Native Americans Were Able to Prevent the Encroachment of Trees

question 87

Multiple Choice

Native Americans were able to prevent the encroachment of trees and maintain the tallgrass prairies by

• A) establishing an extensive irrigation system to increase soil moisture, thus favoring grasses.
• B) plowing much of the land for agriculture.
• C) restricting the migrations of bison, which caused the bison to browse heavily on tree seedlings and thus kill them.
• D) setting fires periodically to kill the trees.
• E) clear- cutting the forests for timber and fuel.