Soil respiration in native Cerrado and a pasture in Central Brazil: Seasonal variation and deep soil contribution on total flux
Roberto
Engel
Aduan, Empresa Brasileira de Pesquisa Agropecuária, aduan@cpac.embrapa.br
(Presenting)
Carlos
Augusto
Klink, Universidade de Brasília, CARLOSKLINK@aol.com.br
Eric
Atlas
Davidson, The Woods Hole Research Center, edavidson@whrc.org
Soil respiration is perhaps one of the most important in the many different processes of the carbon cycling in natural and cultivated ecosystems. The aim of this study was to measure intensively the soil respiration fluxes in two native Cerrado vegetation types, that differ in tree density (cerrado denso and cerrado stricto sensu) and one planted pasture, measuring total annual fluxes and their seasonal variation. The effect of environmental variables (temperature and rainfall) and the role of deep soil on superficial emissions were also assessed. The native Cerrado ecosystems are located in the Reserva Ecológica do Roncador (RECOR/IBGE), in Brasília, DF, Brazil, while the planted pasture (Brachiaria brizantha) is located in the experimental fields of Embrapa-Cerrados, in Planaltina, DF, Brazil. Soil respiration was measured with the dynamic chamber IRGA technique. Deep soil fluxes were estimated from soil atmosphere samples taken at different depths, and the CO2 flux on each soil layer was calculated using a gas diffusivity model. The total annual emissions were greater in the pasture, with sharper seasonal variation when compared to the native ecosystems, which were very similar. For all ecosystems, fluxes were closely correlated with soil temperature, and with cumulative precipitation in different timescales. In all three ecosystems (for several occasions), we found a significant CO2 production in the deeper layers of the soil, especially in the depth of 75-100 cm.