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.

Central Andean Tola Heath Puna

Found at elevation ranging from 3,500-5,000 m, the rainfall in these zones is very seasonal with dry seasons lasting up to eight months. This unique vegetation extends from the Peruvian Western Cordillera crossing the central altiplano in northern Bolivia and then gets restricted to the eastern edge of the altiplano in southern Bolivia. The sparse vegetation is typically dominated by shrubs up to 1 m high often characterized by tola (Parastrephia lepidophylla), but there are also small stands of Polylepis, the only arborescent genus that occurs naturally at these high elevations. Vast areas are also covered by bunch grasses, typically dominated by Festuca orthophylla especially in the slightly wetter areas, and cushion plants may also be present. Other typical plant genera include Aciachne, Adesmia, Margyricarpus and Tetraglochin, and there are various species of Andean camelids. All of the flora and fauna are highly adapted to the extreme conditions.

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.

Northern Andean Bunchgrass Páramo

Páramo characterized by bunches or tussocks of the endemic grass Calamagrostis effusus (Poaceae) ranges in altitude from about 2900-4500 m on moderately acid soil and where foggy conditions often prevail. It generally includes a scattering of stem rosettes of the endemic genera Espeletia and Espeletiopsis (Asteraceae). In fact, several species such as Espeletia barclayana, E. brachyaxiantha, E. jaramilloi and Espeletiopsis corybosa, E. guacharaca, E. muiska and E. colombiana are more or less restricted to bunchgrass páramo. Other common species may include the endemic Castratella piloselloides, C. rosea (Melastomataceae), Cortaderia sericantha (Poaceae), Gnaphalium antennarioides, Hieracium avilae (Asteraceae) and Lobelia tenera (Lobeliaceae), many of which are sessile rosettes or tufted species. At the highest parts of this zone (3900-4500 m) Calamagrostis effusus can attain ground cover percentages of over 50%. Here the common stem rosette species are Espeletia lopezii, E. cleefii, E. azucarina and Espeletiopsis colombiana, E. guacharaco and E. santanderensis, and they are typically accompanied by the endemic dwarf shrubs like Diplostephium colombianum (Asteraceae) and Loricaria complanata (Asteraceae).

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 Cushion Bogs

Andean bogs dominated by low cushion chamaephytes and geophytes are mainly found at altitudes between 3400-4500 m, but in some locations, such as the Bolivian Andes, these have been recorded up to 5400 m. The key species often include the endemic Castilleja fissifolia (Orobanchaceae), Distichia muscoides (Juncaceae), Plantago rigida (Plantaginaceae) and Werneria pygmaea (Asteraceae). These bogs range across the high tropical Andes from Argentina and Chile to Colombia and Venezuela and correspond roughly to the distribution of the main character species Werneria pygmaea together with some of the small endemic Andean juncaceus genera Distichia, Oxychloe (e.g. Oxychloe andina) and Patosia (e.g. Patosia clandestina). More or less restricted to the northern Andes is the sub-alliance dominated by the endemic Oritrophium limnophilum (Asteraceae) and Werneria pygmaea. This occurs in small, deep valleys and on glacial valley floors, and commonly includes a number of endemic species with very limited distributions including Erigeron paramensis (Asteraceae), Floscaldasia hypsophila (Asteraceae), Vesicarex collumanthus (Cyperaceae) and Werneria crassa (Asteraceae). In places the latter may become dominant in its own right and may be associated with the endemic Lysiopomia sphagnophila (Lobeliaceae), but various other association occur. Another example includes cushion bogs characterized by Altensteinia paludosa and the endemic Castilleja fissifolia (Orobanchaceae) and Gentiana sedifolia (Gentianaceae) together with various bryophytes. This alliance is characteristic of partially filled glacial lakes, and in some of these the cushions actually float. Others are either soligenous or ombrogenous with the latter occurring in the highest parts of bogs and completely dependent on atmospheric water sources. Associated species often include the endemic Cortaderia sericantha (Poaceae).

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