A study was carried out from 1973 to 1976 to determine snow-trapping efficiency and ablation rates in circular openings of 1/4–6 tree heights (H) in diameter, spaced 10 H between centers. The greatest snow accumulation was in 2-H and 3-H openings, closely followed by 1-H and 3/4-H openings. Below 3/4 H, accumulation dropped off rapidly, with the minimum being in the uncut forest. Ablation rates (expressed as centimetres water equivalent per day) were least in the 1 H, followed closely by 3/4 H. Rates increased above and below 3/4 H and 1 H, with maximum rates in 5-H and 6-H openings.In 1977 and 1978 measurements were made in 14 closely spaced (2 H between centers) 1-H openings. Snow accumulation and ablation rate were the same as in the more widely spaced 1-H openings.