[Temporal and spatial variations of soil respiration in an Artemisia ordosica shrubland ecosystem in Kubuqi Desert].

Based on the dynamic measurements of soil respiration using a closed dynamic chamber and its related environmental factors in a desert shrubland ecosystem regularly during the growing season (May-September) of 2006, we studied the diurnal and seasonal variations of soil respiration of two different land cover soils and their responses to soil temperature, soil water content and biotic factors. The objective was to evaluate the temporal and spatial patterns of soil respiration and their responsible factors in Artemisia ordosica shrubland in Kubuqi Desert, Inner Mongolia, China. The diurnal variation of soil respiration showed an asymmetric single-peak pattern, with the peak value occurring around 12:00. Soil respiration fluctuated greatly during the growing season, reaching peak values in July-August. There was a significant linear relationship between soil respiration rate and soil water content at 10 cm depth. Most of the seasonal variation in soil respiration (75%-77%) could be explained by the variation in soil water content. The mean soil respiration under the shrub canopy was (155.58 +/- 15.20) mg x (m2 x h)(-1), which was significantly higher than that for the bare ground between the shrubs (110.50 +/- 6.77) mg x (m2 x h)(-1). The sensitivity of soil respiration to soil water content was also significantly higher for the soils under the canopy than for the bare ground soils. The spatial variation of soil respiration was caused mainly by the root biomass, which can be explained about 43% of heterogeneity. The results suggest that variation on a small time and space scales must be taken into consideration when estimating soil CO2 efflux in the desert ecosystems.