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Promoting Regeneration of Aspen in the Boreal and Montane Forests of Alberta
Victor Lieffers and Simon Landhausser, Centre for Enhanced Forest Management, Edmonton, Alberta
Aspen is the most widely distributed tree in Alberta, ranging from the edge of the Great Plains to the boreal forest and up the Rocky Mountains. At the fringe of the Great Plains its growth is limited by drought. In the boreal and lower foothills zone, it is a very productive species and is often a strong competitor with conifers. Its spread into higher zones of the Rocky Mountains is limited by cold soils and short growing season. This presentation describes several findings of recent aspen research at the Centre for Enhanced Forest Management: 1) Root carbohydrates may be high late in the growing season but by early spring (prior to leaf flush) most of these carbohydrates are depleted. 2) Season of logging has little impact on the suckering of aspen if soil disturbance is minimized during logging. 3) Mechanical site preparation and moderate wounding of roots promotes numbers of root suckers. 4) Barriers to emergence of suckers from the soil (i.e., sods of grass, litter from grass or logging slash) delay emergence of and success of suckering. 5) Root damage associated with traffic stimulates number of suckers but most of these are too small to produce vigorous suckers, particularly if barriers limit their emergence. 6) Aspen is spreading into higher elevation sites of Alberta via reproduction from seed. Sites that have been given site preparation after logging lodgepole pine stands are recruiting up to 1000 seedlings/ha.