A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community,
information is given on physiognomy, floristic diversity, ecology and geographical distribution. The shrub vegetation on the
slopes of the upper Tambo river valley includes annual herbs, grasses, cacti and ferns. In total, 151 vascular species have
been documented from forty-six relevés made at altitudes between 3470 and 3700 m. After classification with TWINSPAN, one
class, one order, one alliance, three associations, two subassociations typicum and three subassociations, one variant, and
two communities are distinguished.
Hierarchically the class Echinopsio schoenii-Proustietea cuneifoliae comprises
the order Echinopsio schoenii-Proustetalia cuneifoliae, and the alliance Salvion oppositiflorae, occurring in the Prepuna
dwarf scrubs. Within the alliance the following 3 new associations (with subassociations) have been distinguished: Senecioni
arnaldii-Exhalimolobetum weddellii (thorny rosette-like dwarf shrubs), Mostacillastro gracile-Chuquiragetum spinosae (high
cover of shrubs) and Anredero diffusae-Diplostephietum meyenii (high cover of clustered columnar cacti and patches of thorny
Two communities have been distinguished: Opuntia rosea and Helogyne ferreyrae, and the community of Ophryosporus
heptanthus and Escallonia myrtilloides, which includes several introduced species growing on heavily grazed wet slopes. The
basal communities of Stipa ichu and Nassella asplundii have been also identified.
The most diverse families are Asteraceae,
Poaceae and Cactaceae, followed by Solanaceae and Fabaceae. The vegetation includes endemic, native and a few introduced species.
DCA was used to interpret the correlation between environmental variables and species composition. Species composition is
best explained by altitude, inclination and vegetation cover.