A NATIONAL 'PLAN FOR AMERICAN FORESTRY 363 



mainly with such hardwoods as mixed oaks and hickory. On alluvial 

 bottom lands ash, sweet and black gum, magnolia, sycamore, and other 

 moisture-loving species are included. Upland stands are seldom cut 

 clear and an abundance of smaller trees and reproduction is custom- 

 arily left. Cut-over areas within the range of the pines restock at a 

 very rapid rate as a rule. Large areas of the pine-hardwood lands 

 cleared for agriculture have been abandoned because of erosion, but 

 observations indicate that many old fields are taken over within 5 

 or 10 years by shortleaf and loblolly pine reproduction which tends 

 to check gullying and to heal lesser forms of erosion. 



More than half of the commercial forest area is unprotected from 

 fire and an average of 865,944 acres of this area, largely in long leaf 

 pine, was burned over annually during the years 1926 to 1930 inclu- 

 sive. These ground fires, usually set by livestock owners during the 

 winter season, destroy the forest litter and are so frequent as to pre- 

 vent the accumulation of duff and other surface debris, thereby les- 

 sening the protective efficiency of the forest cover. 



In the Edwards Plateau and " cross- timber" regions of west 

 central Texas the predominant cover consists of scrub oaks, juniper, 

 elm, hackberry, and other species, except along the water courses, 

 where elm, cottonwood, sycamore, and other water-demanding 

 species tend toward luxuriant growth. Toward the west, the scrub 

 species give way to mesquite and shrubs which merge into the grass- 

 land of the prairies and high plains of western Texas. 



The scrub forests of the plateau region are seldom cut extensively, 

 although they are an important source of firewood, fence posts, and 

 other products for local use. The heaviest inroads have been made in 

 the cedar stands. The scrub oak and juniper stands as a rule do not 

 form a continuous forest but often occur as scattering woodland inter- 

 spersed by areas of grassland which, particularly those in the western 

 portion of the plateau, furnish range for large herds of livestock. 

 Heavy and unregulated grazing, the rather thin soils of the region, 

 and the lack of adequate rainfall all combine to keep ground cover in a 

 rather depleted condition. Bray 34 describes the transition from former 

 prairie to scrub-oak woodland that has occurred in this region as the 

 result of overgrazing and a decrease in the number of fires. ^ He also 

 cites the spread of mesquite and shrubs over cattle country in central 

 Texas. 



According to Bray, fires have become relatively infrequent through- 

 out the Edwards Plateau since settlement of the country, but during 

 dry seasons they occasionally do considerable damage to juniper 

 stands. 



RELATION TO WATERSHED PROBLEM 



Experimental studies carried out in northern Mississippi by the 

 Forest Service point to the influence of similar forest cover on the 

 west Gulf drainages in preventing surface run-off and regulating 

 stream flow. Data obtained in 1932 in the upland watersheds of the 

 Yazoo River during a flood period show that less than 0.5 percent of 

 27 inches of ram falling on an undisturbed oak forest ran off the surface 

 while 62 percent ran off a cultivated field. Other data obtained in 

 May 1930 by the United States Bureau of Chemistry and Soils in the 

 fringe forests of Oklahoma show that surface run-off from burned 



3< Bray, W. L. The Timber of the Edwards Plateau of Texas. U.S. Dept. Agr. Forestry Bui. 49, 1904, 



