© 2007 Heron Publishing—Victoria, Canada
Plasticity of shoot and needle morphology and photosynthesis of two Picea species with different site preferences in northern Japan
Hiroaki Ishii (1, 2), Satoshi Kitaoka (3, 4), Taiji Fujisaki (1), Yutaka Maruyama (4, 5) and Takayoshi Koike (3, 6)
1. Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan / 2. Corresponding author (hishii@alumni.washington.edu) / 3. Field Science Center for Northern Biosphere Studies, Hokkaido University, Sapporo 060-0809, Japan / 4. Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo 062-8516, Japan / 5. Present address: Research Planning and Coordination Division, Forestry and Forest Products Research Institute, Tsukuba 305-8687,
Japan / 6. Present address: Silviculture and Forest Ecology Studies, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589,
Japan / Received May 29, 2006; accepted April 20, 2007; published online August 1, 2007
Summary
We compared shoot and needle morphology and photosynthesis in Picea glehnii (Friedr. Schmidt) M.T. Mast. and Picea jezoensis (Sieb. et Zucc.) Carr. trees planted on immature volcanic ash and well-developed brown forest soils to investigate whether
species differences in morphological and physiological plasticity affected tree growth on different soil types. Height growth
of P. glehnii was reduced by about 10% on volcanic ash compared with forest soil, whereas that of P. jezoensis was reduced by more than 60%. Needle morphology of P. glehnii was unaffected by soil type. In contrast, needles of P. jezoensis trees growing on volcanic ash were shorter, narrower and thicker, with less dry mass and area, than those of trees growing
on forest soil, and specific needle area was lower, indicating lower foliar light-interception efficiency. In both species,
changes in needle morphology with increasing irradiance were similar in trees growing on both soil types, indicating that
plasticity of needle morphology was unaffected by soil type. In both species, shoot mass and shoot silhouette area were lower
and needle mass per unit shoot mass was higher in trees growing on volcanic ash than in trees growing on forest soil. Trees
of both species had more needles per unit shoot length, lower shoot silhouette to projected needle area ratios and lower shoot
silhouette areas per unit shoot mass (SAM) on volcanic ash than on forest soil, indicating lower shoot-level light-interception
efficiency. For P. glehnii, the response of shoot morphology to increasing irradiance was similar on both soil types, with the exception of SAM, which
showed lower plasticity in trees growing on volcanic ash. In contrast, shoot-level morphological plasticity of P. jezoensis was reduced in trees growing on volcanic ash. Light-saturated maximum photosynthetic rate (Pmax) of P. glehnii was unaffected by soil type, whereas mass-based Pmax of P. jezoensis was lower in trees growing on volcanic ash than in trees growing on forest soil. In P. jezoensis trees growing on forest soil, area-based Pmax increased with increasing irradiance, but this response was not observed in trees growing on volcanic ash. As a result, area-based
Pmax at the top of the canopy was 39 to 54% lower in trees growing on volcanic ash than in trees growing on forest soil. Our results
indicate that constraints on morphological acclimation to high irradiances may contribute to reduced height growth of P. jezoensis on volcanic ash.
Keywords:
morphological plasticity, photosynthetic acclimation, Picea glehnii, Picea jezoensis, shoot architecture.
