On trees apples, pears, walnuts, chestnuts usually grow, but now books do the same, too!
In Berlin, in the Prenzlaure Berg district, you can find the 'Book Forest', an original literary exchange project related to BookCrossing. It is a real tree of books with many shelves and tiny windows protected by little plastic curtain in which more than one hundred volumes of different genres (from novels to history books, from entertainment literature to children's stories in German and not only) lie, waiting to be consulted.
The idea, promoted by BauFachFrau and the Federal Ministry of Education and Research, is to create a free outdoor library in a public space. The key words are exchange and sharing; everyone can take a book provided that they put another in the appropriate shelves. The messages are many and all positive: educating people to read, spreading volumes and, why not, allowing more control on deforestation because circulating books already printed, limits the production of paper.
In addition, it is appropriate to specify to the nature lover that the trees are dead (without any other function) and they obtain a new life.