Component respiration, ecosystem respiration and net primary production of a mature black spruce forest in northern Quebec

Abstract

We measured respiratory fluxes of carbon dioxide by aboveground tree components and soil respiration with chambers in 2005 and scaled up these measurements over space and time to estimate annual ecosystem respiration (R(e)) at a mature black spruce (Picea mariana (Mill.) B.S.P.) ecosystem in Quebec, Canada. We estimated periodic annual net primary production (NPP) for this ecosystem also. R(e) was estimated at 10.32 Mg C ha(-)(1) year(-)(1); heterotrophic respiration (R(h)) accounted for 52% of R(e) and autotrophic respiration (R(a)) accounted for the remainder. We estimated NPP at 3.02 Mg C ha(-1) year(-1), including production of bryophyte biomass but not including shrub NPP. We used these estimates of carbon fluxes to calculate a carbon use efficiency [CUE = NPP/(NPP + R(a))] of 0.38. This estimate of CUE is similar to those reported for other boreal forest ecosystems and it is lower than the value frequently used in global studies. Based on the estimate of R(h) being greater than the estimate of NPP, the ecosystem was determined to emit approximately 2.38 Mg C ha(-1) year(-1) to the atmosphere in 2005. Estimates of gross primary production (GPP = NPP + R(a)) and R(e) differed substantially from estimates of these fluxes derived from eddy covariance measurements during 2005 at this site. The ecological estimates of GPP and R(e) were substantially greater than those estimated for eddy covariance measurements. Applying a correction for lack of energy balance closure to eddy covariance estimates reduces differences with ecological estimates. We reviewed possible sources of systematic error in ecological estimates and discuss other possible explanations for these discrepancies.

Responses of carbon dioxide flux and plant biomass to water table drawdown in a treed peatland in northern Alberta: a climate change perspective

“…The contribution of R r to R ff has been quantified using closed chamber technique in various forest ecosystems. Hermle et al (2010) separated black spruce root respiration from soil total respiration by measuring the difference between control and trenched plots. They found that the R r was 24 % of the soil total respiration.…”

“…The remaining four hummocks and four hollows were left intact to quantify the difference in CO 2 emission between cut (having minimal tree roots) and intact (with all tree roots) plots. During July to September 2012, all plots were clipped every two weeks to ensure that soil surface was free of live mosses, shrubs and herbs following Hanson et al (2000), and Hermle et al (2010). The trenched and intact plots were clipped so that we could isolate soil respiration (measured at trenched plots) from R r + soil respiration (measured at intact plots).…”

“…Hanson Hermle et al, 2010;Wang et al, 2008;Díaz Pinés et al, 2010;Kuzyakov, 2006;Brant et al, 2006). In all cases the assumption has been made that the trenched roots die off within a short time and that afterwards the measured R ff can solely be attributed to heterotrophic soil respiration.…”

Effects of bryophyte and lichen cover on permafrost soil temperature at large scale

“…The thermal conductivity of the cover increases by around 1 order of magnitude from dry to water-saturated bryophytes and lichens, while the heat capacity even increases by around 2 orders of magnitude (O'Donnell et al, 2009;Soudzilovskaia et al, 2013). Moreover, thermal conductivity increases strongly during the transition from liquid to frozen water inside the bryophyte and lichen cover, while heat capacity is reduced (Hinzman et al, 1991). Therefore, a large and important seasonality of the insulating effect is expected: in winter and, to a lesser extent, in autumn and spring, the insulating effect of bryophytes and lichens will be small due to the high thermal conductivity of ice and water.…”

Satellite-Based Inversion and Field Validation of Autotrophic and Heterotrophic Respiration in an Alpine Meadow on the Tibetan Plateau

“…Re is mainly composed of two components, autotrophic respiration by plants (Ra) and heterotrophic respiration by heterotrophic microorganisms (Rm) [75]. Ra is the sum of respiration from all plant components, including leaves, stems, flowers of aboveground biomass and roots of underground biomass, which generally depend on current photosynthate [43], and thus couple closely with GPP [42].…”