PARENT SESSION
Friday, August 11, 8:00-11:30 am
COS 115 - Shrub and woodland ecology
L-14, Lobby Level, Cook Convention Center
Presiders: K Haskins and S Saha

Gapology in Florida scrub plants: occurrence, diversity, and gap properties.

Menges, Eric^*,1, Wally, Alaa², Salo, Jessica ¹, Zinthefer, Robin¹, Weekley, Carl ¹, ¹ Archbold Biological Station, Lake Placid, FL² SUNY Cortland, Cortland, NY

ABSTRACT- Gaps within a matrix of dominant vegetation are important structural features of many ecosystems and provide key microhabitats for subordinate or ephemeral species. In Florida scrub, a fire-dependant shrubland, we investigated plant species occurrence and diversity as a function of gap area, matrix type, and time-since-fire in 805 gaps at 28 sites. We defined gaps as areas free of tall (50 cm) shrubs. Matrix type was characterized by palmettos and scrub oaks in the early years post-fire, but became increasingly dominated by Florida rosemary after 10 years. Gap areas were lognormally distributed but, unexpectedly, did not generally decrease with time-since-fire. Species diversity and richness increased with increasing gap area. The largest gaps were characterized by higher diversity at the edge rather than in the center, a trend driven by common species that are often found under canopy or in litter in gap edges. High species richness was associated with intermediate time-since-fire intervals (6-31 years). As time-since-fire increased, gaps were increasingly dominated by litter and lichens while displaying a decrease in bare sand, herb cover, and herb diversity. For 14 species occurring in 25-79% of gaps, 13 had increased occupancy with increasing gap area, and gap area was the strongest predictor of the occupancy for seven species. Time-since-fire was the strongest predictor of occupancy for five species. This study suggests that gap area and fire cycles are only loosely coupled, and that gap properties (independently of fire) have strong influences on species assemblages in Florida rosemary scrub gaps.

Key words: microhabitat, shrubland, plant community ecology