Impacts of Prescribed Fire Frequency on Coarse Woody Debris Volume, Decomposition and Termite Activity in the Longleaf Pine Flatwoods of Florida

James L Hanula,Dale D Wade,Michael D Ulyshen

doi:10.3390/f3020317

Abstract

Longleaf pine (Pinus palustris) ecosystems have been reduced dramatically throughout their range. Prescribed burning is considered the best way to restore and maintain plant communities associated with longleaf pine, but little is known about its effects on coarse woody debris and associated organisms. We conducted a 5-year study on the Osceola National Forest in northeastern Florida to determine how dormant-season prescribed burns at different frequencies (annual, biennial, quadrennial or unburned) applied over a 40-year period affected coarse woody debris volume, decomposition and nitrogen content, and subterranean termite (Reticulitermes spp.) activity. Burn frequency had no effect on standing dead tree or log volumes. However, freshly cut longleaf pine logs placed in the plots for four years lost significantly less mass in annually burned plots than in unburned plots. The annual exponential decay coefficient estimate from all logs was 0.14 yr−1 (SE = 0.01), with the estimated times for 50 and 95% loss being 5 and 21.4 years, respectively. Termite presence was unaffected by frequent burning, suggesting they were able to survive the fires underground or within wood, and that winter burning did not deplete their food resources.

Highlights

The importance of coarse woody debris (CWD), which includes standing dead trees or “snags” and large-diameter logs on the forest floor, in maintaining forest diversity is widely recognized [1,2,3,4]
Most research on large woody debris and its function in North American forests has been conducted in the Pacific Northwest [2,6], and little is known about this important resource in forests of the Southeastern United States [7]
Since burn frequency had no effect on coarse woody debris volume, we calculated the average volume per unit area using the total volume per plot for the 24 plots

Summary

Introduction

The importance of coarse woody debris (CWD), which includes standing dead trees or “snags” and large-diameter logs on the forest floor, in maintaining forest diversity is widely recognized [1,2,3,4]. Most research on large woody debris and its function in North American forests has been conducted in the Pacific Northwest [2,6], and little is known about this important resource in forests of the Southeastern United States [7]. Longleaf pine (Pinus palustris) forests endemic to the region are of particular interest. These ecosystems once occupied >24 million hectares, but due primarily to harvesting, wild hogs, conversion to species with faster juvenile growth, and land use changes, less than 1.3 million fragmented hectares remained by the mid 1990’s [8]. News of the impending demise of this species sparked a widespread, concerted effort by virtually all southern federal and state agencies, non-government natural resource organizations, and ecologically oriented private land owners to reverse the decline

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