Restoration of Riverine Forest at Hall Branch on Phosphate-Mined Land, Florida



I describe a 1.5-ha riverine headwater forest (Hall Branch) that was created 11 years earlier on phosphate-mined and reclaimed land near Tampa, Florida, U.S.A. Favorable hydrologic and edaphic conditions were realized, owing to the proper positioning of the project site in an effectively reclaimed landscape. The soil had developed a distinct A horizon and an incipient B horizon. Planted trees, mainly species of Acer, Fraxinus, Ilex, Liquidambar, Magnolia, Persea, Quercus, Taxodium, and Ulmus, shared dominance with short-lived volunteer willows (Salix caroliniana) that had already begun to senesce. The tree canopy exhibited 85% cover, and some trees had grown to 12.5 m tall. Basal area reached 8.31 m2/ha for trees 10 cm or more in diameter at breast height. Ten planted tree species produced seeds and yielded seedlings. The floristic composition over the decade consisted of 22 species of trees and 208 shrubs, vines, epiphytes, ferns, graminoids, and forbs. Thirty-eight non-arboreal species were directly transplanted, others arose from a seed bank in muck that was amended on wetter sites, and the rest volunteered via natural dissemination. The frequency of non-arboreal plants was collectively 98%. Seventy-three species at the restoration site were characteristic of the mature, undisturbed reference ecosystem. A corresponding area within the reference ecosystem contained essentially the same number of species and the same array of life forms. Copious plant reproduction has transformed the planted forest into an intact ecosystem that no longer needs restoration assistance.