Dry White Sand Scrubs
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Description
Dry white sands scrub vegetation (State 1) is predominantly dense growths of scrub oaks (myrtle, Chapman’s and sand live oaks) and palmetto (saw and scrub palmetto). In addition, the presence the clonal sandhill oak (Quercus inopina) is a diagnostic feature of Central Florida white sands scrubs. A sparse canopy of sand pines may be present or absent, depending on seed source and fire disturbance frequency.
Herbaceous ground cover of State 1 scrubs is very sparse or completely absent. Where present, it is patchily distributed in openings among scrub oaks. The diversity and density of herbaceous plants are highest in the years immediately following fire, gradually decreasing as oak growth dominates (Menges and Hawkes 1998).
Description
State 2 describes late successional vegetation resulting from long term fire suppression (>100 years) of former scrub (FNAI, 2010). Xeric hammocks are compositionally similar to State 1 white sands scrub in that the same clonal oak species are dominant. However, xeric hammock is a forest with a closed canopy of sand live oak overtopping lower growths of clonal scrub oaks and hardwood seedlings. Sand pine is either absent, having failed to regenerate under densely forested conditions, or is present as a few old emergent trees.
The mid- and under-story strata are overwhelmingly dominated by scrub oaks and palmetto. Other shrubs are sometimes irregularly distributed, including rusty staggerbush (Lyonia ferruginea), sparkleberry (Vaccinium arboreum), deerberry (V. stamineum), garberia (Garberia heterophylla), and Florida rosemary (Ceratiola ericoides). The forest floor is covered with oak leaf litter which holds considerable moisture, creating mesic conditions at ground level and further depressing native herbaceous growth as well as pine germination (FNAI, 2010).
Description
This state describes a restored shrubland with similar structure and ecological function to that of native white sands scrub. Notably, this state describes conditions where native propagules have been extirpated following long term fire suppression and/or extensive soil disturbance associated with commodity land uses, followed by artificial establishment of native clonal oaks and other scrub shrub species. Many native species are absent, and weedy or residual non-native species may persist in this restored scrub community. Herbaceous species are absent, weedy or non-native, depending on pre-restoration conditions and geography.
Restoration of native oaks provides fuels for infrequent fires necessary for ecological functioning and dynamics. Once established, clonal oaks may provide habitat suitable for establishment of other native plant populations, either from artificial seeding or natural recruitment.
The full complement of scrub species composition remains incomplete in State 3. Perennial grasses and forbs with seed dispersal mechanisms not conducive to colonization of distant and disturbed sites are notably absent (i.e. big seeded species which rely on animal and gravity dispersal, and long lived clonal species). However, over time, native scrub plants may recolonize, particularly wind-dispersed native herbaceous species.
Description
This state describes commodity land uses of this concept. Due to their infertility and doughtiness, agriculture and timber production is limited on these white sand soils.
Description
State 5 describes a condition where one or more noxious non-native plant species has invaded and dominated the site. By far the most common invasive plant species is cogongrass (Imperata cylindrica; (MacDonald, 2004)). This highly clonal grass spreads rapidly by underground rhizomes and windblown seeds, forming dense circular patches which can become very large (on the order of 100’s of acres). Cogongrass grows vigorously in full sunlight and thrives on acidic, nutrient-poor soils and droughty conditions such as those of Astatula and Candler soils (MacDonald, 2004). Furthermore, cogongrass is a prolific seed producer, and readily invades following soil disturbances (Yager, Miller, and Jones, 2010). Once clones are established, rapid cogongrass growth will extirpate native ground cover plant populations. In addition, cogongrass may be allelopathic in some situations (Brook 1989, Bryson and Carter 1993). In general, cogongrass may colonize conditions with plenty of sun exposure and open ground. Soil disturbance is conducive to cogongrass colonization.
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