Nitrogen Transformations Following Tropical Forest Felling and Burning on a Volcanic Soil
1987
Matson, P. A. (Pamela A.) | Vitousek, Peter M. | Ewel, John J. | Mazzarino, María Julia | Robertson, G. P.
We measured nitrogen transformations and loss following forest clearing in a relatively fertile tropical forest site. Nitrogen mineralization, nitrification, and amounts of ammonium and nitrate increased substantially in surface soils during the 6 mo following burning, then returned to background levels. The nitrogen content of microbial biomass declined to half its original value 6 mo after clearing and remained low in the cleared sites. Plant uptake of nitrogen was substantial on cleared plots (50 g/m²), but it accounted for only 18% of ¹ ⁵N label added to field plots. Microbial immobilization of ¹ ⁵N was small relative to that in a cleared temperate site, and measurements of denitrification potentials suggested that relatively little mineralized nitrogen was lost to the atmosphere. Substantial amounts of nitrogen (40—70 g/m²) were retained as exchangeable bound nitrate deep in the soils of a cleared plot on which revegetation was prevented; this process accounted for 12% of the ¹ ⁵N label added to field plots.
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