a less gloomy outlook than the preceeding posts. first of all, how wide is the gap in the bark? if it's narrow, theres a chance that the bark could grow back across the gap. u could facilitate this by trimming away any loose chunks that would interfere with a relatively quick regrowth. does the gap run all the way around? if even a third of the circumference is unharmed the tree could survive. the tree will die from girdling but this is not instantaneous. it will take at least one year. that gives some hope of regrowth.
how much do u care about the tree? if u could thin the top the tree would stand a better chance of survival. girdling deprives the roots of the sugars that form in the leaves. to help the root system much, i'd expect u'd need to remove 25% of the top or more.
finally, as rambler indicated, there is such a thing as a bridge-graft. it involves running severalmall branches as grafts across the gap. any sap that gets down to the roots will prolong their life, and a proper bridge-graft accomplishes this. i can't tell u how to do it but many good gardening books explain it. perhaps the logging company would be willing to pay for a tree surgeon to do this.
it's not so much that the roots starve in this case but they run out of stored sugars which is what allows the tree to leaf out next year.
don't know if this helps any. good luck with it!