| 研究実績の概要 |
Clear and divergent temporal patterns were observed for 13C, 18H and 2H of cellulose extracted from 796 tree rings (80-year series) cut from wood cores collected on 14 trees the Kiryu experimental watershed.
13C was very sensitive to change in canopy structure while 18O was less, highlighting an increase in tree photosynthesis after stand harvest in 1960, likely due to reduced competition. The trend in 13C after 1980 likely results from the increase atmospheric CO2 concentration. Difference in 13C between old and young trees are likely due to higher light absorption by the crown of old trees rather than hydraulic constrains.
Leaf water enrichment in 18O can be predicted satisfactorily but predicting wood cellulose 18O is challenging.
Despite the huge amount of data are still under analysis, the results demonstrates that tree ring isotopes integrate physiological response to changes in the environment (atmospheric CO2, climate, resource availability) and forest structure.
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