Effects of volcanic and hydrologic processes on forest vegetation: Chaitén Volcano, Chile

Abstract

The 2008-2009 eruption of Chaiten Volcano (Chile) involved a variety of volcanic and associated hydrologic processes that damaged nearby forests. These processes included coarse (gravel) and fine (silt to sand) tephra fall, a laterally directed blast, fluvial deposition of remobilized tephra, a variety of low-temperature mass-movement processes, and a pyroclastic flow. Each of these geophysical processes constitutes a type of ecosystem disturbance which involves a distinctive suite of disturbance mechanisms, namely burial by tephra and sediment, heating, abrasion, impact force, and canopy loading (accumulation of tephra in tree crowns). Each process affected specific areas, and created patches and disturbance gradients in the forest landscape. Coarse tephra abraded foliage from tree canopies over an area of approximately 50 km² north-northeast of the vent. Fine tephra accumulated in tree crowns and led to breakage of branches in old forest and bowing of flexible, young trees over an area of about 480 km². A directed blast down the north flank of the volcano damaged forest over an area of 4 km². Although some effects of the Chaiten eruption are very similar to those from the 1980 eruption of Mount St. Helens (USA), interactions between biota and geophysical processes at Chaiten produced some unique effects. Examination of vegetation response helps interpret geophysical processes, and disturbance mechanisms influence early stages of biotic response to an eruption.

Citation

Swanson, Frederick J.; Jones, Julia A.; Crisafulli, Charles M.; Lara, Antonio. 2013. Effects of volcanic and hydrologic processes on forest vegetation: Chaitén Volcano, Chile. Andean Geology. 40(2): 359-391.