Comparing the Effects of Prescribed Burning on Soil Chemical Properties in East Texas Forests with Longleaf and Other Southern Pines in the Overstory

Little has been reported on the effects of repeated prescribed burning on southern United States’ forest soils, especially when site preparation is not the prescribed fire objective. This study was aimed at identifying any correlations between the soil chemical properties among differing burn intervals and the effects prescribed burning has on them. Sampling was performed in 36 plots at three sites with two different burn intervals (2–3 years and biannually) and measured properties: (1) pre-burn (before the fire), (2) post-burn (one month after the fire), and (3) at vegetation green-up (three months after the fire). Sites varied by overstory species with longleaf pine (Pinus palustris) and shortleaf pine (Pinus echinata Mill.) in the overstory on one site, a mix of loblolly pine (P taeda L.) and shortleaf pine on another, and longleaf and loblolly pines on the third. SAS was used to determine the effects of prescribed burning between different time spans (pre-burn to post-burn, post-burn to green-up, and pre-burn to green-up) and between the two different burn intervals. We found that there could be short-term responses in soil chemical properties from repeated burning treatments including nitrogen in the forms of ammonium and nitrate, the carbon-to-nitrogen ratio, and electrical conductivity, all of which decreased following fire regardless of overstory species.