Fire history and forest structure of an endangered subtropical ecosystem in the Florida Keys, USA

Abstract

We focussed on the influence of historical fire and varied fire management practices on the structure of globally endangered pine rockland ecosystems on two adjacent islands in the Florida Keys: Big Pine Key and No Name Key. We reconstructed fire history in two stands from fire scars on South Florida slash pines (Pinus elliottii Engelm. var. densa Little & Dor.) that were accurately dated using dendrochronology, and quantified stand structure to infer successional trajectories. Fire regimes on Big Pine Key and No Name Key over the past 150 years differed in fire return interval and spatial extent. Fire scar analysis indicated that fires burnt at intervals of 6 and 9 years (Weibull median probability interval) on Big Pine Key and No Name Key with the majority of fires occurring late in the growing season. On Big Pine Key, pine recruitment was widespread, likely due to multiple, widespread prescribed burns conducted since 2000. No Name Key experienced fewer fires than Big Pine Key, but pines recruited at the site from at least the 1890s through the 1970s. Today, pine recruitment is nearly absent on No Name Key, where fire management practices since 1957 could result in loss of pine rockland habitat.