Seasonal and spatial variability in soil CO2 efflux rates for a central Siberian Pinus sylvestris forest

Abstract

Rates of CO2 efflux from the floor of a central Siberian Scots pine (Pinus sylvestris) forest were measured using a dynamic closed chamber system and by a eddy covariance system placed 2.5 m above the forest floor. Measurements were undertaken for a full growing season: from early May to early October 1999. Spatial variability as determined by the chamber measurements showed the rate of CO2 efflux to depend on location, with rates from relatively open areas (“glades”) only being about 50% those observed below or around trees. This was despite generally higher temperatures in the glade during the day. A strong relationship between CO2 efflux rate and root density was observed in early spring, suggesting that lower rates in open areas may have been attributable to fewer roots there. Continuous measurements with the eddy covariance system provided good temporal coverage. This method, however, provided estimates of ground CO2 efflux rate rates that were about 50% lower than chamber measurements that were undertaken in areas considered to be representative of the forest as a whole. An examination of the seasonal pattern of soil CO2 efflux rates suggests that much of the variability in CO2 efflux rate could be accounted for by variations in soil temperature. Nevertheless, there were also some indications that the soil water deficits served to reduce soil CO2 efflux rates during mid‐summer. Overall the sensitivity of CO2 efflux rate to temperature seems to be greater for this boreal ecosystem than has been the case for most other studies.

Response of soil respiration to temperature and soil moisture: Effects of different vegetation types on a small scale in the eastern Loess Plateau of China

“…Combined correlations of soil respiration between soil temperature and moisture. R s was best predicted by combined models including both T s and W s variables (Davidson et al 1998;Shibistova et al 2002;Epron et al 2004;Jia et al 2006;Chen et al 2013). Epron et al (2004) reported that when W s as a linear variable was added to the temperature variable model, the R 2 of the fitted equations increased from 0.56 to 0.72.…”

Characteristics of soil respiration in upper and lower slope positions with different aboveground biomass: a case study in a Japanese cypress forest

“…The multiple linear regression results showed that fine root biomass accounted for the additional spatial variation in R soil that was not explained by SWC and T soil , because AIC and R 2 of the best-fit model including fine rot biomass as an explanatory factor was better for other models without fine root biomass. Fine root biomass often determines the heterogeneity in R soil Katayama et al, 2009;Shibistova et al, 2002 , and fine root biomass often differs with slope position Enoki et al, 1996;Tateno et al, 2004 . Thus, fine root biomass played an important role in understanding the heterogeneity in R soil on a slope.…”

“…Therefore, it is important to examine the spatial variation in R soil and gather knowledge on how to upscale R soil at a stand scale. R soil is strongly affected by environmental factors, such as soil water content SWC, m 3 m -3 and soil temperature T soil , C, Davidson et al, 1998;Stoyan et al, 2000 . It is also well known that R soil is influenced by biological factors such as fine root biomass Hanson et al, 1993;Shibistova et al, 2002, litter amount Fang et al, 1998 , and microbial biomass Scott-Denton et al, 2003 . These factors, which are potential determinants of R soil , often differ with topography such as slope position e.g., McCarthy and Brown, 2006;Tamai, 2010 , slope aspects e.g., Hanson et al, 1993 , and slope degree e.g., Creed et al, 2013 .…”

“…For example, it has been shown that the nitrogen availability decreases upslope, and the aboveground biomass decreases and fine root biomass increases upslope, owing to a shift in carbon allocation from aboveground to belowground sources Enoki et al, 1996;Tateno et al, 2004 . High fine root biomass often facilitates root respiration and dead root decomposition, resulting in high R soil Katayama et al, 2009;Shibistova et al, 2002 . These studies imply that higher fine root biomass might result in higher R soil in the upper slopes, where the aboveground biomass is typically low.…”

Seasonal spatial pattern of soil respiration in a temperate urban forest in Beijing

“…In turn, these characteristics might contribute in various ways (e.g. fine root distribution, microbial activity, litter quality and quantity) to the soil respiration of the whole forest (Shibistova et al, 2002;Murphy et al, 2008).…”