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# The Effects of Natural and Human Disturbances on Soil Nitrogen Dynamics and Trace Gas Fluxes in a Puerto Rican Wet Forest

P. A. Steudler, J. M. Melillo, R. D. Bowden, M. S. Castro and A. E. Lugo
Biotropica
Vol. 23, No. 4, Part A. Special Issue: Ecosystem, Plant, and Animal Responses to Hurricanes in the Caribbean (Dec., 1991), pp. 356-363
DOI: 10.2307/2388252
Stable URL: http://www.jstor.org/stable/2388252
Page Count: 8
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## Abstract

We examined the effects of two disturbances (Hurricane Hugo and forest clearcutting) on soil nitrogen dynamics and on the exchanges of N$_2$O, CO$_2$, and CH$_4$ between soils and the atmosphere of a subtropical wet forest in Puerto Rico. The disturbances resulted in prolonged increases in ammonium pools and short-term increases in rates of net N-mineralization and net nitrification. Nitrous oxide emissions increased following both disturbances. The most dramatic increase was observed 4 mo after clearcutting; N$_2$O emissions (109 49 $\mu g$ N/m$^2$-hr) from the cut plot were about two orders of magnitude higher than emissions from the reference plot (1.71 $\mu g$ N/m$^2$-hr). Carbon dioxide emissions from both disturbed plots (mean 102.47 mg C/m$^2$-hr) were about 30 percent lower than the reference (mean 15 1.28 mg C/m$^2$-hr). Soils at all sites were generally sinks for CH$_4$. Methane uptake, however, was suppressed by both disturbances. This suppression may be related to disturbance-induced changes in the nitrogen cycle, as we have previously observed in temperate zone forests.

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