DENSITY AND SIZE STRUCTURE OF SLASH PINE STANDS IN THE EVERGLADES REGION OF SOUTH FLORIDA

We measured the density and size-class composition of three south Flor ida slash pine (Pinus elliottii var. densa) stands in Everglades Natio nal Park and Big Cypress National Preserve. These stands differed in f ire management history and in whether or not they had been logged. The density and size-class structure of the unmanaged, unlogged stand (Lo stman's Pines) differed markedly from the density and size-class struc ture in either the fire-managed, unlogged stand (Pines West) or the fi re-managed, logged stand (Long Pine Key). Both the density and number of size classes present were more variable at Lostman's Pines than at Pines West or Long Pine Key. In addition:both larger and smaller trees occurred in stands at Lostman's Pines than at Pines West or Long Pine Key. These data suggest that even in the absence of logging, past fir e management practices have converted an uneven sized, variable densit y stand to an even-sized, uniform density stand. Fire suppression, fol lowed by intense fires during the dry season, was probably responsible for the loss of large trees in non-logged stands such as Pines West. The high densities of pines currently in stands at Pines West and Long Pine Key result in little open space for recruitment, slowing the ret urn to an uneven-aged stand. We propose that restoration of second-gro wth south Florida slash pine stands to uneven-sized, variable density states will require reintroduction of fires more characteristic of pre settlement environments. Sufficiently intense and numerous early wet s eason fires (April-June) are probably the only fires that can thin est ablished trees and thereby open space for recruitment into populations .