Biomass and nutrient dynamics associated with slash fires in neotropical dry forests

Kauffman, J. Boone and Sanford Jr., Robert L. and Cummings, Dian L. and Salcedo, I. H. and Sampaio, E. V. S. B. (1993) Biomass and nutrient dynamics associated with slash fires in neotropical dry forests. Ecology, 74 (1). pp. 140-151. ISSN 0012-9658

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Abstract

Unprecedented rates of deforestation and biomass burning in tropical dry forests are dramatically influencing biogeochemical cycles, resulting in resource depletion, declines in biodiversity, and atmospheric pollution. We quantified the effects of defores- tation and varying levels of slash-fire severity on nutrient losses and redistribution in a second-growth tropical dry forest ("Caatinga") near Serra Talhada, Pernambuco, Brazil. Total aboveground biomass prior to burning was 74 Mg/ha. Nitrogen and phosphorus concentrations were highest in litter, leaves attached to slash, and fine wood debris (<0.64 cm diameter). While these components comprised only 30% of the prefire aboveground biomass, they accounted for -60% of the aboveground pools of N and P. Three experi- mental fires were conducted during the 1989 burning season. In these treatments con- sumption was 78, 88, and 95% of the total aboveground biomass. As much as 96% of the prefire aboveground N and C pools and 56% of the prefire aboveground P pool was lost during combustion processes. Nitrogen losses exceeded 500 kg/ha and P losses exceeded 20 kg/ha in the fires of the greatest severity. With increasing fire severity, the concentrations of N and P in ash decreased while the concentration of Ca increased. This indicates greater amounts of these nutrients were volatilized (i.e., greater ecosystem losses occurred) with increasing fire severity. Following fire, up to 47% of the residual aboveground N and 84% of the residual aboveground P were in the form of ash, which was quickly lost from the site via wind erosion. Fires appeared to have a minor immediate effect on total N, C, or P in the soils. However, soils in forests with no history of cultivation had significantly higher concentrations of C and P than second-growth forests. Based upon the measured losses of nutrients from these single slash-burning events, it would likely require a century or more of fallow for reaccumulation to occur. However, current fallow periods in this region are 15 yr or less.

Item Type:	Article
Publisher’s Statement:	Copyright by the Ecological Society of America
ID number or DOI:	10.2307/1939509
Keywords:	biogeochemical cycling; Brazil; Caatinga; carbon; deforestation;fire; nitrogen; nutrient loss; phosphorus; slash-and-burn agriculture; tropical forest; volatilization of nutrients
Subjects:	Q Science > QH Natural history > QH301 Biology
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > School of Earth Sciences and Environmental Sustainability
Date Deposited:	17 May 2017 18:54
URI:	http://openknowledge.nau.edu/id/eprint/2916

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