Science in Recovery: Life History of Euphorbia telephioides, a Threatened Species Endemic to the Florida Panhandle: Are These Data Useful to Evaluate Conservation?

Dr. Vivian Negrón-Ortiz, U.S. Fish & Wildlife Service, Ms. Melanie Kaeser, U.S. Fish and Wildlife Service

To protect and manage species listed under the U.S. Endangered Species Act requires the use of the best available science. Field-based studies on topics such as demography, reproductive biology, and seed ecology have provided sound conservation strategies for many imperiled plants. Unfortunately, understanding of relevant biology is still lacking for numerous rare species. Such biological information was lacking for Euphorbia telephioides, a threatened species primarily endemic to pineland flatwoods in the Florida Panhandle. This species is a perennial herbaceous plant that has suffered from the effects of habitat loss, degradation, and fragmentation throughout the entire range of its distribution in Florida. This is the primary threat identified in the Recovery Plan of 1994, and remains the main threat to date. As part of a longterm study to understand the conservation requirements for the recovery of E. telephioides, three distinct populations were studied across the range of this species. We established one permanent plot in each population, and investigated size and reproduction, response to fire, and in situ seed germination and seedling survival from 2010-2014. Euphorbia telephioides plants are long-lived and survived fire by resprouting. This species is composed of males, females, and monoecious individuals with labile sex expression, a system that has the effect of ensuring outcrossing and thus contributing to genetic variability, but also guarantees pollination in the absence of cross-pollination. To minimize exposure to seasonally stressful conditions, both adults and seedlings exhibited obligate winter dormancy and facultative nonsynchronized summer dormancy as well as prolonged vegetative dormancy. Seeds survive < 1 year, denoting that there is no persistent soil seed bank that can be relied on to maintain populations in the face of environmental stochasticity. However, once seedlings are established in the soil, they resprout back after fire, favoring a hypothesis that seedlings contribute to E. telephioides persistence. In conclusion, E. telephioides displays traits that are part of a life history that is adaptive in the fire-prone habitats where this species occurs. Implications for in-situ and ex-situ conservation programs will be discussed.

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