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As a managed ecosystem, soil respiration in farmland shelterbelt has seldom been reported. In this study, soil respiration was measured using an automated CO2 efflux system (LI-COR 8100) in 2005 and 2006. Additionally, the effects of abiotic factors on the variation in soil respiration during growing season and the site variation were examined at the Populus and Ulmus pumila farmland shelterbelts in Xinjiang, China. Soil respiration followed the soil temperature in growing season and variation between sampling years at two sites. Soil temperature at 50 cm depth (T-50) explained 78.5% of the variation in soil respiration during growing seasons with an exponential equation in Populus site, while soil temperature at 35 cm depth (T-35) explaining 64.4% in U. pumila site. There was no apparent relationship between soil respiration and soil water content. The soil respiration was significantly higher in Populus than in U. pumila site, mean soil respiration rate was 3.71 and 1.82 mu mol CO2 m(-2) s(-1), respectively. The greater growth status, the greater quantum yield of photosystemll (Phi PSII) and apparent photosynthetic electron transport rate (ETR) were consistent with the higher soil respiration rate in Populus site. Temperature was a dominant factor driving the temporal variability of soil respiration in growing seasons. (C) 2011 Elsevier Masson SAS. All rights reserved.