Have u.s. landowners contributed to  native american land lost from illegal government seizure of native land?:
First off the ancient rite of war that every nation has lived by including the Lakota, which removed the Nation that was here before them, the victor of war gets the land.  While there was some chicanery and our forefathers  only really won a hand full of battle the Indian Wars were more a war of attrition and the Nations lost the land due to that fact.

Yes, we have contributed to the land, there are more trees than were on the Continent at the time of Columbus's landing.  We grow most of the food uses to survive.