I run the shredder over anything that the tractor can push over if it doesnt uproot. IF it uproots, then I can use the FEL to finish ripping it out and push it into a pile. Small stuff less than 3" sometimes will just bend over and is easily cut by the bush hog when bent like that. At worst case, it just knocks the limbs off, but it will mangle anything that gets under it enought that is isnt going to live any longer. If the shredded remains are thick enough, I then use the tooth bar on the fel to scrape them all into a pile and sometimes pull the larger tree roots out. Boxblade with scarifiers lowered helps with getting out the roots also. By shortening the 3rd arm to the max, it puts the scarifiers deeper into the ground and keeps the blade from gathering dirt. Small stuff like you are talking about, I just shred with the bush hog and keep it mowed as the sprouts try to come back. I have worked out a sweet gum thicket pretty well with just a bush hog and FEL. A few of the larger thorn trees required digging around them at all angles with the BB scarifies to pop the roots before I could push them over with and uproot the main taproot with the FEL. Thorn trees are the hardest to get out. Pines are about the easiest as they have very little root system, plus they dont sprout back out like the sweet gums. Sweet gums and thorn trees will continue to sprout out from the roots for years and will require frequent mowing to keep them down.