Timing and Patterns of Size, Reproduction, and Seed Germination in Florida Endemic Euphorbia telephioides (Euphorbiaceae): Management and Conservation Implications

Abstract

To protect and manage species listed under the US Endangered Species Act requires knowledge of the species' biology. Biological information was lacking for Euphorbia telephioides, a threatened species endemic to pine flatwoods in the Florida Panhandle. Decline of this species is due largely to habitat loss and degradation. To understand the conservation requirements for the recovery of E. telephioides, we established three permanent plots, marked 150 plants, and investigated size and reproduction, response to fire, and in situ seed germination and seedling survival from 2010 to 2014. Plants are long-lived and survived fire by resprouting. Populations are composed of vegetatives, males, females, and monoecious individuals with labile sex expression, including fire-induced sex change. Both adults and seedlings exhibited obligate winter dormancy and facultative non-synchronized summer dormancy, and some adults had prolonged (>1 y) vegetative dormancy, which minimize exposure to stressful conditions. Reproductive plants tended to be larger than vegetatives, but did not differ significantly in most size parameters. Seeds possess a deep physiological dormancy, tolerate fire, and persist in the field less than 1 y; thus, soil seed bank is unlikely to maintain populations in the face of environmental stochasticity. Once established, seedlings resprout after fire, which likely contributes to population persistence. Overall, E. telephioides displays life history traits that are adaptive in the fire-prone habitats where this species occurs. For specific management recommendations in the field, knowledge of gender expression and lability, seed ecology, and the effects of disturbances such as fire on plants and habitat are imperative.