Prehistoric human impact on the environment in the upland North American Southwest

Some early Anasazi (prehistoric Puebloan) agricultural practices tended to be land-extensive and made substantial impact on the forests, primarily through clearing by burning. Later agriculture tended to be more land-intensive, but longer duration occupations by larger populations also had significant local effects on the forests, through both clearing for fields and through intensive harvest of firewood. Strategies of early Anasazi agriculture that resulted in forest depletion probably also tended to maximize the power output of the economic systems, and therefore must have had considerable selective value. Depletion of various wild resources was an important impetus to culture change, leading, in conjunction with population growth, to more intensive farming practices, and contributing to the tendency to aggregate in large villages at various times in the prehistoric period.