Moisture availability constrains soil trace gas fluxes in an eastern Amazonian regrowth forest
Steel
Vasconcelos, School of Forest Resources and Conservation, University of Florida, P.O. Box 110760, Gainesville, FL 32611-0760 USA, svascon@ufl.edu
(Presenting)
Daniel
Zarin, School of Forest Resources and Conservation, University of Florida, zarin@ufl.edu
Eric
Davidson, The Woods Hole Research Center, edavidson@whrc.org
Francoise
Ishida, Instituto de Pesquisa Ambiental da Amazônia, yoko@ipam.org.br
Elisana
Santos, Instituto de Pesquisa Ambiental da Amazônia, elisana@ipam.org.br
Maristela
Machado
Araújo, Departmento de Ciências Florestais, Universidade Federal Rural da Amazônia, maristela@ufra.edu.br
Débora
Veiga
Aragão, Departmento de Ciências Florestais, Universidade Federal Rural da Amazônia, debora@ufra.edu.br
Lívia
Rangel-Vasconcelos, Soil and Water Science Department, University of Florida, livia@uf.edu
Francisco
Assis
Oliveira, Departmento de Ciências do Solo, Universidade Federal Rural da Amazônia, fassis@ufra.edu.br
William
McDowell, Department of Natural Resources, University of New Hampshire, Bill.McDowell@unh.edu
Cláudio José
Reis de Carvalho, Embrapa Amazônia Oriental, carvalho.bel@terra.com.br
Changes in land-use and climate are likely to alter moisture availability in tropical forest soils, and subsequent changes in trace gas fluxes may have an impact on atmospheric chemistry. Quantitative assessment of the role of moisture availability as regulator of soil trace gas fluxes is rather limited. The objective of this study was to quantify the effect of moisture availability on soil trace gas fluxes in an Amazonian regrowth forest. We measured the efflux of carbon dioxide (CO2), nitric oxide (NO), nitrous oxide (N2O), and methane (CH4) from soil in response to increased soil moisture availability as part of an ongoing dry-season irrigation experiment. In the absence of irrigation, soil CO2 efflux decreased during the dry season while irrigation maintained soil CO2 efflux levels similar to the wet season. Large variations in soil CO2 efflux consistent with a significant moisture constraint on respiration were observed in response to soil wet-up and dry-down events. Annual soil C efflux for irrigated plots was 27 and 13 % higher than for control plots in 2001 and 2002, respectively. In general, fluxes of N2O and CH4 were higher during the wet season and both fluxes increased during dry-season irrigation. There were no treatment or seasonal effects on NO fluxes. Overall, the significant soil moisture constraint on soil CO2 efflux suggests that possible alterations in soil moisture availability due to climate and land-use changes could have significant effects on regional CO2 fluxes.