regeneration between plant communities, and identifying problem areas. I want to emphasize, however, that these results are broad averages and do not indicate the precise regeneration picture on any specific National Forest or Ranger District within the study area. Also, I would like to point out that the purpose of the survey was to compare and evaluate regeneration that has developed on mixed conifer clearcuts and is not to be considered as a recommendation for use of this silvicultural system to exclusion of others.

Generally, reforestation on these clearcuts has been quite satisfactory. The combination of advance, natural subsequent, and planted reproduction has resulted in adequate stocking on most of the clearcuts surveyed, and in overstocked conditions on some. It should be noted here that generally the forester's attention is focused on problems of establishing regeneration and too often the problem of an overabundance of trees is neglected. The early implementation of stocking level control is especially important for seral species such as larch and lodgepole pine where crowns quickly decrease in size and growth is lost if thinning is delayed.

Advance reproduction played a significant role in the Cascade mountain hemlock clearcuts where slash was not treated. Many mature stands in this plant community have a well-stocked understory of true fir and mountain hemlock saplings and poles. Even though suppressed for many years, vigorous, fully crowned understory trees will respond to release (Seidel 1977). It was evident that advance reproduction can be saved if felling and skidding operations are planned to minimize damage to the understory. Barrett

et al. (1976) have shown it is possible to save sufficient numbers of ponderosa pine understory during logging and slash disposal to form the new stand by marking understory crop trees before harvest and using unconventional slash disposal methods. Such techniques should be applicable to mixed conifer stands. where topography permits.

Natural regeneration established after clearcutting generally resulted in considerable numbers of seedlings, although in many cases distribution was patchy and seedlings were overtopped by brush. Despite the presence of many seedlings of natural origin on these clearcuts, relying on natural regeneration as the primary method of regenerating mixed conifer clearcuts is not recommended when intensive forest management is practiced. There is no assurance that natural regeneration will occur within any specific time period because of many factors such as seed supply and microclimate which are beyond the forester's control. If significant amounts of grass invade the clearcut before a good seed year occurs, probability of seedling establishment will decrease. In this study, woody vegetation (snowbrush, manzanita) was not a negative factor in seedling establishment but severely reduced growth of young trees.

In clearcuts where no advance reproduction exists or where it has been destroyed in the logging and slash disposal operations, planting is the obvious choice for stand establishment rather than relying on natural regeneration. Planting promptly restores the area to timber production before it is taken over by grass or woody vegetation, and enables the land manager to choose spacing to meet his objectives. At elevations below about 5,300 feet, ponderosa pine is clearly the preferred species to plant because its good survival and rapid growth rate result in full site utilization within a short period. In such plantations, ponderosa pine will be dominant for many years but in the long run a typical mixed conifer stand will result because of natural regeneration of other species and the trend of succession to more shade tolerant species. In higher elevation clearcuts, lodgepole pine is a desirable species to plant because of its greater resistance to snow damage. In the Blue Mountains, western larch appears to be a promising species to plant in higher elevation clearcuts, although surprisingly little larch has been planted in this area.

Establishment of mixed species plantations also reduces the chance of losing an entire plantation to insect or disease attacks. Of course, establishment of successful plantations is not a simple matter. It involves a complex series of operations including correct seed source, production of vigorous. nursery stock, proper lifting, handling, and storage of stock, careful planting procedures, and animal damage control. It is beyond the scope of this paper to discuss details of these many and varied operations. All regeneration foresters, however, would be well advised to read guidelines for plantation establishment prepared by Cleary et al. (1978).

If

In clearcuts where advance reproduction provides almost adequate stocking, natural regeneration could augment this stocking by filling in holes created by skid trails and slash disposal operations. natural regeneration is used to supplement advance reproduction, slash disposal should be minimized. This not only prevents unnecessary destruction of the advance reproduction but some slash on the ground creates a more favorable environment for seedling establishment by moderating temperature extremes. conclusion, because of the uncertainties associated with obtaining natural regeneration, it seems best suited as a supplemental rather than a primary method of regenerating mixed conifer clearcuts.

Literature Cited

In

Cleary, Brian D., Robert D. Greaves, and Richard K. Hermann (eds.). 1978. Regenerating Oregon's forests--a guide for the regeneration forester. Oregon State Univ. Ext. Serv., Corvallis, Oreg. 286 p., illus.

Day, Frank P., and Carl D. Monk. 1974. Vegetation patterns on a southern Appalachian watershed. Ecology 55:1064-1074, illus. Franklin, Jerry F.

1963. Natural regeneration of Douglas-fir and associated species using modified clearcutting systems in the Oregon. Cascades. USDA For. Serv. Res. Pap. PNW-3, 14 p., illus. Pac. Northwest For. and Range Exp. Stn., Portland, Oreg.

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