Photosynthetic acclimation of deciduous broad-leaved tree species was studied along a vertical gradient within the canopy of a multi-species deciduous forest in northern Japan. We investigated variations in (1) local light regime and CO₂ concentration ([CO₂]), and (2) morphological (area, thickness and area per mass), biochemical (nitrogen and chlorophyll concentrations) and physiological (light-saturated photosynthetic rate) attributes of leaves of seven major species on three occasions (June, August and October). We studied early successional species, alder (Alnus hirsuta (Spach) Rupr.) and birch (Betula platyphylla var. japonica(Miq.) Hara); gap phase species, walnut (Juglans ailanthifoliaCarrière) and ash (Fraxinus mandshurica var. japonica Rupr.); mid-successional species, basswood (Tilia japonica (Miq.) Simonk.) and elm (Ulmus davidiana var. japonica (Rehd.) Nakai); and the late-successional species, maple (Acer monoBunge). All but maple initiated leaf unfolding from the lower part of the crown. The [CO₂] within the vertical profile ranged from 320–350 ppm in the upper canopy to 405–560 ppm near the ground. The lowest and highest ambient [CO₂] occured during the day and during the night, respectively. This trend was observed consistently during the summer, but not when trees were leafless. Chlorophyll concentration was positively related to maximum photosynthetic rate within, but not among, species. Leaf senescence started from the inner part of the crown in alder and birch, but started either in the outer or top portion of the canopy of ash, basswood and maple. Chlorophyll (Chl) to nitrogen ratio in leaves increased with decreasing photon flux density. However, Chl b concentration in all species remained stable until the beginning of leaf senescence. Maximum photosynthetic rates observed in sun leaves of early successional species, gap phase or mid-successional species, and late successional species were 12.5–14.8 μmol m⁻² s⁻¹, 4.1–7.8 μmol m⁻² s⁻¹ and 3.1 μmol m⁻² s⁻¹, respectively.

Resistance of plants to ozone stress can be classified as either avoidance or tolerance. Avoidance of ozone stress may be explained by decreased stomatal conductance during ozone exposure because stomata are the principal interface for entry of ozone into plants. In this study, a coupled photosynthesis–stomatal model was modified to test whether the presence of ozone can induce avoidance of ozone stress by stomatal closure. The response of Siebold's beech (Fagus crenata), a representative deciduous tree species, to ozone was studied in a free-air ozone exposure experiment in Japan. Photosynthesis and stomatal conductance were measured under ambient and elevated ozone. An optimization model of stomata involving water, CO₂ and ozone flux was tested using the leaf gas exchange data. The data suggest that there are two phases in the avoidance of ozone stress via stomatal closure for Siebold's beech: (1) in early summer ozone influx is efficiently limited by a reduction in stomatal conductance, without any clear effect on photosynthetic capacity; and (2) in late summer and autumn the efficiency of ozone stress avoidance was decreased because the decrease in stomatal conductance was small and accompanied by an ozone-induced decline of photosynthetic capacity. Ozone-induced stomatal closure in Siebold's beech during early summer reduces ozone influx and allows the maximum photosynthetic capacity to be reached, but is not sufficient in older leaves to protect the photosynthetic system.

We investigated the adaptation of three spruce species (Picea glehniiMasters, P. jezoensis Carr. and P. abies Karst.) to growth in northern Japan on serpentine soils (characterized by high concentrations of heavy metals and Mg, a low Ca/Mg ratio and low fertility) and fertile brown forest soils. Among species, seedling survival on serpentine soil was highest in P. glehnii. Shoot growth of P. glehnii was similar whether grown on serpentine or brown forest soil, whereas shoot growth of the other species was significantly less on serpentine soil than on brown forest soil. On serpentine soil, needle life span of P. glehnii was at least 3 years longer than that of the other two species. Needle area per shoot of P. glehnii was significantly higher on serpentine soil than on brown forest soil up to a shoot age of 8 years. In all three species, light-saturated photosynthetic rate (P_max) decreased with needle age independently of soil type. However, on serpentine soil, P_max in P. glehnii was higher, particularly in older needles, than in the other species. Furthermore, on serpentine soil, needle concentrations of nitrogen and phosphorus were higher in P. glehnii than in the other species. We conclude that P. glehnii is better adapted to serpentine soil than P. jezoensis and P. abies at least in part because of its greater needle life span and higher needle nutrient concentrations.