The petrified logs in this image are located in the Chemnitz Museum of Natural History. Researchers have been studying a number of petrified logs that have been dug up over the years in this town in Germany, some of which have been found whole and in a vertical orientation as if the trees were buried while still standing. Studies on several of the logs have lead researchers to believe that the logs are part of a petrified tropical forest that is encased in the sediment and ash layer of an ancient volcano.
One of the tree species tentatively identified at the site is "Arthropitys ezonata Goeppert", a tropical tree species that is long extinct. In fact, all of the logs found at Chemnitz are of tree species that are now extinct.
I first heard about this story from Gus at Eucalytologics who sent me a link to an article in Spiegel Online.