Dissertation Research: Effects of Fires on Population Dynamics and Viability of Chamaecrista keyensis (Caesalpinioideae), An Endemic Herb of the Lower Florida Keys

Florida International University, Miami FL

Investigators

Abstract

In many fire-prone ecosystems of North America, the historical fire regimes have been disrupted for decades, resulting in decline and disappearance of unique species that reside in them. This study will determine the effects of experimental fire regimes on the Big Pine Partridge Pea, Chamaecrista keyensis (Fabaceae), a legume herb that only occurs in pine rocklands of the lower Florida Keys. Lower Keys pine rocklands are one of the fire-dependent ecosystems in Florida, but their historical fire regime is unclear. An ongoing, larger study funded by the Department of the Interior, includes experimental treatments (summer burn, winter burn, and unburned controls) on blocks of pine rockland on Big Pine Key. Within this design are detailed plant population studies, including monitoring soil seed bank dynamics. Preliminary results indicate that the winter burn treatment may be the most beneficial for maintaining or increasing populations of Big Pine Partridge Pea. These seasonal fire treatments are being repeated to see whether this trend holds. This study will also determine the relationship of Big Pine Partridge Pea population dynamics with habitat variables influenced by fire. This research will help to identify the historical fire regimes under which the Lower Keys pine rocklands and their unique species evolved. Results will shed light on the processes that can lead to local population decline and extinction of a rare species.