KSC and Merritt Island National Wildlife Refuge (MINWR) have collaborated on scrub restoration and monitoring since 1992. Scrub restoration is directed towards improving habitat conditions for the Florida scrub-jay. KSC/MINWR supports a core scrub-jay population important to the species survival. Fire suppression (1962-1981) and landscape fragmentation allowed some scrub to reach size structure that was fire-resistant under prescribed burning conditions. Unburned scrub becomes unsuitable as scrub-jay habitat, and demographic success declines even if the habitat is still occupied.

Areas that had the potential to be optimal habitat but could not be restored by prescribed burning alone were selected for restoration. Mechanical treatment combined with prescribed burning was used to restore vegetation structure that could then be maintained by prescribed burning. Mechanical equipment and techniques used include Brown tree cutter, V-blade, K-G blade, Kendall tree cutter, and roller-chopper. Sites were burned within about 6 months of cutting. Vegetation was monitored using permanent 15-meter transects established before treatment and sampled periodically after cutting and burning. The responses of scrub vegetation to mechanical treatment and burning were compared to burning only using data from transects in scrub in Happy Creek that burned in 1986 and were sampled at least annually thereafter. Data shown here are illustrative of a large amount of data from numerous sites.

Scrub height in restoration stands in Happy Creek (Stand 3, N = 5; Stand 5, N = 7) and Shiloh (Stand 1, N = 10; Stand 6, N = 10) exceeded considerably the height of periodically burned scrub before treatment. Height growth of cut and burned scrub equaled or exceeded (sometimes by 50 percent or more) that of scrub burned without mechanical treatment (figures 1a and 1b). Regrowth of oaks and ericads was similar between cut/burned and burned-only stands.

Mechanical treatment reduced saw palmetto cover (figures 1c and 1d). In burned stands, saw palmetto cover returned to preburn values within 1 year and remained at those levels. Saw palmetto cover in cut/burned stands was still reduced 7 to 8 years postburn (figures 1c and 1d). Figure 2 shows the treatment and recovery of one transect in the Happy Creek study site.

With careful application, these techniques can produce acceptable vegetation recovery. All mechanical treatments cause some decline in saw palmetto cover. Saw palmetto is the most flammable element in scrub of Merritt Island, and excessive loss can reduce the ability to burn the scrub in the future. Lack of fuel continuity can result in fires no longer spreading through sites, degrading habitat quality. The growth rates of long-unburned scrub after restoration suggest that restored scrub may have to be burned on relatively short intervals during a restoration period. Thus, it is critical to retain the ability to burn scrub frequently. In the historic landscape, openings in scrub were common, but they disappeared during decades of fire suppression, and prescribed burning has not reestablished openings in many landscapes. Where fuels are uniform, regrowth may be dense with no persisting openings. Piled fuels produce local hot spots that kill the roots and rhizomes of sprouting species. These openings close slowly from clonal growth of oaks and ericads. Such strategies should be used with care, because it is also important that the scrub matrix burn in order to top-kill shrubs, reduce litter and duff, and volatilize and recycle nutrients.

Contact: Dr. W.M. Knott (William.Knott-1@ksc.nasa.gov), YA-D3, (321) 867-6987
Participating Organizations: Dynamac Corporation (P.A. Schmalzer and T.E. Foster) and Merritt Island National Wildlife Refuge (F.W. Adrian)