Archbold Biological Station
Biennial Report 1995-1996
P.O. Box 2057 Lake Placid, Florida 33862 USA
Phone: 863-465-2571 FAX: 863-699-1927
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Fire Ecology: Dynamics & Restoration of Old Growth High Pines
Project Director: Ronald
L. Myers, The Nature Conservancy
"High Pine" is a synonyms for sandhill pine savannas and woodlands characterized by longleaf pine, turkey oak, and wiregrass. The sandhill pinelands of Archbold's original property support relict old growth stands of south Florida slash pine, longleaf pine, and sand pine. These stands escaped logging and turpentining and probably reflect the influence of historic fires. These slash/longleaf pine stands, with evergreen and deciduous hardwoods, form a community described as "Southern Ridge Sandhill" (SRS) or "Yellow Sand Scrub." Studies were begun in 1982 to determine the formative fire regime of this unusual sandhill association.
In 1983, all pines on a 9-ha grid (and hardwoods on 1 ha) were mapped, tagged, and aged. The oldest slash pines were 160 years; the oldest longleaf was 220 years. Fire history from a limited number of fire scars showed a mean return interval of 9 years for the 35 years before 1927. Since 1983, mortality and recruitment of pines have been monitored annually. Results suggest; a 160-year maximum age for south Florida slash pine on this site, a steady invasion of sand pine from adjacent scrub, a marked decline in turkey oak abundance, and no recruitment of longleaf pine for 50 years. In 1993 (yr 10 of the study), diameter measurements were repeated on all tagged trees. For most older trees (>100 yr) diameter growth was negligible or negative, suggesting that a loss of photosynthetic capacity from needle scorch after fire would severely stress older trees. Background information was gleaned from; 1927 and 1933 photos, 1932 data compiled by Resident Engineer Alexander Blair on woody vegetation, age structure of the three pine species, fire scars, and knowledge/inferences about plant life histories and community dynamics. This led to a transition model where SRS is a transition between sand pine scrub and high pine communities reflecting a long (60 yr) fire-free interval. Historically, SRS may have been a dynamic ecotone between high pine and scrub vegetation. Depending on the fire regime, returning fire to this transitional association would have at least three outcomes: 1) sand pine scrub/oak scrub, 2) xeric oak woods, or 3) slash/longleaf pine/turkey oak high pinelands; but fire would not maintain the structure and composition of the extant association.
In 1993, fire was re-introduced to the 9-ha study area so as to limit slash/longleaf pine mortality yet over time restore the site to "high pine" (see above). A second fire occurred in 1996. The objectives are to 1) test a pathway of the transition model, 2) illustrate the applicability of fire regime concepts to this and to ecologically analogous landscapes elsewhere (e.g. northern Mexico, California, coastal Carolinas, Australia), and 3) demonstrate fire applications for restoring/maintaining these associations.
Fire applications have involved 1) timing of burns and 2) designing ignition patterns that maximize hardwood topkill yet minimize pine crown-scorch, and maximize fuel consumption while limiting heat damage to the bole and surficial roots of the pines. Both fires were low intensity, causing little mortality to larger pines. In the near-term, burns will continue on a 2-3 year interval, focusing on the growing season. Eventually the fire-free interval will be increased to allow pine regeneration. This restoration effort may help the design of recovery/restoration-phase burn regimes for similar long-unburned high pine.
Lohrer, F.E . (Editor). 1998. Archbold Biological Station, Biennial Report
1995-1996. Archbold Biological Station, Lake Placid. 62 pp.
© Archbold Biological Station, 1998, October.
Webmaster: Fred Lohrer.