Midwest Fish & Wildlife Conference 2017

AUTHORS: Caleb P. Roberts, Victoria M. Donovan - Department of Agronomy & Horticulture, University of Nebraska-Lincoln; Craig R. Allen, USGS Nebraska Wildlife Cooperative Research Unit; Larkin Powell, School of Natural Resources, University of Nebraska-Lincoln; Carissa Wonkka, Department of Agronomy & Horticulture, University of Nebraska-Lincoln; David G. Angeler, Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences; David Wedin, School of Natural Resources, University of Nebraska-Lincoln; Dirac Twidwell, Department of Agronomy & Horticulture, University of Nebraska-Lincoln

ABSTRACT: Although one of the most-studied systems in the world, relatively little is known of the long-term legacy effects of extreme fire in Ponderosa Pine (Pinus ponderosa) systems. We sought to identify and assess legacy effects of a severe wildfire by contrasting structural and community patterns across a burn severity gradient 27 years post-wildfire. We conducted our study within and adjacent to the burn perimeter of the 1989 Fort Robinson wildfire in Nebraska’s Pine Ridge region. At 56 sampling units across unburned, low severity, moderate severity, and high severity burn patches, we measured structural elements (tree density and coarse woody debris cover) and biological communities (shrub and bird). We detected legacy effects across a burn severity gradient in all observed structural and community elements. For all elements, high severity patches differed from unburned patches. Tree density and bird communities showed similar legacy effects, with distinct patterns between all severity types (P P=0.59). Coarse woody debris cover showed a dichotomous pattern: high and moderate severity patches were similar (P=0.44) but differed from low severity and unburned patches (PPP=0.76). Our study demonstrates that the diversity and heterogeneity fire creates in Ponderosa Pine systems can persist for multiple decades after the fire event. Multiple fires, with a gradient of burn severities, occurring at different times, likely create a shifting mosaic which acts to foster diverse, unique communities and enhance the spatiotemporal resilience of Ponderosa Pine systems across landscapes. To foster long-term structural and community diversity in Ponderosa Pine systems, land managers should allow a range of burn severities and consider the potential impacts of post-fire management practices, such as salvage logging, that may reduce variation amongst patches.