Drivers of crop impacts from tephra fallout

Abstract

Agriculture is an economic and social pillar for the least developed countries. When these regions host volcanoes that exhibit explosive behaviour, a serious risk for agricultural production arises as crops endure various impacts from tephra fall. In order to gain new insights into the factors that govern tephra impacts on crops, we collected farmers’ perceptions of crop damage and production loss due to exposure to tephra fallout in 15 villages affected by the 1999–2014 eruptions of Tungurahua volcano, Ecuador. Crop type and developmental stage - both influenced by altitude - strongly modulate the level of tephra-induced impact. Using these observations, we illustrate how crop vulnerability fluctuates spatially and temporarily in the surveyed area. The study also highlights that fine tephra (<63μm) is more harmful to crops than coarser particles. Farmers have responded to the tephra hazard by favouring crops more resistant to tephra, a practice that has reduced crop diversity.