Influence of the Mountain Pine Beetle on the Composition of Mixed Pole Stands of Ponderosa Pine and White Fir

It is a well recognized fact that insects exert a powerful influence on the development and structure of a forest. Although many beneficial effects accrue from their activities, the changes which they bring about are frequently at odds with the desires of man. Losses of mature trees caused by insects are usually keenly realized because they deplete resources of present economic value; but less direct losses, which may occur concurrently, in stands of low present value, frequently pass unnoticed.