@Rinate,
@Briand,
How about converting them to bio-char? I've seen plans for making a simple bio-char processor -- one smaller barrel inside a larger one -- and converting them into something you know will help, as opposed to something that might spread an invasive weed?
Here's Guy McPherson showing how his bio-char processor is built and used (plus a bit about weed wackers and scythes:
http://www.youtube.com/watch?v=qQmg8ybcEdY
And here's a more detailed video with a live firing by Peter Hirst, who's a bio-char guru in the Northeast:
http://www.youtube.com/watch?v=RXMUmby8PpU
Maybe you can get together with a neighbor or two and make a bio-char kiln?