OOS 17 - Altered Fire Regimes and Dispersal into Post-Fire Landscapes

Wednesday, August 14, 2019: 1:30 PM-5:00 PM
M104, Kentucky International Convention Center
Organizer:
Nathan Gill
Co-organizer:
Monica Turner
Moderator:
Monica Turner
The frequency, size, and severity of stand-replacing fires (which kill trees and initiate secondary succession) are increasing worldwide. Large, high-severity fires have burned recently in the western conterminous US, western Canada, Alaska, Australia, Portugal, and Greece. As rates of change in environmental drivers continue to accelerate, there is high uncertainty about successional trajectories following stand-replacing fire. The fate of obligate seeders (e.g., conifer trees) is especially unclear, and understanding patterns and controls on seed dispersal is fundamental to projecting the composition and structure of post-fire forests. Dispersal from ex situ sources is required for such taxa, but dispersal success may change along with fire regimes and climate. Although dispersal has been well studied within ecology, many questions remain about how dispersal plays out in recently burned forests given changing fire regimes in real-world burned landscapes. This session will focus on stand-replacing fires in forests where the role of ex situ dispersal will be most pronounced in determining postfire stand trajectories. Speakers will consider how dispersal is affected by increased fire frequency, size, and severity, and how climate warming may influence the timing, abundance, arrangement, delivery vector, and ultimately establishment and survivorship of dispersing propagules. Multiple dimensions of dispersal will be covered, including propagule sources (e.g., seed supply); environmental context (topography, patch size, distance to seed source); surface roughness within burned area (e.g., density and size of fire-killed snags); and interactions with other organisms (e.g., seed dispersers or predators). Questions will include: How are animal behaviors (dispersal and predation) sensitive to fire regime change? How is climate change altering seed supply? How much area in recent fires is beyond known dispersal distances? If young forests reburn before they recover, how do seed supply and release height influence dispersal success? How do topographic context and the density and size of postfire snags influence dispersal distance? Are interspecific interactions likely to enhance or reduce seed dispersal? This session will emphasize dispersal mechanisms given novel conditions and identify pressing questions that remain to be answered about dispersal into postfire landscapes.
1:30 PM Cancelled
OOS 17-1
Dispersal ecology: The big picture. A global perspective on the importance of dispersal (widthdrawn)
Fiona J. Thomson, Department of Conservation
1:50 PM
Animals as seed dispersers: Avian seed dispersal in post-fire landscapes
Diana F. Tomback, University of Colorado Denver; Elizabeth R. Pansing, University of Colorado Denver
2:10 PM
Loss of biotic resistance conferred by rodent herbivores and high propagule pressure promote invasive grass-fire cycles
Samuel B. St Clair, Brigham Young University; Tara B.B. Bishop, Brigham Young University; Richard A. Gill, Brigham Young University; Brock R. McMillan, Brigham Young University
2:30 PM
When dispersal fails to be followed by establishment: An example which has implications for patch dynamics
Edward A. Johnson, University of Calgary; Anzala Murtaz, University of Calgary
2:50 PM
The role of patch dynamics in perpetuating fire-maintained longleaf pine savannas
Kevin Robertson, Tall Timbers Research Station; William J. Platt III, Louisiana State University; Maria Paula Mugnani, University of Florida; Charles Faires, Yale University
3:10 PM
3:20 PM
Reduced seed dispersal may erode subalpine forest resilience when young forests reburn
Nathan Gill, University of Wisconsin-Madison; Tyler J. Hoecker, University of Wisconsin-Madison; Monica Turner, University of Wisconsin, Madison
4:20 PM
How does spatial heterogeneity in recent burned areas function to facilitate persistence and migration of Pinus spp. in the Madrean Sky Islands?
Sandra Haire, Haire Laboratory for Landscape Ecology; Miguel L. Villarreal, U.S. Geological Survey; Citlali Cortés Montaño, Independent Researcher; Aaron D. Flesch, University of Arizona; M. Socorro Gonzalez-Elizondo, Instituto Politécnico Nacional; José M. Iniguez, USDA FS; José Raúl Romo León, Universidad de Sonora; Jamie S. Sanderlin, U.S. Forest Service
4:40 PM
The origin of novel tree species assemblages: Mechanisms of forest reorganization with changing climate and disturbance
Winslow D. Hansen, Cary Institute of Ecosystem Studies; A. Park Williams, University of California Los Angeles; Rupert Seidl, University of Natural Resources and Life Sciences (BOKU) Vienna