Anew forest grew on land that was previously farmland. this would be an example of what kind of succession

This is an example of secondary succession. Secondary succession occurs on severely disturbed ground that previously supported vegetation. Fire, flood, forest clearance, removal of grazing animals, hurricanes and other factors inaugurate secondary succession. In this case a forest was cleared to be occupied as farmland and has since been abandoned. Thus the forest will start to take over. 

They are called independent