They may not have had the same system of land owenership as the Europeans, but they still owned land. Why do you think there were wars between tribes. They fought for resources and you can't separate land/water from resources. To say one can't own land is a philosophical arguement, but when you get into the nuts and bolts stuggle for survival protecting one's land becomes priority number one. (resources trumps any philosophical discussion).
As for land management they would burn acres and acres of land for agricultural needs as well as other effects; some even believe they started the medieval warm period. http://www.sciencedaily.com/releases...0321134617.htm
http://homepages.baylor.edu/gary_stinchcomb/2011/03/