Mountain roads affect the richness of native and exotic plants along the elevational gradient in the Arid Andes

Abstract

Background and aims: In order to contribute to the knowledge and conservation of the arid Andes flora, we explored how vehicular roads and elevation affect the composition and richness of plant communities. In addition, we aim to estimate the degree of plant invasion in the native community and identify the most common non-natives at three protected areas in Mendoza. M&M: We recorded the composition and abundance of native and non-natives along the elevation gradient (from 1700 to 3900 m a.s.l.) in three vehicular roads (Villavicencio, Cordón del Plata, and Manzano-Portillo). At each road, 20 “T-plots” were located according to the MIREN protocol. Results: We identified 357 species, 42 were non-native (12%). Non-native cover was higher at Cordón del Plata (23%) than in the other protected areas (Manzano 11%, Villavicencio 6%). Most non-natives were herbaceous, except Rosa rubiginosa. Of all species, 64% of natives and 45% of non-natives were exclusive to a protected area, therefore native and nonnative species composition was different among the protected areas. Non-native richness was higher near the road and decreased quadratically with elevation, but to explain native richness patterns it was necessary to consider the interaction between elevation and distance from the road. Native richness near the road was constant along the elevation gradient (~15 species) but showed a decreasing linear relationship away fromt he road. Conclusions: Roads can modify the distribution patterns of species along hte elevation in the Andes.