I remember many times in our field plots at UMBC where we discussed the idea of planting RFID (Radio frequency identification) tags on our trees to improve future re-census and as a way to get around people stealing the tags (Ecosynth Blog: Working Where People Are, December 2012). I recently came across a 2014 review paper by a group of researchers on the TreeCity project out of the University of Pisa in Italy on the same concept, suggesting that RFID tags in trees, combined with towers, base stations, personnel on the ground, and even drones can be used for getting updated information on tree status in an area.
The article was published August 2014 in Urban Forestry and Urban Greening and a pdf of the article can be found at the author's project website after a quick Google search. Imagine RFIDs implanted in trees on our forest plots at UMBC that would enable rapid resurvey of demography by just a person walking around on the ground with a phone, combined with Ecosynth ground based scanning for generating a forest map at the same time!
Image and article credit:
Luvisi, A., & Lorenzini, G. (2014). RFID-plants in the smart city: Applications and outlook for urban green management. Urban Forestry & Urban Greening, 13, 630-637.