Soil CO₂ efflux rates in different tropical vegetation types in French Guiana

Abstract

-Soil CO 2 efflux rates were measured from July to September 1994 in three vegetation types (primary forest, hardwood plantation and clear-cut) near Sinnamary, French Guiana (5° 15' N, 52°55' W), using a portable closed-chamber infrared gas analysis system. Mean soil CO 2 efflux rates were: 2.3 μmol m -2 s -1 in the primary forest versus 2.5 μmol m -2 s -1 in the clear-cut and 2.9 μmol m -2 s -1 in the plantation. Diurnal patterns of soil CO 2 efflux in the primary forest and hardwood plantation did not show significant (P ≤ 0.05) changes. No correlation between soil CO 2 efflux rate and soil temperature was detected in these two vegetation types. In the clearcut, a very pronounced peak in soil CO 2 efflux rate occurred, which was strongly correlated with soil temperature. In all three sites, the range of average soil CO 2 efflux rates among collars (spatial differences) largely exceeded the range observed among daily means (temporal variation

Soil CO2 efflux in a beech forest: dependence on soil temperature and soil water content

“…Since soil CO 2 efflux depends on species composition, site location (both climatic and edaphic conditions), stand ages and sylvicultural practices [1,4,6,8,14,18] (3.6 ± 0.4 and 3.3 ± 0.3 μmol m -2 s -1 , respectively). The lack of significant diurnal changes in soil CO 2 efflux under a closed canopy has already been reported [9]. Therefore, we assumed that our diurnal means were reli- 1 and 311 g C m -2 year -1 ).…”

Climatic Influences on Seasonal and Spatial Differences in Soil CO2 Efflux

“…If the measurement depth is too close to the surface, the opposite will be observed. As a result of this time lag, hysteresis will occur when plotting the complete diurnal or annual cycle of soil CO 2 efflux versus soil temperature: morning (or spring) fluxes will differ from the evening (or fall) fluxes at the same temperature (Janssens et al 1998). Inappropriate measurement depths will therefore artificially increase the variability in the relationship between the measurements of soil CO 2 efflux and temperature.…”

Soil Respiration in Beech and Spruce Forests in Europe: Trends, Controlling Factors, Annual Budgets and Implications for the Ecosystem Carbon Balance

“…Furthermore, soil respiration frequently shows a very pronounced microsite variability, probably linked to the heterogeneity of soil conditions within a system (Dugas 1993;Jensen et al 1996;Janssens et al 1998).…”