Mineral Soil Chemical Properties as Influenced by Long-Term Use of Prescribed Fire with Differing Frequencies in a Southeastern Coastal Plain Pine Forest

Thomas Coates,Andrew Johnson,Donald Hagan,James Dozier,Alex Chow,John Keen,Wallace Aust

doi:10.3390/f9120739

Thomas Coates, Andrew Johnson + Show 5 more

Open Access

https://doi.org/10.3390/f9120739

Copy DOI

Abstract

Recent studies suggest increased fire frequency may impair soil chemistry, but few studies have examined long-term effects of repeated, frequent prescribed fires on forest soil properties in the southeastern Coastal Plain, USA. In this study, forest soil chemistry at the 0–10 and 10–20 cm mineral soil depths of sandy surface horizons (Entisols and Spodosols) were compared among units burned 0, 4, 6, and 8 times between 2004 and 2015 and 0 and 20 times between 1978 and 2015 in a longleaf (Pinus palustris Mill.)–loblolly (Pinus taeda L.) pine savanna at the Tom Yawkey Wildlife Center (Georgetown, SC, USA). At the 0–10 cm soil depth, soil pH (p = 0.00), sulfur (p = 0.01), calcium (p = 0.01), iron (p < 0.01), manganese (p < 0.01), and aluminum (p = 0.02) treatment means differed (2004–2015). Calcium and manganese displayed positive, significant relationships and sulfur displayed a negative, significant relationship with increasing fire frequency (p < 0.05). However, correlation of these relationships was low (r2 ≤ 0.23). Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the mean of the unburned compartment, sulfur (p = 0.01) and iron (p < 0.01) were less in soils from the burned compartments. At the 10–20 cm soil depth, soil pH (p = 0.01), manganese (p = 0.04), phosphorus (p = 0.01), potassium (p = 0.02), and iron (p < 0.01) treatment means differed (2004–2015). Potassium displayed a negative, significant relationship and soil pH displayed a positive, significant relationship with increasing fire frequency (p < 0.05). Correlation of these relationships was low (r2 ≤ 0.16), however. Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the unburned compartment, potassium (p = 0.00) and iron (p < 0.01) were less in soils from burned compartments. These results are inconsistent with studies suggesting that forest soil chemistry is substantially altered by increased fire frequency and support other studies from this region that have documented minimal or temporary soil chemical changes associated with frequent prescribed fires.

Highlights

Fire has been a formative force for forest vegetation and soil properties in many ecosystems for millennia [1,2,3]
In light of the paucity of information regarding fire and its potential, long-term impacts on southeastern Coastal Plain soils, despite the widespread use of prescribed fire in the region [31], we evaluated the effects of frequent prescribed fire for forest soil chemistry (0–10 and 10–20 cm soil depths; Spodosols and Entisols) in a longleaf pine-dominated forest located in the southeastern Coastal
Soil Depth 0–10 cm Significance of differences between the treatment means at the 0–10 cm soil depth for 0, 4, 6, and 8 burns from 2004 to 2015 were determined for the following variables: Al (p = 0.02), Ca (p < 0.01), Mn (p < 0.01), S (p = 0.01), Fe (p < 0.01), soil pH (p = 0.00) (Table 1)

Summary

Introduction

Fire has been a formative force for forest vegetation and soil properties in many ecosystems for millennia [1,2,3]. Numerous ecosystem properties and processes are influenced by the time since last fire, or fire return interval [4,5]. In some landscapes, such as the spruce-fir forests of the Adirondack Mountains [6], historic fire return intervals may have spanned several decades prior to. Other locations, such as the southeastern Coastal Plain, are hypothesized to have fire return intervals of two years or less [3] due to both natural and anthropogenic ignitions [7,8].

Methods

Results

Discussion

Conclusion