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Forest carbon storage in the upper Great Lakes displays considerable interannual variability, which is largely climate dependant. Annual net ecosystem production (NEP) at the University of Michigan Biological Station (UMBS) in northern lower Michigan varied over 100 % from 1999-2003 (Gough et al., 2007 b). Meteorological and ecological measurements of NEP show that forest growth lags behind canopy photosynthesis, indicating that late season C uptake is stored over winter and applied to spring growth. The objective of this study was to quantify the relationship between late season carbohydrate storage and growth the following year. We tracked seasonal changes of non-structural carbohydrates (starch and soluble sugars) in leaves, twigs, stems, and coarse roots of the dominant canopy species bigtooth aspen (Populus grandidentata Michx.) and northern red oak (Quercus rubra L.) in 2005 and 2006. Seasonal variation of storage carbohydrates in both species was related to canopy photosynthesis, reproductive events, and leaf phenology. In 2005, we observed an inverse correlation between spring twig starch and soluble sugar concentrations in Q. rubra