Scaling up of the physiology^based response of cool-temperate forest ecosystems to disturbance and environmental change.

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This project aimed to describe the overall mechanism at forest ecosystem scale response to global change. Setting mixed cool-temperate deciduous broad-leaved forests as main target ecosystem, we scaled up from organ-based physiological processes to a whole individual growth and community dynamics used quantitative theoretical models based on field observation.Experiments were carried out at various scales ; e.g. open-top CO_2 enrichment systems on experimental field to fertilization/logging experiment on forest ecosystem. At every scale physiological response to treatment or disturbance was species specific. We described the differential response cascade explaining species difference. Physiology-based model of foliage photosynthesis was extended to include nitrogen-limitation.Shoot-module-based analysis of three-dimensional tree formation processes was carried out using Magnolia obovata and the genus Abies as model trees. We extracted branching role of M.obovata. Short-shoot type lateral branches were commonly formed, of which significance, clarified through simulation experiments, was not to reduce mutual shading but to reduce assimilate use due to the overall shortage of photosynthetic production. Population-level development of Abies stands was simulated using PipeTree, a shoot-based, physiological simulator. The simulation suggested that single shoot characteristics need to be changed with height, through water potential change, so that observed phenomena of even-aged population development.