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Explore how soil CO2 efflux and its components change after moving sand dunes are stabilized with shrubs, and how abiotic factors affect those components at different scales.

Soil CO2 efflux from a sand-stabilized area was compared to that from moving sand dunes in the Tengger Desert. To partition rhizosphere respiration (R-R) from soil basal respiration (R-B), a root-isolation plot was established.

Compared to moving sand dunes, total soil respiration (R-T) in the sand-stabilized area increased 3.2 fold to 0.28 +/- 0.08 mu mol CO2 m(-2) s(-1), two thirds of which was from R-B. Shrub patchiness produced spatial variation in soil respiration, whereas temporal dynamics of soil respiration were affected mainly by soil water content. Shallow soil water content (0-20 cm) influenced R-T and R-B, whereas deep soil water content (30-210 cm) influenced R-R and the ratio R-R/R-T. During most of the year when soil water content was below field capacity, diurnal changes in soil respiration were partially decoupled from soil temperature but could be modeled using soil temperature and photosynthetic active radiation.

Sand-dune stabilization increased soil respiration, and increased R-B from biological soil crust and altered soil properties such as increased soil organic matter contributed more than increased R-R from increased shrubs.