Effect of fire weather, fuel age and topography on patterns of remnant vegetation following a large fire event in southern California, USA

Abstract

Large fire events in southern California have burned thousands of hectares over the past decade. Landscape pattern and natural system processes are shaped by these large conflagrations, thereby influencing the ecological structure and functioning of the region. Unburned vegetation remnants can be used to assess general fuel consumption and to provide valuable information regarding fire behaviour, weather effects and post-fire regeneration. For this study, post-fire unburned vegetation was mapped at a very fine spatial resolution based on semi-automatic classification of airborne large-format multispectral image data and compared across different fire environment zones within the 2003 Cedar Fire burn perimeter. Landscape metrics were used to characterise unburned vegetation patches for a section of the Cedar Fire affected by Santa Ana weather conditions and for a section of the fire that burned under non-Santa Ana weather conditions. Maps of remnant vegetation and associated landscape metrics were compared across these two sections and within shrubland community type, topography and age-class strata using inferential statistics. Key findings reveal more unburned vegetation in larger, rounder patches in the non-Santa Ana section. Pre-fire stand age greater than 6 years showed little effect on the amount or pattern of unburned vegetation within the Santa Ana section.