Influence of Soil Chemical Variables and Altitude on the Distribution of High-alpine Plants: the Case of the Andes of Central Chile

Temperature is one of the major abiotic factors influencing distribution and productivity of alpine plant species. Although some edaphic parameters (e.g. soil acidity) have also been suggested as determinants in the spatial distribution of alpine vegetation, there is little background on the importance of soil chemical properties in altitudinal gradients, particularly in the high Andes. The present study determined whether soil chemical properties affect spatial distribution and abundance of alpine plants in an altitudinal gradient in the Andes of central Chile, emphasizing metal content. A direct gradient analysis took place at Yerba Loca Natural Sanctuary (YLNS), based on a geobotanical sampling conducted in 73 sites distributed from 1970 to 3330 m a.s.l. According to a Canonical Correspondence Analysis, the main soil chemical factors that explain the pattern of compositional variation of high Andean vegetation are, besides altitude, total soil copper (Cu) content, percentage of soil organic matter, and available phosphorus and nitrogen. An analysis of shoot Cu content conducted in 19 plant species found in sites with highest soil Cu contents (>250 mg kg(-1)) showed high levels of Cu in their shoots (>100 mg kg(-1)). These results demonstrate species or ecotypes with optimal distribution in soils with high Cu contents, such as Armeria maritima, Trisetum lasiolepis, and Montiopsis potentilloides, which may have tolerance to this metal.