Tracing the references, you wind up at http://www.itreetools.org/ http://www.itreetools.org/ which describes the approach the Forestry service took to model out

Tracing the references, you wind up at http://www.itreetools.org/ http://www.itreetools.org/ which describes the approach the Forestry service took to model out the value of a tree, with some detail at http://www.itreetools.org/resources/archives.php http://www.itreetools.org/resources/archives.php