SEASONAL-CHANGES IN CARBOHYDRATE STORAGE AND REGROWTH IN RHIZOMES ANDSTEMS OF 4 BOREAL FOREST SHRUBS - APPLICATIONS IN PICEA-GLAUCA UNDERSTOREY REGENERATION

Understorey scarification methods are used to enhance regeneration of Picea glauca; however, understorey shrubs have been identified as majo r competitors for regenerating tree species. To investigate the respro uting potential of rhizomes of four boreal forest shrub species in the understorey, rhizome segments (30, 15, and 10 cm in length) of Corylu s cornuta, Cornus stolonifera, Rosa acicularis, and Viburnum edule wer e planted in five boreal mixed-wood sites in northern Alberta at four times during the 1994 growing season. Sugar and starch concentrations in rhizome and stem pieces of these shrubs and Epilobium angustifolium were determined for each date. The segments and their regrowth were e xcavated in the autumn of 1995. Rhizome length had no effect on regrow th but there was a marked increase in regrowth for segments planted la te in the growing season. The cryptophyte, E. angustifolium, accumulat ed large amounts of carbohydrates during the growing season, i.e. 28% of dry weight compared with 6-14% of dry weight for the phanerophytic shrubs. All four shrubs had lowest regrowth when total non-structural carbohydrate concentrations were at their lowest levels.