper forest belt. In the Colombian Cordillera other species include Epilobium denticulatum, E. meridense and the endemic Cardamine bonariensis (Brassicaceae), Cerastium imbricatum (Caryophyllaceae) and Stachys ellipica (Lamiaceae).  Galium trianae and Gratiola peruviana are characteristic of certain cyperaceous reed swamps which normally also include the bryophyte Philonotis andina and endemic vascular plants like Lachemilla mandaniana (Rosaceae). This association is found in the humid páramo in places like glacial valley floors and calcareous depressions. Cyperaceous swamps dominated by Carex pinchinchensis have a hummock-hollow relief. They are mainly in the sub páramo or grass páramo and have their optimal development in marshy glacial valleys. Associated species include the endemic Nertera granadensis (Rubiaceae), Valeriana plantaginea (Valerianaceae) and Senecio canescens (Asteraceae). Cyperus rivularis, on the other hand, is more characteristic of poorly drained peat in the wet sub páramo. Lupinus alopecuroides dominates eutrophic wet flushes with a rich herbaceous layer. Other species typically include Mimulus glabratus and the endemic grass Calamagrostis ligulata (Poaceae). The latter species also forms associations with Geranium confertum in páramo mires and marshy lakeshores. Shrubby association in which Senecio reissianus is the dominant shrub occur on eutrophic marshy or peaty ground usually on gently sloping glacial valley floors or in seepage zones. Other species include the endemic Carex pinchinchensis and Rumex tolimensis (Polygonaceae).

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