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Pinus elliottii var. densa Little and Dorman
Common Name: South Florida slash pine, Dade County pine

 Distribution: This variety of slash pine is restricted to southern peninsular Florida. The species ranges northward and westward to Louisiana and South Carolina on the coastal plain.

 Habitats: South Florida slash pine grows on thin limestone soils in pine rocklands in Dade and Monroe counties, but on deeper acid soils in south-central Florida. This variety is a dominant in pine flatwoods and xeric sandhills. The typical variety (P. elliottii var. elliottii) is often found on wet sandy soils. South Florida slash pine substitutes for longleaf pine (P. palustris) near the southern end of the range of the latter species. South Florida slash pine is occasional in other plant communities such as Florida scrub and seasonal ponds.

 Life History: South Florida slash pine is a tall (to 40 m), long-lived tree with sparse branches. As a seedling, it has a grass stage that is not as pronounced as longleaf pine but helps distinguish it from the typical variety of slash pine (P. elliottii var. elliottii). However, Wunderlin and Hansen (2000) feel that the two varieties cannot be dependably distinguished. Slash pine trees grow rapidly and begin to produce cones at 10 years. South Florida slash pines of all sizes can survive low intensity fires, using a combination of a protected buds in the grass stage, thick bark, and rapid shedding of lower branches (Little and Dorman 1954). Nonetheless, south Florida slash pine mortality may be high in high intensity fires. Fire-caused mortality in P. elliottii var. elliottii (which lacks the fire-adapted traits of south Florida slash pine) is typically high.

 Phenology: Male and female cones are produced in the spring. Large cone crops are produced about every 3 years.

 Breeding System and Pollination: South Florida slash pine is wind pollinated.

 Genetics: We are not aware of any genetic studies on south Florida slash pine.

 Population Dynamics: Populations probably have low mortality rates except when stressed by fire, flooding, or drought. Postfire mortality is highest in areas that have not received prior burning (Menges and Deyrup 2001). Fall burns increase fire intensity, which in turn promotes more intense attacks by bark beetles and higher mortality. Postfire mortality tends to be lowest in areas managed with low intensity winter burns (Doren et al. 1993). Larger areas burned also tended to increase fire intensity and mortality. Fire-induced mortality did not spread to nearby, unburned trees (Menges and Deyrup 2001). However, such spread may occur in northern Florida where more damaging bark beetle species occur.

 Interesting Facts: The wood of south Florida slash pine is extremely hard and resistant to decay. It has been used extensively in building.

 Data Collected by Archbold Biological Station’s Plant Ecology Lab: We have conducted two studies on south Florida slash pine. One (concluded) project focused on mortality patterns with respect to fire following 24 burns (Menges and Deyrup 2001). A second project focused on recruitment, growth, and mortality in relation to flooding in four seasonal ponds. Annual censuses were used to gather demographic data, and biweekly monitoring of surface water depth also occurred.

 Data Availability: Data from Menges and Deyrup (2001) are available on the Web site.

 Contact Person: Eric S. Menges

 References:

1.  Doren, R.F., W.J. Platt, and L.D. Whiteaker. 1993. Density and size structure of slash pine stands in the Everglades region of south Florida. Forest Ecology and Management 59:295-311.

2.  Elias, T.S. 1987. Trees of North America. Gramercy Publishing Company, New York. 948 pp.

3.  Little, E.L. and K.W. Dorman. 1954. Slash pine (Pinus elliottii), including south Florida slash pine. Southeastern Forest Experimental Station Paper No. 36. Asheville, NC.

4.  Menges, E.S. and M.A. Deyrup. 2001. Postfire survival in south Florida slash pine: interacting effects of fire intensity, vegetation, burn size, and bark beetles. International Journal of Wildland Fire 10:53-63.

5.  Wunderlin, R.P. and B.F. Hansen. 2000. Flora of Florida. Volume 1. Pteridopytes and Gymnosperms. University Press of Florida. Gainesville. 365 pp. 

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