GC33D-0550:
A global analysis of island pyrogeography
Wednesday, 17 December 2014
Clay Trauernicht, University of Hawaii at Manoa, Natural Resources and Environmental Management, Honolulu, HI, United States and Brett P Murphy, University of Melbourne, School of Botany, Parkville, Australia
Abstract:
Islands have provided insight into the ecological role of fire worldwide through research on the positive feedbacks between fire and nonnative grasses, particularly in the Hawaiian Islands. However, the global extent and frequency of fire on islands as an ecological disturbance has received little attention, possibly because ‘natural fires’ on islands are typically limited to infrequent dry lightning strikes and isolated volcanic events. But because most contemporary fires on islands are anthropogenic, islands provide ideal systems with which to understand the linkages between socio-economic development, shifting fire regimes, and ecological change. Here we use the density of satellite-derived (MODIS) active fire detections for the years 2000-2014 and global data sets of vegetation, climate, population density, and road development to examine the drivers of fire activity on islands at the global scale, and compare these results to existing pyrogeographic models derived from continental data sets. We also use the Hawaiian Islands as a case study to understand the extent to which novel fire regimes can pervade island ecosystems. The global analysis indicates that fire is a frequent disturbance across islands worldwide, strongly affected by human activities, indicating people can more readily override climatic drivers than on continental land masses. The extent of fire activity derived from local records in the Hawaiian Islands reveals that our global analysis likely underestimates the prevalence of fire among island systems and that the combined effects of human activity and invasion by nonnative grasses can create conditions for frequent and relatively large-scale fires. Understanding the extent of these novel fire regimes, and mitigating their impacts, is critical to reducing the current and rapid degradation of native island ecosystems worldwide.
