Abstract: To understand the effects of land use type on soil carbon storage and soil respiration, a comparative study was made to study the characteristics of soil carbon storage and soil respiration under three different land use types, i.e., pure willow plantation (WP), willow-poplar mixed plantation (WPP), and pure poplar plantation (PP) on the lowlands along the Huaihe River in Funan of Anhui Province, East China. The organic carbon storage in 0-30 cm soil layer in WP, WPP, and PP was 6.80, 8.50 and 7.71 g·kg^-1, and the corresponding organic carbon density was 2.88, 3.26, and 2.95 kg·m^-2, respectively. Under the same land use types, both the soil organic carbon storage and density decreased with soil depth. The mean annual soil respiration rate in WP, WPP, and PP was 1.61, 2.33 and 1.61 μmol·m^-2·s^-1, respectively, and the mean daily soil respiration rate was the maximum (6.64 μmol·m^-2·s^-1) in summer and the minimum (0.13 μmol·m^-2·s^-1) in winter. There was an exponential relationship between soil respiration rate and ground surface air temperature, with the R² value being 0.71 for WP, 0.62 for WPP, and 0.54 for PP. The WPP was beneficial to the sequestration of soil organic carbon, as compared to WP, and the lower soil organic carbon storage in WP was related to its extensive management. It was suggested that in the future forest management, reasonable tillage and fertilization should be taken to improve soil fertility and enhance soil carbon sequestration.

Key words: heavy metal, Populus euphratica, rhizosphere bacteria, Salix maizhokung garensis, plant growthpromoting bacteria (PGPB).