Seasonal variations in stem CO2 efflux in the Neotropical rainforest of French Guiana
Résumé
Stem CO2 efflux (Es) is a significant component of total ecosystem respiration, but there is only scant information on seasonal variations in Es in tropical rainforests and on the main factors explaining these variations.• MethodsWe conducted a comprehensive 18-month study in French Guiana to try to better understand which environmental factors contribute to seasonal variations in Es in two habitats differing in soil water conditions.• ResultsIn both habitats, large seasonal variations in Es were observed for most trees. The main variations occurred during climatic transition periods and were consistent with seasonal variations in soil and total ecosystem respiration.• DiscussionSeasonal variations in atmospheric conditions, including air temperature, did not explain seasonal variations in Es. In contrast, seasonal variations in surface soil water content clearly induced seasonal variations in Es in each habitat. Both soil drought and flooded conditions induced a decrease in Es.• ConclusionOur results emphasize the need to integrate the influence of soil water content on Es into global models that simulate the response of forest ecosystem fluxes to climate changes.