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

在北美许多容易发生火灾的生态系统中，历史上的火灾制度已经被破坏了几十年，导致居住在其中的独特物种减少和消失。本研究将确定实验火灾制度对大松鹦嘴豆的影响，Chamaecrista keyensis（豆科），一种豆科草本植物，只生长在佛罗里达群岛下游的松树岩地。下基斯松林是佛罗里达州依赖火灾的生态系统之一，但其历史火灾情况尚不清楚。由内政部资助的一项正在进行的更大规模的研究，包括在大松岛的松岩地上进行实验性治疗（夏季烧伤、冬季烧伤和未烧伤对照）。在这个设计中有详细的植物种群研究，包括监测土壤种子库动态。初步结果表明，冬季焚烧处理可能是维持或增加大松鹧鸪豌豆种群的最有利措施。这些季节性火灾处理正在重复进行，以观察这种趋势是否会持续下去。本研究还将确定大松鹧鸪豌豆种群动态与受火灾影响的生境变量之间的关系。这项研究将有助于确定下基斯松岩地及其独特物种进化的历史火灾制度。研究结果将揭示导致当地种群数量下降和稀有物种灭绝的过程。

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.