Fire Ecology, 2008
Volume 4, Issue 2
Indirect Effects of Fire Severity on Avian Communities in Ponderosa Pine and Aspen Forests in Western North America: A Review
Authors: Kerri T. Vierling and Leigh B. Lentile
Fire is a highly dynamic process, annually affecting large expanses of western forests (Allen et al. 2002, Morgan et al. 2003, Schnoenagel et al. 2004, Westerling et al. 2006). Even large, severe wildfires create heterogeneous effects across the landscape, and scientists use burn severity classifications to infer fire effects on soil and vegetation, potential successional trajectories, and rates of ecosystem response following fire (Jain et al. 2004, Lentile et al. 2006). However, the ecological implications of severity are variable within and across ecosystems and definitions vary among user groups, complicating the broad-scale interpretation of severity. Severity assessments tend to be qualitative and often fail to specifically identify how each severity level affects overstory or understory vegetation components, soil, erosion potential, or other habitat attributes (Lentile et al. 2006, Lentile et al. 2007).Broad-scale burn severity assessments require remote measurement of surface properties that can be mechanistically related to ground measures of post-fire ecosystem condition and used to predict likely trajectories of vegetation change (Smith et al. 2007). Scientists use severity mapping for multiple objectives related to post-fire project planning and monitoring, and research exploring relationships among pre-fire, mid-fire, and post-fire characteristics and response. Lawyers and politicians use severity information as evidence in legal debates surrounding post-fire timber salvage or restoration activities (Lentile et al. 2006). Despite the accessibility of satellite data and the utility of severity mapping, Stephens and Ruth (2005) noted that the only wildland fire data recorded as late as 2004 on Forest Service lands were total area burned, fire location, and the dominant vegetation types within the fire perimeter. Remotely sensed data provide managers the ability to answer many questions about immediate and long-term ecological change, particularly whether fire effects are less severe in areas where they applied fuels treatments. For this reason, Stephens and Ruth (2005) suggested that fire severity information (unchanged, low, moderate, and high) be recorded for all large forest fires. However, any determination of fuels treatment effectiveness must be placed in the context of the local fire regime.