LDS Conference Center roof, Salt Lake City, UT …a semi-forested roof that was completed nearly TEN YEARS AGO (2000) with bristlecone pines and other native plantings. This was completed even before ASLA’s green roof.

Zimmer Gunsul Frasca Partnership, Architects

http://www.hydrotechusa.com/lds_5.html

http://en.wikipedia.org/wiki/File:Conference_center_roof.jpg

As engineered systems, all trees must have a building platform to support both the botonical physiology and the structural engineering. This means cubic feet of root zone for the sub-soil root mass to form and support the above ground tissues. There is no static state for these trees!

As in many other urban sites, if the objective is to have trees and replace them every 10-15 years, then the pre-planting investments are less important, but, “50′ pines” on top of a tall building, face weather events and micro-climate affects, never produced in a “northern woodlands”. This could be a nightmare where “moving firewood down the elevator” is the least of the manangement’s concens.