. Insect and disease conditions in the United States, 1979-83 : what else is growing in our forests?. Forest insects United States; Trees Diseases and pests United States; Plants Disease and pest resistance. Mountain Pine Beetle Resources Affected Timber. All unmanaged stands of mature and overmature lodgepole pine, of second-growth mature and overmature ponderosa pine, of mature and overmature western white and sugar pines, and of overmature whitebark and limber pines are susceptible to at- tack. Dead trees must be salvaged for wood or fiber 3 to 5 years after they die; otherwise, they are of
. Insect and disease conditions in the United States, 1979-83 : what else is growing in our forests?. Forest insects United States; Trees Diseases and pests United States; Plants Disease and pest resistance. Mountain Pine Beetle Resources Affected Timber. All unmanaged stands of mature and overmature lodgepole pine, of second-growth mature and overmature ponderosa pine, of mature and overmature western white and sugar pines, and of overmature whitebark and limber pines are susceptible to at- tack. Dead trees must be salvaged for wood or fiber 3 to 5 years after they die; otherwise, they are often not worth salvaging. Some States have large areas of these susceptible, unmanaged mature or overmature stands. In Montana and northern Idaho, for example, an estimated million acres ( million ha) of mature lodgepole pine stands are highly susceptible. These susceptible acres include million acres ( million ha) of commercial lodgepole pine that could be ex- pected to yield million cubic feet ( million m3) of timber. Most of these acres are not planned for immediate timber harvest; many acres are presently inaccessible. Consequently, if in- festations continue to develop, spread, and intensify, the impact will be significant. In unmanaged forests, beetle- caused mortality eventually causes large portions of the com- mercial forest land to become understocked. Because much of this understocked area is inac- cessible, regeneration efforts would be time consuming and difficult. Widespread tree mortality resulting from outbreaks that last several years can influence the ecosystem. Rapid ecological changes take place over large areas; watersheds are adversely affected when pine canopies are destroyed; patterns of recreational use change; the supply of dead fuelwood increases; and valuable forests are converted to less desirable species. Figure 5. Trees killed by mountain pine beetle, Western United States from 1979 to Total: 79,661,117 Watershed. The
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