Iowa environmentalists are urging people to preserve the past by planting native trees for the future. Iowa Department of Natural Resources bureau chief John Walkowiak says budding foresters all over the state are helping restore the landscape. Walkowiak says trees help hold in soil, preventing erosion and keeping waterways clean. He says they also help provide cleaner air. A D-N-R study finds there are now about two-point-one million acres of forestland in Iowa. That number was almost seven million before the land was settled, starting around 1850. Walkowiak says certain types of trees are considered “native” to Iowa and grow best in specific areas of the state.In the uplands, oak, hickory and walnut trees thrive. In the bottomlands or flood plain areas, green ash or silver maples do best. Walkowiak says Iowans can start a “living legacy” for future generations by planting native trees and other plants.He recommends people consult the state Forest Nursery in Ames for information on buying and planting native trees at 800 865-2477.