Paul, I found this abstract of an article on a web site:


Douglas-fir Christmas trees shipped in railroad box cars from the
Pacific Northwest to Los Angeles, Calif., suffer varying degrees of
deterioration, depending on treatment before shipment, length of time
in cars, and temperatures within loads during shipment. Test shipments
were made in 1962 in a standard box car and a mechanically refrigerated
car, with recording thermometers at three levels within the loads.

Additional shipments in standard box cars were made in 1964 using crushed
ice blown in on the loads as a coolant. At Los Angeles the 1962 trees were
mounted under simulated home conditions and their useful life measured for
11 days. Needle-drop proved a poor measure of deterioration but observations
of color, dryness, and needle-drop on the 10th day showed obvious differences.

Time of cutting, previous fertilizing, along with position in packing, and
shipping temperature affected the useful life and value of trees.


Tim O'Connor