Date of this Version
A study of unusual interest and significance in the application of ecological principles to the solution of an economic problem has recently been completed. It deals with the causes for the absence of western yellow pine in brush vegetation of various types that occur throughout the mountainous portions of northern Utah, eastern Idaho, and western Wyoming, and, in fact, form a much interrupted and fragmented belt whose center extends from the Gulf of California to west-central Montana. Many of these brush sites, especially in northern Utah and southern Idaho, lie immediately below the Douglas fir type (which is continuous) and would normally be expected to support yellow pine, since they have the same elevation as pine clad areas in other parts of the West. An attempt to improve the brush cover by the planting of pines during a 5-year period ended in failure and led to the present investigations. They were conducted with the idea of determining the feasibility of planting pines, and thus extending the natural range of the forest, and of discovering means whereby areas suitable for the growth of pine could be determined.