John, Jamie, Jim, and Rox,
Thanks for those replies.
With the correct device for grubbing and grabbing, I *do* think it will be easy and very much more productive to clear the manzanita with a tractor.
Regarding the appearance of manzanita, it is a miniature tree. The leaves are ever-green, though it is not a conifer type evergreen. It is related to the madrone tree, which also grows on my property. In some ways it is just a dwarf, bonzai madrone, if you will. The 20-30 year old ones I need to remove are 5-9 feet tall. The branches bearing the leaves are in the upper third of the tree. Generally their appearance is "leggy" rather than "bushy". Hope that helps.