PARENT SESSION
Poster Session 10: Restoration and Adaptive Management
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Oak savanna canopy response to fire suppression and management.

Wolf, Joy¹, ¹ University of Wisconsin - Parkside, Kenosha, WI, USA

ABSTRACT- We assessed the structure and composition in oak (Quercus macrocarpa)savanna canopies as they related to different burn frequencies to understand the range of variability in oak openings. In fire-free years, available resources create opportunities for regeneration. To determine the effect of frequency on canopy structure, dendrochronology was used to construct age and size classes in levels of burned and unburned oak openings. Results varied between sites, but age-size correlations were more similar with less burning (5-6 yr intervals). In the burned sites, r² values ranged from 0.72 with a higher frequency (1-2 years, N=128) to 0.44 with a lower frequency (5-6 years, N=262). With no burning, the r² value was lower (r²=0.39, N=320). While all sites had high oak regeneration; the size structure in a frequent burn or no burn were similarly bimodal (96% in <10 years, 4% >150 years); however, their age structures differed. Higher frequency did not allow young or middle aged cohorts (>10 years) to survive. With no fire, three age cohorts developed (<5, 15-30, >150), with high middle-aged oak mortality (11% of oak canopy) due to shade tolerant species competition (Prunus serotina, Carya, Acer negundo) (oak=29% of canopy in unburned versus >80% in burned). Less burning created more size and age cohort categories (<5 years, 11-35 years, and >150 years). Thus, a higher age to size correlation does not reflect the longer fire-free gaps needed for regeneration. This study illustrates how fire frequency affects age and size dynamics within the same landscape and that moderate intervals of fire occurrences create the highest number of age cohorts with low oak mortality.

Key words: oak savanna, canopy structure, restoration, dendrochronology