The Magnolia grandiflora-Quercus virginiana Forest of Florida

Abstract

Over most of central peninsular Florida, uplands with iron-stained sandy soils have long been occupied by fire-climax vegetation, a savanna combining Pinus palustris and a ground cover of grasses, mainly Aristida stricta. Evidence is given of the now widespread natural replacement of savanna by broadleaf forest when burning is discontinued. The nature of the climatic climax for such soils is illustrated by an analysis of an old stable stand discovered in a fire-protected location, together with plant lists for late-seral or disturbed stands in similar places. The climax is characterized by a combination of trees with high presence among the stands: Magnolia grandifiora, Quercus virginiana, Q. laurifolia, Caryaglabra, Sabal plametto and Persea borbonia, typifying the Magnolia grandifiora-Quercus virginiana association. As a climatic climax this community defines a zone extending from central peninsular Florida northward an unknown distance into Georgia but not extending westward into the panhandle of Florida. At its northern and western limits the Magnolia grandifiora- Quercus virginiana zone abuts a different but closely related Magnolia grandifora-Fagus grandifolia zone. Fagus and Quercus alba have high percentage presence in the climatic climax of that zone, but are absent from the Magnolia-Quercus virginiana zone. On the other hand, Quercus virginiana and Sabal palmetto do not occur in the Magnolia-Fagus association. Pre- viously the two associations, along with additional upland forests on the Atlantic coastal plain extending as far north as Virginia, have been grouped together as the Southern Mixed Hardwood Forest. The boundaries of the Quercus-Magnolia zone are discussed in relation to aspects of climate.