Annual losses from disease in Pacific Northwest forests.
| Authors: | T.W Childs, K.R. Shea |
| Year: | 1967 |
| Type: | Resource Bulletin |
| Station: | Pacific Northwest Research Station |
| Source: | Res. Bull. PNW-RB-020. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 19 p |
Abstract
This report presents current estimates of annual disease impact on forest productivity of Oregon and Washington. It is concerned exclusively with losses of timber volumes and of potential timber growth in today's forests.Annual loss from disease in this region is estimated at 3,133 million board feet or 403 million cubic feet. This is about 13 percent of the total annual growth including the mean periodic growth ~ of seedlings and saplings.' Of this loss, 162 million cubic feet is potential growth prevented by disease, 129 million is mortality, and 112 million is cull. West of the Cascade Range, annual loss is 234 million cubic feet, of which 92 million is cull from heart rots. East of the Cascades, annual loss is 169 million cubic feet, of which 91 million is growth loss and only 20 million is cull. More than half of the growth loss east of the Cascades is caused by dwarfmistletoes.
Greatest losses occur in Douglas-fir (139 million cubic feet annually), western hemlock (88 million), true firs (62 million), and ponderosa pine (40 million). Principal causes of loss are dwarfmistletoes (148 million cubic feet ), root rots (115 million), and heart rots (110 million).
Cubic-volume losses are now about equally divided between young growth and old growth. As young stands replace old ones, cull from heart rots will decrease but growthreducing diseases will become more important. Effective controls for some diseases are now or will soon be available, but most diseases will continue to cause heavy losses indenfinitely unless research efforts are made proportionate to the values at stake.