iBT TOEFL Topic Vocabulary Breakthrough Unit 056

iBT TOEFL Topic Vocabulary Breakthrough Unit 056
Author: Li Xiaolai

56. Three major forest areas exist in the United States. The western forests of the Rocky Mountains and the Pacific coast are coniferous and contain Douglas fir, ponderosa pine, western white pine, Engelmann spruce, and white fir. More than half of the softwood lumber yield of the United States comes from the productive Douglas fir forests of the Pacific Northwest. The South Atlantic and Gulf states account for most of the remaining softwood lumber, chiefly from longleaf, shortleaf, loblolly, and slash pines. Hardwoods, yielding about one-fourth of the total production, are found in the eastern half of the United States, with particularly dense stands in the area surrounding the Mississippi and Ohio river valleys. Among the many hardwood species are oaks, black walnut, yellow poplar, and sugar maple.

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