An alternative to cutting them down, if you don't have the equipment to move the trees after you cut them. Go to the farm supply and tell them you want a quart or so of herbacide, 2 4 D or something similar. Take a hatchet or machete and hack around the tree cutting down thru the cabium layer, then spray the herbacide in the hack. It will kill the tree and gradually the limbs will rot off opening up the canopy.