Frock, Catherine F. 2015. Microhabitat conditions rather than landscape patterns affect post-dispersal seed removal in burned and unburned lodgepole pine (Pinus contorta var. latifolia) forests. MS Thesis, University of Wisconsin-Madison.

In many landscapes, disturbances create spatial variation at multiple scales and alter wildlife habitat in ways that may influence animal behavior. Small mammals may respond to disturbance patterns, and because many are seed predators, their foraging behavior can influence seed supply and thus plant establishment. Although well studied in other systems, effects of disturbance on spatial patterns of seed removal by small mammals in western North American conifer forests are generally unknown. We conducted a seed removal study in lodgepole pine (Pinus contorta var. latifolia) forests of Greater Yellowstone (Wyoming, USA) to answer two questions: (1) How do seed removal and small mammal abundance vary between recently burned and adjacent unburned forests and with distance from fire perimeter? (2) Within burned and unburned forests, which environmental variables explain variability in seed removal and small mammal abundance? We established 80-m transects (n = 23) centered on and perpendicular to the edge of recent (2012 and 2013) stand-replacing wildfires during summer 2014. Each transect included four stations, with one station established near (10 m) and far (40 m) from the fire’s edge in both burned and unburned forest. Lodgepole pine seeds (1.0 g, ~259 seeds) were supplied in a tray at each station and left in the field for 28 days. Habitat structure and seed abundance were quantified at each station; wildlife cameras were deployed at a subset (n = 33) of stations. Upon retrieval, cameras and remaining seeds were returned to the laboratory for processing. Seed removal averaged 85% across all stations (15% of supplied seeds remained in trays as intact seeds), and evidence of in situ seed consumption (seed hulls) was found in 99% of trays. Small mammals (mice or voles, chipmunks, and squirrels) were the most abundant animals captured by cameras. Seed removal and small mammal abundance did not differ between burned and unburned forests or with edge distance, but both varied with local coarse woody habitat. Seed removal was high in burned and unburned forests at both distances from fire edge, and small mammals were not deterred from using forests one to two years after stand-replacing fire. If observed seed removal rates represent natural conditions and removed seeds are either consumed or relocated to unsuitable germination sites, animal foraging could influence post-fire recruitment of a widespread foundation tree species.