Oak-saw palmetto scrub burned historically in periodic, intense fires that maintained a shrubland vegetation structure that is critical to the habitat requirements of many threatened and endangered species. Landscape fragmentation and fire suppression resulted in much scrub becoming dense, low canopy forests that became difficult to burn under prescribed conditions. Combinations of mechanical treatments and burning have been used since 1992 on Kennedy Space Center/Merritt Island National Wildlife Refuge to restore scrub vegetation with the intention that burning be used after a one-time treatment to maintain the vegetation.
Twenty-eight scrub sites have been monitored before and for varying lengths of time after restoration using 306 15 m line-intercept transects. General trends observed throughout these data are that: 1) scrub oaks and ericaceous shrubs sprout and grow after cutting and burning similar to that after burning only; 2) cover of saw palmetto (Serenoa repens) is reduced by mechanical treatments and that reduction persists in most cases for many years; 3) height growth in cut and burned scrub equals or often exceeds that in regularly burned scrub; 4) where fuels are uniform, openings do not persist long after cutting and burning; however, openings produced by burning piled fuels persist much longer.
Five sites with up to 62 transects have burned a 2nd, 3rd, or 4th time or have been cut and burned a second time. Transects in these sites have been sampled annually.
Results/Conclusions
In stands cut and burned once and then burned again saw palmetto returns to its cover preceding the second burn within about one year. However, this is lower than the cover of saw palmetto before the original mechanical treatment and fire. Sprouting of oaks and ericaceous shrubs after second burns is similar to that after the first set of treatments. Height growth, reestablishment of total cover, and reduction in bare ground are similar after a 2nd burn. In some sites height growth may be less vigorous after a 3rd or 4th burn. Reestablishment of cover of Quercus geminata but not Q. myrtifolia appears to be slower after 2nd or 3rd burns on some sites. A second application of cutting or chopping further reduces the cover of saw palmetto, at least on some sites; the extent of reduction may depend on the details of the mechanical treatment. Prescribed burning of restored scrub stands is generally successful in maintaining height and species composition, reestablishing openings remains difficult.