I did this on a farm that had not been farmed for several decades, just bushhogged and no-tilled corn for three years, maybe not as thick with trees as yours, and "spikes" were not a problem. Continued no-till for about ten years then plowed it, man did the weeds come on strong after that.


Or you could try one of these from Fecon, I delivered the steel for the expansion project on home page, and know several employees, those things are all that is used around here for site clearing

http://www.fecon.com/start/default.asp