Abstract:
This study examined nitrogen dynamics in decomposing Quercus prinus L. litter, confined in litterbags, in two tropical forests (La Selva Biological Station, Costa Rica and Luquillo Experimental Forest, Puerto Rico) and one temperate forest site (Coweeta Hydrologic Laboratory, NC). Using regressions of %N in the decomposing litter against litter mass remaining. we demonstrated similar concentrations of N at all sites when the amount of litter lost was 50%. By using naphthalene, an arthropod repellent, we examined the effect of microarthropods on the N fluxes in the litterbags. Microarthropods had little effect on the %N remaining. At La Selva, the presence of fauna resulted in a marginally significant increase in litter nitrogen concentrations (p <0.06). At both tropical sites, there was a significant net immobilization of N followed by N mineralization after four months. Although there was a net immobilization of N at Coweeta, this lasted for a longer period and the litterbags had not begun to mineralize N after 10 months. We suggest that the rapid accumulation of N in decomposing litter at the tropical sites during the first few months after leaf fall can result in the retention of mobile nitrogen ions in soils. The subsequent mineralization, in later decomposition stages, can make N available to trees during leaf hush. (C) 1999 Elsevier Science B.V. All rights reserved.

Author Keywords:
nitrogen, microarthropods, decomposition, tropical soils, vernal dam, tropical-temperate contrasts

KeyWords Plus:
LITTER DECOMPOSITION, MICROBIAL ACTIVITY, SOIL, NAPHTHALENE, LIMITATION, ECOSYSTEM

Addresses:
Heneghan L, De Paul Univ, Environm Sci Program, 2325 N Clifton Ave, Chicago, IL 60614 USA
De Paul Univ, Environm Sci Program, Chicago, IL 60614 USA
Univ Georgia, Inst Ecol, Athens, GA 30602 USA
Univ Puerto Rico, Inst Trop Ecosyst Studies, San Juan, PR 00936 USA

Publisher:
ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS

IDS Number:
252TR

ISSN:
0929-1393