Each year a tree’s growth ring has two parts; one is wide and light colored, and the other is narrow and dark. This grows during the wet spring and early summer when the tree has a lot of sap, and the cambium cells giving rise to the trunk growth are large and thin walled.As the summer winds down and the transition to the cooler autumn occurs, the tree’s growth rate slows.Welcome and thank you for visiting the Science of Tree Rings web pages, designed to be the ULTIMATE source for information on the science of Dendrochronology.I've designed these pages to be easily understood by people at all levels of education, from elementary school students to high school students, from first grade teachers to college professors.This page does not attempt to cover the details of wood formation that make tree rings possible, but rather provides an overview of common wood characteristics and anomalies that you will need to identify when you are crossdating.Variation in these rings is due to variation in environmental conditions when they were formed.Many people think that the Science of Tree Rings web site is supported completely by my university. I do all the web page information searching, coding, and designing at home in my home office in my free time, which likely amounts so far to thousands of hours of personal time. In fact, if you buy anything after linking to Amazon through my stores, I still receive a small percentage.I paid for the Microsoft Expression Web Pro and Dreamweaver CS5 software, my Macbook Pro laptop (also running Windows 7 via VMware), my Dropbox Pro account, high-speed Internet and home wireless, wireless printer, and all the "hidden" overhead (paper, cartridges, electricity), even the extra server space needed for the many files! I'd like to keep these tree-ring web pages online for another 20 years! First, click on the "A to Z Index" button to the upper left for a comprehensive list of items available from these pages.
Dendrochronologists demand the assignment of a single calendar year to a single ring.
Much can be learned about a species of tree and its environment by discovering its age, and researchers employ several methods to date trees.
The most common, most accurate way to find the age of a tree is to count the number of rings visible when their trunk is cut horizontally.
This results in the cambium cells becoming smaller and thicker-walled.
By winter, when the sap finally stops flowing, a smooth dark ring marks the end of the tree’s annual growth.