FORESTRY AND FOREST MANAGEMENT 353 



white ash, maples, cotton wood, walnut,, and white, black, and 

 red oaks. The forests, however, are not continuous, and all 

 are mixed. As most of these forests were on land that is 

 valuable for farming, large parts of them have already dis- 

 appeared, and in many localities they are now represented 

 only by woodlots in the pasture lands. 



The forests of the Rocky Mountains are characterized by 

 the presence of the western yellow pine with the Douglas fir 

 and some spruce, and, in the southern half, the pifion pine. 

 The most heavily wooded region of the United States is found 

 in the Pacific Coast forests, where are found also the largest 

 trees in the world. The principal timbers are Douglas fir, 

 western yellow pine, redwood, red cedar, hemlock, and Sitka 

 spruce. 



366. The Forests of Alaska, Porto Rico, and Hawaii. 

 The Alaskan forests are quite extensive and are made up 

 mostly of fir, spruce, and hemlock. Those of Porto Rico con- 

 tain many valuable cabinet woods, as do also the more exten- 

 sive forests of the Philippines where some of the most valu- 

 able woods are found. Little attention has yet been paid to 

 these forests because of the many difficulties connected with 

 lumbering operations. The importation of live stock into 

 Hawaii completely destroyed the tropical forests because 

 grazing exposed the roots and the trees soon died. As a re- 

 sult, the heavy floods soon carried lava, ashes, and debris 

 into the sugar plantations of the lowlands, and the problem 

 became so serious that a careful study was made of the situa- 

 tion. Cattle were restricted to definite areas, and trees 

 which would grow very rapidly were planted on all slopes to 

 protect the lands from further floods. Gradually these trees 

 have been replaced by commercial timber, and the forests 

 will soon be yielding an income. 



367. Forest Regions of Canada. Extending from the 

 Atlantic Coast to the slopes of the Rocky Mountains are vast 

 forests similar to those of the northern United States. They 



