© 2003 Heron Publishing—Victoria, Canada
Acclimation of shoot and needle morphology and photosynthesis of two Picea species to differences in soil nutrient availability
Hiroaki Ishii (1, 2, 3), Machiko Ooishi (4), Yutaka Maruyama (5) and Takayoshi Koike (4)
1. Biosphere Dynamics Research Group, Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan / 2. Division of Forest Resources, Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan / 3. Author to whom correspondence should be addressed (hishii@alumni.washington.edu) / 4. Field Science Center for Northern Biosphere Studies, Hokkaido University, Sapporo 060-0809, Japan / 5. Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo 062-8516, Japan / Received April 27, 2002; accepted October 26, 2002; published online April 1, 2003
Summary
To investigate morphological acclimation to differences in nutrient availability, we compared shoot and needle morphology
of Picea glehnii (Friedr. Schmidt) M. T. Mast. and Picea jezoensis (Siebold & Zucc.) Carrière trees growing on nutrient-poor volcanic ash and nutrient-rich, brown forest soil. Trees of both
species were shorter and had more open canopies when growing on volcanic ash than when growing on brown forest soil. Nutrient-poor
conditions limited height growth less in P. glehnii than in P. jezoensis. In both species, trees growing on volcanic ash had shorter annual increments in the previous year and more needles per shoot
length and, hence, a smaller shoot silhouette area (SSA) relative to needle dry mass (NDM) than trees growing on brown forest
soil. Soil type had less effect on shoot projected needle area (PNA). Total needle area (TNA) of P. glehnii shoots was similar between soil types, whereas TNA of P. jezoensis was lower in trees growing on volcanic ash than in trees growing on brown forest soil. For both species, low SSA in response
to nutrient-poor conditions resulted in low shoot SSA/PNA ratios, indicating high within-shoot self-shading. Shoot SSA/TNA
of P. glehnii was lower in trees growing on volcanic ash than in trees growing on brown forest soil, indicating that needles were sun-acclimated.
In contrast, shoot SSA/TNA of P. jezoensis was higher in trees growing on volcanic ash than in trees growing on brown forest soil. The contrasting response of TNA to
low nutrient availability was associated with species-specific differences in needle morphology. Needles of P. glehnii growing on volcanic ash were slightly shorter, wider, thicker and heavier than those of trees growing on brown forest soil,
indicating morphological acclimation to high irradiance. Needles of P. jezoensis growing on volcanic ash were shorter than those of trees growing on brown forest soil, but did not show morphological acclimation
to high irradiance in width, thickness or mass. For both species, nutrient-poor conditions decreased maximum photosynthetic
rate (Amax) per NDM. However, when expressed per PNA, the decrease in Amax was reduced, and when expressed per SSA, Amax was higher in trees growing on volcanic ash than in trees growing on brown forest soil. On volcanic ash, Amax per NDM was lower for P. glehnii than for P. jezoensis. However, morphological changes at the shoot and needle levels reversed this trend when Amax was expressed per SSA or per PNA. The species-specific differences in morphological response to differences in soil nutrient
availability suggest that P. glehnii is more tolerant of nutrient-poor conditions, whereas P. jezoensis is better at exploiting nutrient-rich soils.
Keywords:
morphological acclimation, needle area, nutrient availability, Picea glehnii, Picea jezoensis, shoot silhouette area.
