From the article
"The millennium-old Bosnian pine was discovered by a group of scientists from Stockholm University, the University of Mainz and the University of Arizona, who announced their findings Friday"
"The team took a core of its wood, which measured one meter in diameter, and counted the annual rings, determining it is the oldest known living tree in Europe"
Claims of "oldest" tree other than the 5000 year-old bristlecone pine in California are not individual "oldest" trees. The tree in Norway, for instance, is a clone of parent tree--which means the age being cited is of the original individual tree that spawned it, as well as its age. Clones (ground layers of branches, root suckers ect.) are part of the original tree, but may not have been living when the older tree was begun, so they are actually younger, just made of the same genetic material.