There is a useful on-line 6-page paper on the wild service tree (Sorbus torminalis) and its conservation here:
Demesure-Musch, B. & Oddou-Muratorio, S. (2004) EUFORGEN Technical Guidelines for genetic conservation and use for wild service tree (Sorbus
torminalis). International Plant Genetic Resources Institute, Rome, Italy. http://openpdf.com/viewer?url=http://www.euforgen.org/fileadmin/bioversity/publications/pdfs/1039.pdf
The illustrated text covers a general description of the tree, its economic importance, its global distribution (with an excellent map) and, of course, material in regard to its conservation.