A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

COARSE WOOD DEBRIS DEPOSITION, DECOMPOSITION, AND NUTRIENTRELEASE IN A SELECTIVELY LOGGED FOREST IN CENTRAL AMAZONIAPercy M. Summers; Flávio J. Luizão & Niro Higuchi. INPA-Ecology and Forestry. E-mail:fluizao@inpa.gov.brThe study aimed to assess the possible consequences of large inputs of new coarsewoody debris (CWD) to the current stocks in “terra-firme” forests in Central Amazonia as aresult of selective logging. It focuses on nutrient and carbon cycles, in three permanentplots (4 ha each) of undisturbed forest and four permanent plots that were selectivelylogged, all located 80 km north of Manaus, Brazil. Dry necromass stocks, decomposition,and nutrient stocks and fluxes were determined for all dead wood in the undisturbed plots.The use of permanent plots that have been measured since 1980 allowed to determine thespecies and decomposition time (in years) for the different logs. The mean stock of deadwood mass in the undisturbed forest was 29.7 ± 12.2 Mg ha -1 , increasing up to 80 Mg ha -1after logging. Decomposition rates were estimated using a simple exponential model(OLSON, 1963) for density, k d = 0.074 and for mass, k m = 0.020. Among the factorsaffecting decomposition rates, species, initial density and soil contact were significant(p