Contribution of root respiration to spatial-temporal variation of soil respiration in a Haloxylon ammodendrons ecosystem in Gurbantunggut Basin

On the basis of the sparse distribution of Haloylon ammodendrons, we designed experiment to study the spatial-temporal variation of soil respiration in a Haloxylon ammodendrons ecosystem in Gurbantunggut Basin. A 401 cm transect between two Haloxylon ammodendrons was built on 11 April, 2005. We started to measure soil respiration along the built transect in May, 2005. The experiment completed in September, 2007. The result of experiment showed that soil respiration under Haloxylon ammodendron crown decreased with distance from stem to the edge of crown. In the open area, shrub roots have no influence on soil respiration. Considering the results of the experiment, the contribution of root and rhizosphere respiration (Rr) to total soil respiration was determined. We deduced that Haloxylon ammodendrons root respiration averaged as 0.0768gCO2 m− 2 h− 1, account for 51.3% of total soil respiration. The seasonal pattern of soil CO2 efflux under trees, in open areas and estimated root respiration was simulated by temperature-respiration models, moisture-respiration models and bivariable models driven by soil temperature (Ts) and moisture (Ms), respectively. We inferred that bivariable models driven by soil temperature and moisture describe the seasonal variation of soil respiration better than other two kinds of models. The components of soil respiration, Rd and Rr, respond differently to environmental change. Rr is more sensitive to the dynamic of temperature. And combined model of soil temperature and moisture on respiration explain the seasonal variation of Rd. better than that of Rr.