SEASONAL-CHANGES IN SHOOT AND ROOT PRODUCTION AND IN CARBOHYDRATE CONTENT OF SALMONBERRY (RUBUS-SPECTABILIS) RHIZOME SEGMENTS FROM THE CENTRAL OREGON COAST RANGES

An extensive rhizome system is an important aspect of the morphology a nd architecture of salmonberry (Rubus spectabilis Pursh) and of its po tential for regrowth following disturbance. Seasonal activity of the r hizome system was studied by collecting rhizome segments monthly from February through October 1988 and February 1989 from four sites. Total nonstructural carbohydrate content was determined and segments were i ncubated in a growth chamber to determine periodicity of shoot and roo t production. The number and dry weight of shoots peaked in February a nd March, declined from April through June when aboveground shoot grow th was greatest and were generally low through the dry summer months. Root production was highest from August through October and generally lower the rest of the year. Total nonstructural carbohydrate content w as highest during the dormant season and dropped to the lowest level i n midsummer. Shoot production was more closely associated with total n onstructural carbohydrate content than was root production. The signif icant reduction in shoot production potential suggests a time in the a nnual growth cycle when the species capacity for regrowth following di sturbance is at a relatively low level.