Tree-Ring Based Reconstruction of Historical Fire in an Endangered Ecosystem in the Florida Keys

Lauren A Stachowiak,Elizabeth A Schneider,Grant L Harley,Hunter A Bonawitz,Savannah A Collins-Key,Maegen L Rochner

doi:10.3390/fire4040079

Abstract

Big Pine Key, Florida, is home to one of Earth’s largest swaths of the critically-endangered dry forests. Known as pine rocklands, this fire-adapted ecosystem must experience regular fire to persist and remain healthy. Pine rocklands are composed of a sole canopy species: the South Florida slash pine (Pinus elliottii var. densa), along with a dense understory of various woody and herbaceous species, and minimal surface moisture and soil development. Slash pine record wildfire activity of the surrounding area via fire scars preserved within the annual tree rings formed by the species. Our study used dendrochronology to investigate the fire history of the pine rocklands on Big Pine Key, specifically within and around the National Key Deer Refuge (NKDR) because it is the largest segment of unfragmented pine rockland on the island. We combined the results found within the NKDR with those of a previous study completed in 2011, and incorporated historical documents and reports of prescribed and natural fires through November 2019 into our evaluation of fire history on Big Pine Key. We conclude that prescribed burning practices are vital to truly restore natural fire behavior, and repeated burning on these islands in the future must be prioritized.

Highlights

Contemporary pine rocklands are dominated by the fire-dependent South Florida slash pine
Evidence of a distinct drop in fire frequency post-1957 is especially important given the concerted efforts of the US Fish and Wildlife Service (USFWS) and various burn partners to ubiquitously employ prescribed fire—even with a stressed social license for fire in the island communities in the presence of the prescribed fire, more fire is necessary if we are to return to a pre-National Key Deer Refuge (NKDR) establishment regime
Short MFI and WMPI values indicate a higher frequency of forest fires, translating to lowerseverity fires

Summary

Introduction

Contemporary pine rocklands are dominated by the fire-dependent South Florida slash pine Densa Little & K.W. Dorman; hereafter slash pine) and have a small natural geographic range. Dorman; hereafter slash pine) and have a small natural geographic range This ecosystem is currently only found in the US in parts of the southern Florida mainland and Florida Keys [1,2,3,4]. The historical presence of fire on Big Pine Key has varied widely and has been used or managed in different ways through time. The paleocharcoal record from Big Pine Key and the region extends the presence of fire in pine rocklands to 4500 cal yr BP [12,13]. Prior to European contact and colonization, fires started by Indigenous people living in pine rocklands were often to protect and preserve key deer

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Conclusion