other Forest Insect Problems Associated With 

 Forest Management Practices 



Forests of different age classes, like people, usually are troubled by different 

 problems, not the least of which in forest management are forest insects. Insect pests, 

 such as various species of bark beetles, that are usually the most serious enemies of 

 old-growth forests, are seldom troublesome in new forests of seedlings and saplings. 

 On the other hand, forest insects that kill or deteriorate younger trees often are 

 unknown or effect an insignificant amount of damage in the mature forest. Moreover, 

 there are some, like the western spruce budworm, Choristoneura oeaidentalis Freeman, 

 and the larch casebearer, Coleophora tarioella Hbn. , that have an impact, though 

 differentially, on all age classes of their host trees. With time, forest insect 

 problems of old-growth or overmature forests will wane in the northern Rocky Mountains 

 because current forest management practices are converting an increasing proportion of 

 commercial forest land into young even-aged forests of seedlings, saplings, and 

 pole-size trees. 



One example of such management practices is the planting of trees on what has 

 heretofore been nonstocked or nonproductive forest land. In 1970, for example, conif- 

 erous trees were planted on more than 34,000 acres in the northern Rockies. Much of 

 this acreage is considered to be some of the most potentially productive timberland in 

 the Nation but on which only brush had been growing--a situation created by repeated 

 wildfires over the years. 



These wildfires also have been responsible for the development of extensive forests 

 of western larch and lodgepole pine--two coniferous species that depend on fire for 

 their establishment and early survival (Beaufait 1971). These even-aged, often single- 

 species stands as such are predisposed to forest insect infestations, more so than young 

 uneven-aged, mixed conifer forests. Moreover, many of these stands are so dense that 

 they have stagnated to the point where they will never produce usable products. Many 

 of them no doubt will have to be destroyed and replaced by new trees (Wikstrom and 

 Wellner 1961) . 



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