Effects of Stem Fraction on the Optimization of Biomass Allocation and Maximum Photosynthetic Capacity

• Published in: Functional ecology 2003-10, Vol.17 (5), p.627-636
• Main Authors: Osone, Y., Tateno, M.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Biomass; Biomass production; Fractions; Fundamental and applied biological sciences. Psychology; Herbs; Human ecology; leaf nitrogen concentration; leaf : root ratio; Leaves; light‐saturated photosynthetic rate; Nitrogen; Plant ecology; Plant roots; Plants; Plants and fungi; stem cost
• ISSN: 0269-8463; 1365-2435
• DOI: 10.1046/j.1365-2435.2003.00763.x

1. A model was developed to examine effects of the stem biomass fraction on the optimal responses of plants to soil nitrogen availability. 2. Our model predicts that the optimal leaf: root ratio and optimal photosynthetic capacity (Pmax) increase with soil N availability. For a given N availability, the optimal leaf: root ratio decreases and the optimal Pmaxincreases with increasing stem fraction. As a result, the increase in optimal leaf: root ratio is smaller, and that in optimal Pmaxis greater, in response to increasing N availability when stem fraction is large. 3. To test these predictions we grew two herbs with different stem fractions: Polygonum cuspidatum Sieb. et Zucc. and Chenopodium album L. Showing excellent agreement with the simulation results, the leaf N concentration and leaf: root ratio of the two herbs increased with increasing N availability, and leaf N concentration was larger for C. album with higher stem fraction than P. cuspidatum. 4. The general tendency for plants with larger stem fractions also to have greater leaf N concentrations and Pmaxwas demonstrated for a wide range of temperate herbs. This suggests that stem fraction may be a source of variation in Pmaxamong plants in the same functional group.