Abstract: Soil freezing-thawing cycle is common in mid-high latitude and high altitude regions, which may affect soil physicochemical and/or biological properties, and further, soil respiration process. To study the variations of soil respiration rate under  freezing-thawing cycle is of significance in accurately estimating global carbon budget. Taking the sandy grassland (SG), Mongolian pine savanna (MPS), and farmland (FD) in Keerqin Sandy Lands as test objects, a laboratory experiment was conducted to study their soil respiration rates under  freezing-thawing. Land use pattern had significant effects on the soil respiration rate. In the control (no freezing-thawing), the respiration rate was higher in SG than in MPS and FD (P<0.05), with the value being 0.339, 0.258, and 0.234 μmol CO₂·m^-2·s¹ , respectively; while under freezingthawing, the soil respiration rate was significantly higher in SG and MPS than that in FD (P<0.05). The mean soil respiration rate in SG, MPS, and FD under one freezing-thawing cycle was 0.276, 0.243, and 0.233 μmol CO₂·m^-2·s^-1, and that under multi freezing-thawing cycles was 0.314, 0.274, and 0.259 μmol CO₂·m^-2·s^-1respectively. The Q₁₀value in SG, MPS, and FD was 116.0, 26.2, and 16.4, respectively, suggesting the strong effects of land use pattern on the temperature dependence of soil respiration at low temperature in winter.

Key words: Landscape structure, Landscape heterogeneity, Vegetation, Shenyang