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Thursday, 6 October 2016
Trees modify the dynamics of soil CO2 efflux in coffee agroforestry systems1
Published Date 15 August 2016, Vol.224:30–39,doi:10.1016/j.agrformet.2016.05.001
Gomes Lucas de Carvalho a,,,
Cardoso Irene Maria a
Mendonça Eduardo de Sá b
Fernandes Raphael Bragança Alves a
Lopes Vanessa Schiavon a
Oliveira Teógenes Sena a
aDepartment of Soil Science, Federal University of Viçosa, Viçosa, 36570-000 Minas Gerais, Brazil
bDepartment of Plant Production, Federal University of Espirito Santo, Alegre, 29500-000 Espírito Santo, Brazil
Received 7 August 2015. Revised 18 March 2016. Accepted 4 May 2016. Available online 8 May 2016.
. Soil CO2 efflux dynamics were analysed in agroforestry and full-sun coffee systems.
Trees reduced soil temperature and maintained soil moisture in agroforestry systems.
Trees stabilize microclimate conditions and then decrease soil CO2 efflux variability.
Soil temperature is the main driver of soil CO2 efflux in full-sun systems.
Agroforestry systems may help significantly reduce atmospheric carbon levels in forthcoming years through photosynthesis and regulation of soil CO2efflux. This study aimed to characterise the soil CO2efflux dynamics of coffee plants cultivated under agroforestry and full-sun production systems and identify the factors that regulate this process. The study was carried out in agroforestry and full-sun coffee systems on three family farms in Minas Gerais, the Atlantic Forest Biome, Brazil during three consective days on each farm. Twenty 1-m2sampling areas (10 for each system), each separated by a distance of 5 × 5 m and located between coffee plant rows, were selected on each farm. Soil physical and chemical attributes, air temperature and humidity, soil temperature and moisture, the percentage of canopy cover, and soil CO2efflux were measured at each sampling area in the two systems. The air and soil temperature in the agroforestry systems were lower and soil moisture was higher than in the full-sun systems. Soil CO2efflux showed different dynamics in the two systems. Daytime soil CO2efflux was more stable (i.e. from morning to midday) in the agroforestry system (average 15% increase) compared to the full-sun system (average 49.1% increase). Soil CO2efflux was regulated by labile carbon and total nitrogen variation in the agroforestry systems, and by soil temperature variation at a depth of 10 cm in the full-sun systems. A principal components analysis with data from all grouped systems showed that soil CO2efflux was generally positively correlated with soil temperature at 5 and 10 cm depths, and negatively correlated with soil moisture. In conclusion, agroforestry systems promote microclimate stability and decrease soil CO2efflux variability compared to full-sun systems.