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SCRUB Ecosystem. Scrub is a community composed of a dominance of evergreen shrubs with frequent patches of bare, white sand With or without a canopy of pines Found on dry, infertile, sandy ridges Scrub is one of the oldest ecosystem types in Florida
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SCRUB Ecosystem • Scrub is a community composed of a dominance of evergreen shrubs with frequent patches of bare, white sand • With or without a canopy of pines • Found on dry, infertile, sandy ridges • Scrub is one of the oldest ecosystem types in Florida • There are several types of scrub depending upon what plant is dominant– rosemary, oak, and sand pine are examples
Scrub • These upland habitats were isolated by water, forming desert-like hilltop islands • Because of this isolation, many species of plants and animals developed unique adaptations to the harsh, dry environment of the scrub lands • From 40 to 60% of the plants and animals in scrub lands are endemic (found only there) and some are so rare that they are threatened or endangered
Endemic scrub species • There are more than 20 species of animals that are listed as rare, threatened, or endangered • These include the Eastern indigo snake, sand skink, mole skink, and several species of insects, especially beetles • Other endemic animals include scrub jay, scrub lizard, blue-tailed mole skink, sand skink, and the Florida mouse • If scrub lands disappear, these animals would probably disappear as well
Scrub • Because scrub (and sandhills as well) is usually high and dry, it is well suited for housing or for agriculture. • Over two-thirds of the original scrub land in Florida has already disappeared and only disconnected patches of scrub remain • Therefore, scrub habitat is considered to be the most endangered of the major ecosystem types in Florida
The role of fire in scrub • The plant community in scrub lands needs occasional, high-intensity fires to grow and regenerate • In the absence of fire, many scrub plants will slowly be replaced by other species that are not adapted to periodic fire • Pines will be unable to regenerate and various oaks may establish • Long term exclusion of fire may eventually result in oak scrub or even an upland hardwood hammock
The role of fire in scrub • Lightning fires occur every 20 to 80 years and burn essentially all of the surface vegetation • This allows the trees and ground plants to regenerate and repeat their cycles • If fires are too frequent, the pines don’t have enough time to mature and are incapable of reseeding after the fire • If fires are infrequent, vegetation builds up, resulting in excessive fuel and a very hot fire difficult to control
The role of fire in scrub • Sand pines require fire to survive. • The cones remain on the tree and sealed shut with sap until the heat of a hot fire melts the sap • This allows the cones to open and release the seeds and establish new seedlings • Wiregrass, an herbaceous groundcover around the edges of scrub ecosystems, needs fire in order to stimulate flowering and seeding
The role of fire in scrub • Infrequent high-intensity fires destroy the tree canopy but allow sunlight to reach the forest floor, aiding in the regrowth of new plants • The hot fires leave behind a nutrient-rich ash that feeds new plants as they re-sprout • Since most vegetation is burned away, little or no competition for nutrients exists and the young pine seedlings are able to establish easily and grow quickly • Scrub habitat regenerates rapidly after most fires
Dominant Plants • Scrubby Oaks • Myrtle oak • Sand live oak • Chapman’s Oak • Rusty Lyonia • Saw palmetto • Rosemary and sand pine may also be present • Smooth Lyonia present on lower elevations
Dominant Plants • Oaks form a dense cover with patchy openings that consist of bare sand and sparse vegetation • Wire grass • Hairsedges • Sandyfieldbeaksedge • Pinweeds • Jointweeds • Deer moss
Dominant plants • On drier ridge crests (higher elevation), rosemary may dominate • Rosemary tends to retain openings between shrubs in contrast to oak-dominated scrubs where vegetation tends to fill in openings with time since fire • Some scrub may also be dominated by sand pine, especially on the highest sandy ridgeline
