Authors: R Oguchi K Hikosaka T Hiura T Hirose
Publish Date: 2006/07/11
Volume: 149, Issue: 4, Pages: 571-
Abstract
The photosynthetic light acclimation of fully expanded leaves of tree seedlings in response to gap formation was studied with respect to anatomical and photosynthetic characteristics in a natural cooltemperate deciduous forest Eight woody species of different functional groups were used two species each from midsuccessional canopy species Kalopanax pictus and Magnolia obovata from latesuccessional canopy species Quercus crispula and Acer mono from subcanopy species Acer japonicum and Fraxinus lanuginosa and from vine species Schizophragma hydrangeoides and Hydrangea petiolaris The lightsaturated rate of photosynthesis P max increased significantly after gap formation in six species other than vine species Shade leaves of K pictus M obovata and Q crispula had vacant spaces along cell walls in mesophyll cells where chloroplasts were absent The vacant space was filled after the gap formation by increased chloroplast volume which in turn increased P max In two Acer species an increase in the area of mesophyll cells facing the intercellular space enabled the leaves to increase P max after maturation The two vine species did not significantly change their anatomical traits Although the response and the mechanism of acclimation to light improvement varied from species to species the increase in the area of chloroplast surface facing the intercellular space per unit leaf area accounted for most of the increase in P max demonstrating the importance of leaf anatomy in increasing P maxWe thank the staff at Tomakomai Experimental Forest for their technical support and the experimental setup T Koike T Kohyama and S Tsuyuzaki for the generous offer of instruments and S Kitaoka T Aikawa S Kosuge S Takahashi O Muller E Nabeshima and Y Miyazaki for support for the experiments advice and discussion This work was financially supported in part by GrantsinAid of the Japan Ministry of Education Culture Sports Science and Technology and by a JSPS Research Fellowship for Young Scientists
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