Early observations of volcanic ash deposition and its impact on the vegetation steppes of NW Patagonia

Abstract

The Cordón Caulle volcanic complex, located in the Andes (Chile), have erupted in June 2011, and has has been emitting ash with different intensity since then, that the dominant winds have deposited in the Argentinean Patagonia. Here we quantifi ed the amount of deposited ash in the gaps between the vegetation of northwestern Patagonia steppe in order to estimate the early impact of ash on functional groups present in gaps; and we analyzed the relationship between post-eruption rainfalls and ash dynamics. We compared species frequency in pre-eruption gaps (November 2010) and post-eruption gaps (October 2011 and January 2012). Thickness average of ash deposited in gaps was 3.4 cm. Post-eruption rains were scarce and limited the ash incorporation into the soil, causing a greater impact on vegetation. Species presence in gaps was lower than usually registered in this microsite type. Recruitment of annual and matrix dominant species was not observed. The most common species was the exotic herb Rumex acetosella. Perennial grasses present in gaps have subterranean structures that allow them to reproduce after the deposition of volcanic ashes. Volcanic activity has been very important in this region and it is likely that species have evolved in the presence of this disturbance.