Elberling 2007

Elberling B. 2007. Annual soil CO2 effluxes in the High Arctic: the role of snow thickness and vegetation type. Soil Biology and Biochemistry 39: 646-654.

This author studied the total annual efflux of CO2 at three vegetation communities in Endalen valley on Svalbard. The three communities are each dominated by one characteristic species of plant, and are named accordingly: Dryas, Cassiope, and Salix, and from the description of the sites and their environmental parameters, there appears to be high agreement between these communities and those found at Alexandra Fjord, Ellesmere Island.

The depth and duration of snow cover was a major factor controlling (directly and indirectly) soil conditions and thus respiration. Snow depth varied with vegetation type, though the causal relationship is probably snow to plants, via soil temperature (more snow = higher winter temperatures) and soil moisture content (snow accumulates at and melts into depressions and certain slope positions). Higher temperatures and wetter conditions correlated with higher soil respiration, both in winter and summer. All sites experienced a brief period of water saturation in the upper 5cm of the soil during spring thaw, though sites varied in when thaw happened, with Dryas first and Salix last, corresponding with winter snow cover depth.

Soil conditions among the sites seem to have been broadly similar; not surprising considering the close proximity of sites and the consistent soil type across the valley, though soil under Cassiope tetragonal patches was more acidic. This acidity seems related to a reduced concentration of base cations (especially Ca2+ and K+) under Cassiope plants.

Summer water content did not correlate with annual CO2 flux, which this author attributes to the generally well-drained soils, a lack of large precipitation events, and long periods without rain leading to typically dry soils everywhere, though soil respiration at the Dryas site may have been water-limited, as this was the driest site.

Winter temperatures in the soil averaged warmer than -10ºC at all sites, warm enough for microbial activity. A burst of CO2 during spring thaw was not predicted from soil parameters, but was attributed to increasing microbial activity associated with warming temperatures and the release of high-quality organic material from winter-killed microbial cells. Winter CO2 efflux averages were 0.11 to 0.28 µmol / m^2 / s, not far from values we found (for example) at the Cassiope site at Alexandra Fjord.

This paper contains much that is valuable to my current research, including both the data and patterns found and the discussion with other relevant references.