Tree Core (IMAGE) Columbia Climate School Caption Scientists assembled a record of rainfall going back over 750 years by measuring widths of annual fokienia hodginsii rings. The rings are visible in cores taken from the tree trunks; these do not damage the tree. Credit Kevin Krajick/Earth Institute, Columbia University. Usage Restrictions proper credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.