The content of main chemical components (total nitrogen and carbon, soluble and polymeric sugars, organic acids, and mineral substances) were studied in the leaves of 73 boreal plant species with different types of Grime-Ramenskii strategies. The type of ecological strategy was demonstrated to be related to the chemical composition of the leaf, with the substances studied falling into two groups. The concentrations of the substances belonging to the first group (nitrogen, organic acids, and mineral substances) were minimum in stress-tolerant and maximum in ruderal species. With respect to the type of strategy, these concentrations increased in the following series: S --> C --> R. Conversely, the concentrations of the substances of the second group (carbon and soluble sugars) decreased in this series. The nitrogen concentration and the carbon-to-nitrogen concentration ratio in leaves may be used for identifying the types of strategies.