Continuous estimation of winter carbon dioxide efflux from the snow surface in a deciduous broadleaf forest

Abstract

[1] The objective of our study was to estimate CO 2 efflux from the snow surface in a deciduous broadleaf forest throughout the duration of winter on the basis of a continuous measurement of CO 2 concentration at the soil-snow interfaces. Continuous CO 2 efflux was estimated from the CO 2 concentration gradient across the snow cover. We examined the accuracy of the values obtained from the CO 2 concentration gradient across the snow cover by comparing them with the values observed by the closed static chambers. Although each couple of the values from both methods had relatively large differences, the amounts of the values were consistent. The average CO 2 efflux ± 1SD was 1.4 ± 1.0 gCO 2 m À2 d À1throughout the duration of winter. The estimated CO 2 efflux in winter is considered to be reasonable, compared with the value obtained by a relationship between soil temperature and soil respiration in the same forest and with the values reported in forest ecosystems in middle latitudes. Our value is, however, smaller than the value obtained by the eddy covariance technique at a tower in the same forest. We attempted to estimate the hypothetical CO 2 efflux, minimizing the impact of pressure pumping. The average CO 2 efflux was estimated at 2.0 gCO 2 m À2 d À1 .

Winter soil CO2 efflux in two contrasting forest ecosystems on the eastern Tibetan Plateau, China

“…Our study showed that soil CO 2 effluxes from frozen soils were relatively stable in two forest ecosystems during winter. This result is consistent with many other studies conducted in forest ecosystems (Suzuki et al 2006;Wang et al 2010).…”

“…Our measured values of mean winter soil CO 2 efflux were higher than all of the values reported for boreal coniferous forest ecosystems or temperate deciduous broad-leaved or hardwood forest ecosystems (Rustad and Fernandez 1998;Kurganova et al 2003;Hubbard et al 2005;Groffman et al 2006;Suzuki et al 2006;Schindlbacher et al 2007;Wang et al 2010). For example, moderate soil CO 2 effluxes of 0.5-0.7 lmol m -2 s -1 were recorded during winter in coniferous forests in Austria, Germany, Russia and USA (Sommerfeld et al 1996;McDowell et al 2000;Kurganova et al 2003;Schindlbacher et al 2007;Muhr et al 2009).…”

“…Recently, a few studies have demonstrated that prominent soil CO 2 fluxes were released from snow-covered or frozen forest soils during the winter period (Hubbard et al 2005;Monson et al 2006;Suzuki et al 2006;Schindlbacher et al 2007;Wang et al 2010). In the present case, mean winter soil CO 2 effluxes were 1.08 ± 0.15 lmol m -2 s -1…”

“…5 Variation of winter CO 2 effluxes in forest ecosystems with latitude. Data shown in the figure were reported in our study (Suzuki et al 2006;Hubbard et al 2005;Wang et al 2010;Groffman et al 2006;Rustad and Fernandez 1998;Schindlbacher et al 2007;McDowell et al 2000;Muhr et al 2009;Kurganova et al 2003) from low to high latitude mean winter soil CO 2 efflux at 31 N were much higher than those estimated for mid and high latitudes. Winter soil CO 2 efflux may be controlled by the soil substrate, root activity and subsurface temperature influenced by thickness and duration of snow cover (Brooks et al 2004;Monson et al 2006).…”

“…This is partly because forest ecosystems at high altitudes or latitudes were once thought dormant during the long winter period (Winston et al 1997). But a growing number of studies have convincingly demonstrated that winter soil respiration is a pronounced component of the annual carbon budget in these ecosystems (Mariko et al 2000;Hubbard et al 2005;Mo et al 2005;Monson et al 2006;Suzuki et al 2006;Schindlbacher et al 2007;Wang et al 2010). Moreover, Brooks et al (2004) concluded that annual carbon sequestration is overestimated substantially when winter CO 2 fluxes are not included.…”