Experimental introductions of Florida ziziphus on Florida’s Lake Wales Ridge, USA

Summary

Florida ziziphus (Ziziphus celata), Endangered and known from fewer than a dozen genetically depauperate populations along a 45 km stretch of Florida's Lake Wales Ridge, mostly on private cattle pasture with only two publicly protected sites, was the subject of two experimental introductions by Archbold Biological Station testing transplants against direct seeding as restoration methods. In June 2002, 144 potted plants and 1,728 seeds were introduced across 36 experimental plots at Lake Wales Ridge National Wildlife Refuge under burn-only, chainsaw-and-burn, and untreated control treatments; a second introduction in June 2005 placed 286 potted plants and 3,000 seeds across five sites of varying habitat quality at The Nature Conservancy's Tiger Creek Preserve. Transplants substantially outperformed seeds at both sites: cumulative transplant survival reached 76.4% after 4.5 years at Lake Wales Ridge and 72.4% after two years at Tiger Creek, while the 1,728 seeds sown at Lake Wales Ridge produced only three surviving seedlings (0.17% establishment) and the 3,000 Tiger Creek seeds yielded 47 (1.57%). Transplant growth differed sharply between sites, negligible at Lake Wales Ridge but substantial at Tiger Creek, while seedling survival was nearly five times higher at Tiger Creek than Lake Wales Ridge, suggesting real differences in microsite or propagule quality between locations. Major difficulties included limited genetic and mating-type diversity constraining seed production, slow and uncertain seed-based propagation, and transplant shock and animal disturbance. The project rates itself Partially Successful, since transplant survival exceeded 70% but introduced plants had not yet flowered, leaving reproductive viability of the new populations unconfirmed.