Abstract ID: 533

Do soil and topography affect wood decomposition in Central Amazon?

Soil factors and topography are predictors of the forest structure and functioning in Central Amazon. Soil and topography explained spatial variation of aboveground tree live biomass and affected the rates of biomass change and nutrient cycles. However, there are no studies testing the relationship between these variables and wood decomposition. Therefore, we carried out an experiment to assess the effects of soil and topography on wood decomposition of four tree species (Manilkara huberi, Couratari guianensis, Hura crepitans and Parkia pendula) with different wood densities (0.86, 0.54, 0.32 and 0.29 g.cm^-3, respectively). A wood sample of each tree species (30 x 5 x 2.5 cm) was deposited in each of the 71 plots spread systematically over 64 km ² of terra-firme forest in Reserva Florestal Adolpho Ducke. After one year (March 2007 to March 2008) we took back the samples to estimate the percentage of decomposed wood. We used multiple regression analyses to test the effects of physical and chemical characteristics of topsoil, aboveground tree live biomass, slope of the terrain and litter on wood decomposition. There were no relationships between the majority of the variables and wood decomposition of the four tree species. Aboveground tree live biomass was related only to wood decomposition of C. guianensis, indicating that wood decomposition of this species may be faster where environmental productivity is higher. In general, soil, topography, aboveground tree live biomass and litter can not be used as predictors of wood decomposition. Models employing soil and topography to improve estimates of carbon fluxes may be limited, since carbon releasing via wood decomposition does not follow the same patterns of biomass production and nutrient cycling.

Session:  Biogeochemistry - Nutrient cycling in forest and savanna ecosystems and agroecosystems.

Presentation Type:  Oral