Temporal and spatial variability of soil surface and profile respiration were measured in the first growing season of a newly established hybrid poplar (Populus deltoides x P. petrowskyana var. Walker) plantation established by Alberta-Pacific Industries Ltd. at Ashmont, Alberta, Canada. Soil surface CO₂ efflux was measured using a LICOR 6400-09 soil respiration system from a total of 55 collars placed along transects north, east, south, and west of an eddy covariance tower established at the site. Profile CO₂ concentrations at 0.02, 0.10, 0.25, and 0.50 m were measured continuously using Vaisala GMM 221 solid-state infrared CO₂ sensors. For the period July 27 – November 6, 2005, C lost via soil surface respiration was 0.62 Mg C ha^-1 (102 days). Soil C efflux decreased from 1.33 g C m^-2 day^-1 in July to 0.20 g C m^-2 day^-1 in November ranging from 0.47 – 4.95 g C m^-2 day^‑1 (July) and from 0.04 to 0.52 g C m-2 day^‑1 (November). Soil CO₂ concentrations along the soil profile were closely related to soil temperature and moisture, and responded positively to rain events. Soil CO₂ concentration close to the surface was about 4 times higher than ambient CO₂, increasing to 10 times ambient at 0.5 m depth. Temporal and spatial variability of soil respiration may be attributed primarily to the influence of biophysical factors on organic material decay derived from previous land-use (hay production).