Temporal variation of soil CO2 efflux in oil palm-based agroforestry systems in eastern Amazon

The soil carbon dioxide (CO₂) efflux dynamics and its controlling factors of Amazonian agroforestry systems are poorly understood. The objective of this study was to evaluate the temporal variation of soil CO₂ efflux in oil palm-based agroforestry systems and the relation between efflux and biotic (microbial and total soil carbon, microbial respiration, fine roots, individual components of agroforestry systems (AFS)) and abiotic factors (soil moisture and temperature). The measurements were taken during the less rainy (December 2010) and rainy (May 2011) periods. The soil CO₂ efflux was highest during the rainy season, probably due to increased microbial activity influenced by climatic factors coupled with biotic factors. The soil CO₂ efflux correlated positively with soil moisture and microbial biomass carbon and negatively with soil temperature and metabolic quotient, but these correlations were weak. The soil CO₂ efflux was sensitive to the type of agroforestry system and to rainfall seasonality.

Key-words:
Global warming; soil microbial biomass; soil moisture; soil respiration; soil temperature