I've tried lots of different approaches from jerking them out by hand (works for up to about 1/2" dia), long-handled loppers, thinning saw, mowing, all the way to gouging up everything with the tractor. When I disabled my tractor this summer, I also bought a PullerBear so I could continue battling seedlings and saplings on my trails. Pulling one at a time tends to make a lot less mess. Mowing leaves little stubs (which may or may not try to grow back), but can be uncomfortable/hazardous underfoot; same with larger stumps. The Stihl thinning saw also leaves stubs, but works pretty well (ie quickly); I use the tractor or a chainsaw on larger trees. If most of yours are still pretty small, something like a Ratchet Rake or maybe a Piranha might work, too. I've often thought that the ideal gadget would be kind of like the claw on a claw hammer. This would hook the stems to pull them up, then swipe backwards on the ground to release the stems from the claws...I think the Ratchet Rake an Piranha may work somewhat like this, but I've never tried either, myself.