I have learned to live with my ailanthus forest.
It is about a third of my lot. I have a few that are almost a foot in diameter. They are all the things that have been said about them.
After 15 years of active battle, I really don't believe you can ever truly get rid of them. So I accepted their existence and found that a heavily coppiced patch (about 10 feet by 30 feet), will produce a huge pile of pretty straight sticks about 1/2 in in diameter and four to six feet long by the end of a season. The sticks I use for fuel in my rocket hot-water loop stable/
chicken coop heater in the winter. I have also used them as woven stick
fence panels, and
chicken crates, but they are not strong
enough to keep goats contained. I think they also would be excellent for those salvaged material beehives that are on Permies in another
thread.
In my observation, they do not seem to contain the same toxicity when dead as they do when alive. Goats will not eat starts, but they do eat the tops that blow out, as well as the big seed clusters. They provide shade, need no maintenance and do the whole carbon-exchange thing, and seem to be a good nursery for other tree starts such as Idaho
native red mulberry and
black locust, catalpa and walnut at my place. The only tree that I have planted that can choke ailanthus out Siberian Elm (Another, curse) and Hybrid Poplars (used for making toilet paper in the PNW).
I doubt I will ever go down the road of making fiber from them, but once you have them, you need to resolve that they will always be around. Even if only at the edges.
Oh yeah,
ants seem to like them too.