This is a high reliability and accuracy method. The Bluetooth tag is extremely small and can be affixed to an object and used to track and manage inventory, assets, wood, etc...
The problem with Bluetooth tag is that they require energy, so a Battery is required.
NFC are interesting cause many Smartphone can read NFC chip, but, unfortunately, they are currently mostly limited for payment processing.
And as well, they need to be seen on the tree.