Seasonal variations in stem CO2 efflux in the Neotropical rainforest of French Guiana

Stahl , Burban , Goret , Bonal

• Introduction Stem CO2 efflux (E s) is a significant component of total ecosystem respiration, but there is only scant information on seasonal variations in E s in tropical rainforests and on the main factors explaining these variations. • Methods We conducted a comprehensive 18-month study in French Guiana to try to better understand which environmental factors contribute to seasonal variations in E s in two habitats differing in soil water conditions. • Results In both habitats, large seasonal variations in E s 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. • Discussion Seasonal variations in atmospheric conditions, including air temperature, did not explain seasonal variations in E s. In contrast, seasonal variations in surface soil water content clearly induced seasonal variations in E s in each habitat. Both soil drought and flooded conditions induced a decrease in E s. • Conclusion Our results emphasize the need to integrate the influence of soil water content on E s into global models that simulate the response of forest ecosystem fluxes to climate changes.

Mots clés: SOIL WATER CONTENT; TERRA FIRME FOREST; SEASONALLY FLOODED FOREST

Mots clés: TROPICAL RAINFOREST; STEM CO2 EFFLUX

Domaines: Sylviculture, foresterie

Stahl, Burban, Goret, Bonal. Seasonal variations in stem CO2 efflux in the Neotropical rainforest of French Guiana. Annals of Forest Science, 2011, 68 (4), pp.771-782. ⟨10.1007/s13595-011-0074-2⟩. ⟨hal-00930807⟩