Here is a great article from Val Williamson at Decoded Science about dendrochonology. Despite the, apparently unintentional, pun at the end of the first paragraph, some good points are made:
Anthropologists are, among other things, detectives – piecing together evidence to work out how people behave and survive in certain conditions. Archaeology is anthropology of the past, so a proven timeline for dating archaeological artefacts is a great investigative tool. Dendrochronology supplies physical evidence for a timeline compiled through international data-sharing between practitioners. This fascinating branch of science provides anthropologists with accurate dates, and other information, and has roots going back millennia.
I heard a talk at the SAAs in St. Louis regarding the dating of really old trees that I hadn’t thought about. If you date burned sections of a tree, like from a hearth or fire ring, and you know the trees in that area can be really old, then you have to know where in the tree’s cross-section you are taking your sample from. The difference between the inside of the tree (older) and the outside of the tree (newer) could be a thousand years or more. That’s a pretty big set of error bars when you are trying to date a site that may have only been occupied for a few days or weeks.