Abies sachalinensis (トドマツ) and Picea glehnii (アカエゾマツ) are major components of the sub-boreal forest of Hokkaido. The objective of this study was to investigate young individuals of these species, from the ecophysiological perspective, to establish relations between their known life-history strategies and their physiological characteristics.

The study took place on a sub-boreal forest plot at the Uryu Experimental Forest of Hokkaido University (N 44º 19’, E 142º 15'). Ten shade-growing individuals of each species were divided into two height classes: seedlings, if height < 50cm; and saplings, if height > 100cm. The canopy openness over each individual was assessed by analyzing hemispherical photography and by measuring average light incidence with a light sensor. Leaf nitrogen content was measured from dry leaf samples and leaf pigments were analyzed from frozen leaf samples by High Performance Liquid Chromatography. Also, photosynthetic light response curves and chlorophyll fluorescence were measured during summer. The study took place from May to August 2009.