A NATIONAL PLAN" FOR AMERICAN FORESTRY 



1521 



The watershed-protective value of forests in all ownerships is 

 summarized in table 8. 



TABLE 8. Watershed-protective value of forests in the United States by ownership 



MAJOR CRITICAL SITUATIONS 



A single watershed problem may be common to parts of several 

 drainages. For example, watershed conditions in the piedmont and 

 upper coastal plain sections from the Potomac River around the At- 

 lantic seaboard to Texas form a single problem, and so do those in the 

 semiarid woodlands throughout the West. In order to avoid repeti- 

 tion, statements as to major critical watershed situations will be based 

 on representative groups of conditions rather than on the drainage 

 divisions previously used. No attempt will be made here to cover 

 the entire country or to present statistics in such a way as to make 

 possible a summation into national totals. 



MISSISSIPPI BLUFF LANDS AND SILT LOAM UPLANDS 



The bluff lands of the Mississippi River and the lower reaches of 

 its main tributaries form a narrow belt extending from New Orleans 

 to St. Paul, through the lower Mississippi, Ohio, Missouri, and upper 

 Mississippi River drainages. They are the steep, broken slopes and 

 adjacent silt loam uplands that flank the river terraces. They total 

 about 20 million acres, of which two thirds lies below the mouth of 

 the Missouri River, and are characterized by windblown and silt 

 loam soils. 



These bluff lands are believed to contribute more to the silt problem 

 of the Mississippi River than any other area of the same size. The 

 greatest watershed problem here is erosion, although flood control is 

 almost equally important. The high erosibility of the soils naturally 

 favors the formation of deep gullies, which spread with exceptional 

 rapidity and are most difficult to check. This is particularly true in 

 the Yazoo River uplands, in the southern tip of Illinois, and in the 

 bluff lands of southwestern Wisconsin and of adjoining areas in 

 Minnesota, Iowa, and Illinois. In some counties of the Yazoo up- 

 lands as much as 40 percent of the area is badly gullied, the gullies 

 reaching in many cases to a depth of 20 or 40 feet and in some cases 

 to more than 100 feet. 



