Areas of endemism in the southern central Andes

AAGESEN, L., M. J. BENA, S. NOMDEDEU, A. PANIZZA, R. P. LÓPEZ & F. O. ZULOAGA

DARWINIANA

INSTITUTO DE BOTÁNICA DARWINION

Lugar: Buenos Aires; Año: 2012 vol. 50 p. 218 - 251

0011-6793

This paper analyzes the distribution of vascular plants species endemic to the southern central Andes(south-western Bolivia and north-western Argentina). All 540 species endemic to the study regions (approx.720600 km2) have been included in the analysis. The main part of the endemic species is found insemiarid habitats between 1500-3500 m asl pointing to the topographically complex plateau, slope, andvalley system of the southern central Andes as the main locations for its endemic flora. The distributionof the endemic species within arid sites is in contrast with that of vascular plant diversity in general,as the most diverse habitat of the region is the moist subtropical Tucumano-Bolivian Yungas forest ofthe eastern Andes slope. A total of 17 well defined and partly overlapping distribution patterns wereindentified. The broadest distribution pattern defines a general area of endemism for the southern centralAndes. This area extends through nearly the entire region and is defined by species that are widespreadwithin the region in desert to sub-humid environments of the high Andes, slopes, or valleys. Nearly allother areas of endemism are nested within this broad distribution pattern as successively north-southoverlapping areas along the slopes and valleys of the Andes and the Pampeanas Range. Despite thedistributional bias of endemism towards the arid sites almost half of the endemic species are restrictedto a few high endemic areas that lie in juxtaposition to the main rainfall zones. These areas contain thewidest habitat ranges in terms of altitude and rainfall within the region with the endemic species beingequally variable in altitude and moisture requirements. Previous defined phytogeographic units were notrecognized among the distribution patterns. However, the northern part of the Prepuna can be defined astwo partly overlapping distribution patterns.