Volcanic eruptions have significant impacts on any surrounding forests. During major eruptions trees may be scorched or flattened by lateral blasts & pyroclastic flows, buried by volcanic mudflows or damaged by ashfall. Even during low level activity sustained gas emissions alter the density and character of vegetation. Volcanic damage to forests can be detected in reflectance and scattering properties extracted from satellite imagery. The rates and processes of recovery following volcanic eruptions have not yet been well-quantified, but have potential as a tool for identifying and assessing the date of past eruptions, independent from geological methods. This project will exploit multi-platform satellite datasets to map extensive and spatially variable changes in forests after volcanic eruptions, with a particular focus on the period of recovery.
This studentship will address the following questions:
• How do major volcanic eruptions affect selected tropical and temperate forest ecosystems? This will be addressed through case studies of major eruptions, for example, the impact of the 2011 eruption of Chaiten, Chile. Significant volcanic impacts to investigate could include the flattening or burial of trees, leaf damage from ashfall, the effect of volcanic gases on vegetation and alteration of drainage/water supply due to topographic change.
• Can the footprint of past eruptions be detected in forests surrounding active volcanoes?
• What factors affect the rate or recovery of temperate and tropical forests after an eruption?
Time series of vegetation change will be mapped in the first instance using indexes derived from optical imagery (e.g., LANDSAT, Sentinel-2), with more quantitative analysis over critical periods using Synthetic Aperture Radar imagery (e.g., Sentinel-1 and higher resolution commercial datasets TSX and CSK where available).
This work will build a new understanding of the characteristics of volcanic impacts on vegetation, and of recovery rates related to different types of volcanic activity. We will test if the spatial extent, nature and intensity of impacts can be interpreted to provide information about past eruption. To do this we will draw on recent events for which pre- and post-eruption satellite imagery are available, as well as looking for longer-term imprints of major eruptions on forest structure.