JJ5
in the superparamo of the Cordillera Central and Oriental and in the Sierra Nevada de S. Marta. VaZeriana pZantaginea is only known from atmospherical humid Colombian and E~uadorian paramos between 3400 and 4400 m. In the northern paramos of the Colombian Cordillera Oriental and in the Sierra Nevada de S. Marta, VaZeriana pZantaginea is rather scarce. The Caricetum pichinchensis is probably present in paramos of the Colombian Cordillera Central and the Ecuadorian Cordillera Oriental. Notes: Small patches dominated by a bluish Carex sp. (probably C. pichinchensis) have been studied on the volcanoes Purace (3300 m) and S. Isabel (4170 m) and in the Sierra Nevada del Cocuy (3950 m). These communities do not contain VaZeriana pZantaginea and may represent another syntaxon. According to Dr. T. Koyama (NY) another large Carex species, C. fecunda, is locally found together with Carex pichinchensis.
50.
Community of Carex pichinchensis and PoZytrichum commune table II
Physiognomy: layer of 10-20 em.
This type of sedge swamps is
characterized by a musci
Composition & syntaxonomy: PoZytrichum commune is the most characteristic species, which furthermore only has been recorded in paramo Sphagnum bogs. Sphagnum mageZZanicum is common in rel. 80 and apparently develops into Sphagnum bog. ArcytophyZZum muticum, Hypericum prostratum, Geranium sibbaZdioides, CaZamagrostis bogotensis and PaspaZum bonpZandianum mark the transition towards the surrounding dry grass paramo. PoZytrichum commune, ArcytophyZZum muticum, Geranium sibbaZdioides, Leptoscyphus cZeefii and Hypericum prostratum are not present in other reedswamp communities. Synecology: This community of sedges and mosses is found along paramo streams on thick humid (rel. 144) and wet ground (rel 80) and is flooded in the wet season. The dark reddish-brown to gray silty to clayey soil layers in rel. 144 are str.eam deposits, the gyttja in rel. 80 is a lake sediment, now deeply incised by the adjacent stream. Rootzone soils are acid: pH 4.5-4.7. In rel. 144, at a depth of 70 em, the soil consists of a 1.5 em thick compact layer of plant remains, charcoal and fragments of gra7el. Oxydation colours can bP. noticed above this layer. PoZytrichum commune is common, and the layer is 1.5-20 em thick. Sphagnvffi mageZZanicum cushions (up to 10 em) grow on litter. Rel. 80 has a dense cover of the hydrophytic CaZamagrostis cf. pZanifoZia. Distribution: This sedge community, studied in the Paramo de Chisaca (3600-3700 m), was also observed at 3.520 m on the Nevado d路e Sumapaz and can be expected elsewhere in the Paramo de Sumapaz. Other cyperaceous communities
51.
Community of Carex acutata characteristic rel.: 26.5; table II; Fig. SO, 51
Physiognomy, composition & syntaxonomy: These two-layered paramo reed swamps contain Carex acutata dominant in the field layer. The bryophyte layer is dominated by Symphyogyna sinuata (3-4 em high) in well-developed stands. This type of sedge vegetation is poor in species; the average number is 10