Soil Acidity in Loblolly Pine Stands with Interval Burning
- Dan Binkley
Prescribed burning of loblolly pine (Pinus taeda L.) stands every 2 yr for 24 yr increased soil pH by 0.3 to 0.9 units. Measurements of total acidity (titratable to pH 8.2) in the forest floor showed about a 14 to 21 kmol H+ ha−1 decrease in burned plots. Burning increased the acid neutralizing capacity per gram of forest floor material, but the reduction in forest floor biomass largely offset the difference. Titration curves indicated that the burned forest floor would require only about 0.6 kmol H+ ha−1 to lower its pH to the level of the control plots. Total acidity in the 0 to 10 cm mineral soil was more variable; one burned plot showed no decrease relative to controls, but a more intensely burned plot decreased by about 95 kmol H+ ha−1. Despite this large reduction in total acidity, titration curves indicated that only 25 kmol H+ ha−1 would lower the pH to the control level. This increase in acid neutralizing capacity is about 50 times the current annual H+ input in rain. However, other major components of the ecosystem's H+ budget would need to be quantified to assess the importance of fire in relation to acid deposition impacts.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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