Estimating CO2 flux from snowpacks at three sites in the Rocky Mountains

Abstract

Soil surface CO(2) flux (F(s)) is the dominant respiratory flux in many temperate forest ecosystems. Snowpacks increase this dominance by insulating the soil against the low temperature to which aboveground components are exposed. However, measurement of F(s) in winter may be impeded by snow cover. Likewise, developing annual F(s) models is complicated by seasonal variation in root and microbial metabolism. We compared three methods of measuring sub-snow F(s): (1) dynamic chamber measurements at the upper snowpack surface (F(snow)), (2) dynamic chamber measurements at the soil surface via snowpits (F(soil)), and (3) static estimates based on measured concentrations of carbon dioxide ([CO(2)]) and conductance properties of the snowpack (F(diffusional)). Methods were compared at a mid-elevation forest in northeastern Washington, a mid-elevation forest in northern Idaho, and a high-elevation forest and neighboring meadow in Wyoming. The methods that minimized snowpack disturbance, F(diffusional) and F(snow), yielded similar estimates of F(s). In contrast, F(soil) yielded rates two to three times higher than F(snow) at the forested sites, and seven times higher at the subalpine meadow. The ratio F(soil)/F(snow) increased with increasing snow depth when compared across all sites. Snow removal appears to induce elevated soil flux as a result of lateral CO(2) diffusion into the pit. We chose F(snow) as our preferred method and used it to estimate annual CO(2) fluxes. The snowpack was present for 36% of the year at this site, during which time 132 g C m(-2), or 17% of the annual flux, occurred. We conclude that snowpack CO(2) flux is quantitatively important in annual carbon budgets for these forests and that the static and dynamic methods yield similar and reasonable estimates of the flux, as long as snowpack disturbance is minimized.

Role of atmospheric circulation with respect to the interannual variability in the date of snow cover disappearance over northern latitudes between 1988 and 2003

“…It influences both plant phenology [Galen and Stanton, 1995;Ouerbauer et al, 1998;Van Wijk et al, 2003;Dye and Tucker, 2003;Grippa et al, 2005a] and the carbon cycle via the increased ecosystem respiration after melting [Goulden et al, 1998;Chapin et al, 2000;Frauenfeld et al, 2004]. Moreover, snow also plays a role in maintaining carbon fluxes during the winter through its insulating effect on soil temperatures [McDowell et al, 2000].…”

Ecosystem Respiration in a Seasonally Snow-Covered Subalpine Grassland

“…Preliminary measurements and leak checking with elevated CO 2 showed that this ventilation hole did not permit entry of external air. The difficulty of accessing the site over winter necessitated use of a smaller more portable system, in our case a LI-8100 (Li-Cor Inc., Lincoln, Nebraska, U.S.A.) with a 20-cm-diameter chamber and 'snowshoe' to allow measurement of CO 2 efflux directly from the snow surface (McDowell et al, 2000). The 20-cm-diameter chamber of the LI-8100 chamber has pressure vents to prevent pressure gradients.…”

“…From measurements in ecosystems with colder and longer winters there is substantial evidence that respiration continues beneath snow and this may be a significant contributor to annual C balance (Sommerfeld et al, 1993;Monson et al, 2006aMonson et al, , 2006bLarsen et al, 2007). Measured instantaneous rates of CO 2 efflux for snow-covered ecosystems have been as slow as 0.02 mmol CO 2 m 22 s 21 in an arctic tundra (Jones et al, 1999) to much faster rates of 0.71-0.86 mmol CO 2 m 22 s 21 in a subalpine meadow (Liptzin et al, 2009) and 0.77 mmol CO 2 m 22 s 21 in a temperate conifer forest (McDowell et al, 2000).…”

“…Much of the research on respiration beneath snow has focused on high-latitude and/or high-altitude ecosystems of the northern hemisphere with mean winter air temperatures that are significantly below freezing (McDowell et al, 2000). We currently have no data on ecosystem respiration under snow for temperate subalpine C3 grasslands.…”

Quantificação das emissões de CO2 pelo solo em áreas sob diferentes estádios de restauração no domínio da mata atlântica

“…Emissões em clima temperado são maiores no verão do que no inverno, independentemente do tipo de cobertura vegetal. [15][16][17] A quantificação das emissões de CO 2 também é tema relevante, e a busca por equipamentos de baixo custo e de fácil manuseio em campo tem sido constante. Dentre os métodos empregados, o da câ-mara dinâmica determina o fluxo de CO 2 emitido baseado na variação de concentração dos gases emitidos pelo solo no interior da câmara, 18 com determinação direta das concentrações por analisadores de gás infravermelho, também conhecido como IRGAS, do inglês, Infra Red Gas Analiser.…”