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Moisture availability constrains soil trace gas fluxes in an eastern Amazonian regrowth forest. Steel Vasconcelos, Daniel Zarin, Eric Davidson, Francoise Ishida, Elisana Santos, Maristela Araújo, Débora Aragão, Lívia Rangel-Vasconcelos, Francisco Oliveira, William McDowell, Claudio Carvalho
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Moisture availability constrains soil trace gas fluxes in an eastern Amazonian regrowth forest Steel Vasconcelos, Daniel Zarin, Eric Davidson, Francoise Ishida, Elisana Santos, Maristela Araújo, Débora Aragão, Lívia Rangel-Vasconcelos, Francisco Oliveira, William McDowell, Claudio Carvalho University of Florida Woods Hole Research Center Instituto de Pesquisa Ambiental da Amazônia Universidade Federal Rural da Amazônia University of New Hampshire Embrapa Amazônia Oriental
CO2,N2O, and CH4 greenhouse gases • NO precursor of O3 • Gas production and consumption strongly linked to the availability of soil moisture • Limited understanding of the mechanisms that control variation in soil trace gas emissions • Rainfall, litterfall, and decomposition confounding factors in observational studies • Very few manipulative studies in tropical forests
Quantify the impacts of soilmoisture availability on trace gas fluxes in a regrowth forest stand in eastern Brazilian Amazonia
Pará State, Brazil • Regrowth forest (13 years old in 2000) • Rainfall = 2540 mm • Tair = 24 – 27 oC • Oxisol
Treatments = control, irrigation, and litter removal • Replicates = 4 • Plot size = 20 m x 20 m
Repeated measure analysis: treatment, date, and treatment x date effects • Contrast analysis: season (wet vs. dry) and treatment within season effects
CO2 efflux during the dry season • Irrigation maintained wet season Rsoil levels • Soil CO2 pulse events
Wet season efflux > dry season efflux • Irrigation > control
Wet season efflux > dry season efflux • Irrigation efflux > control efflux
Moisture availability constrains CO2, N2O, and CH4 emissions during the dry season • The substantial impacts of soil moisture on soil CO2 efflux may have important implications for soil respiration modelling approaches
Trenching experiment • Treatments: • control (C) • root exclusion (NR) • litter removal (NL) • litter removal + root exclusion (NLNR) Root respiration = C – NR Microbial respiration litter = C – NL Microbial respiration soil = C – NLNR
Osório Oliveira, Glebson Souza, Evandro Silva (MANFLORA field assistants) • Raimundo da Silva (Estação Experimental de Castanhal – UFRA) • The Andrew W. Mellon Foundation and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil for the grants