IANA botanist, but I think this method doesn't work on some trees (i.e. millennia-old olive trees) because old tissue is not there anymore, or because they have messed up rings, or on trees that have multiple trunks.
So IIUC they integrate carbon dating, ratio between total size and growth rate and other things.
So IIUC they integrate carbon dating, ratio between total size and growth rate and other things.