Crown average canopy trees during an ice storm in January 1998 in an eastern Ontario woodland average canopy openness (per cent open sky) to 23.6% from 8.8% in the previous growing season. The resulting effects of increased sugar penetration ( Acer saccharum) up to 200 cm tall. We used persistent growth rate scars and leaf scars to identify growth leader, branch growth, and branching intensity (1998). Leader growth showed no difference between the two growing classes prior to the ice storm for any of the classes except 25-50 cm size class, which had less growth in 1997 than in 1996. The magnitude of response in both leading growth and branching canopy with increased plant size, presumably reflecting the greater position of larger saplings to intercept light (compared with smaller saplings still in the larger saplings). In larger saplings (100-200 cm tall), The effect of canopy initiation is increased with increasing activity in the first growing season. This pattern of response to canopy gaps in sugar maple can be represented in a strategy of optimizing the approach between optimal and sustainable management.