OAK DOME CLONAL STRUCTURE AND FIRE ECOLOGY IN A FLORIDA LONGLEAF PINE DOMINATED COMMUNITY

The structure, development, and response to fire of sand-live oak (Quercus geminata Small) and myrtle oak (Q. myrtifolia Willd.) colonies (domes) were examined in a longleaf pine-wiregrass (Pinus palustris Mill.-Aristida stricta Michaux.) community in Ocala National Forest, Florida. Dome areas ranged from 30 m2 to 1000 m2 and domes achieved heights of up to 10 m. The oak clumps excavated (<2 m tall) were clonal with roots and rhizomes concentrated in the upper 50 cm of soil. In the 3-4 year old clumps excavated (above-ground age), 2/3 of the biomass was located below-ground and 1/3 was above-ground. The proportion of above-ground stems that survived a prescribed burn increased markedly for stems >2 m tall with basal diameters >2.0 cm. Stems averaging >2 m tall in domes >200 m2 in area survived better than those in smaller domes. Oak domes <2 m tall burned back to ground level but resprouted readily from underground rhizomes. Height appeared to be the most important factor influencing oak dome persistence in pyrogenic pinelands, with domes >2 m tall having a high probability of above-ground stem survival and domes >4.5 m tall being nearly fire resistant. Height is positively correlated with dome age and therefore to the period of time needed without fire for tall dome (>4.5 m tall) development. Tall domes present within the pinelands are probably a direct result of approximately 20 years of fire suppression prior to the initiation of regular prescribed burning in the 1950's. Seedling establishment was apparently low in years when fire occurred and the year after but increased in the second, third, and fourth years following burning. Dome distribution, abundance, and height are thus dependent on fire frequency, intensity, and land-use history.