Silvicultural Systems and 9 Regeneration Methods: Current Practices and New Alternatives John C. Tappeiner, Denis Lavender, Jack Walstad, Robert O. Curtis, and Dean S. DeBell Development of Regeneration Practices 151 Early Logging Practices and Regeneration Methods 152 Studies of Natural Regeneration Processes 153 Artificial ConiferRegeneration 154 Producing Stands of Diverse Structures and Habitats 156 At Harvest 156 Young Stand Establishment 158 Regeneration inYoung to Mature Stands 158 Natural Succession 159 Conclusion 160 Literature Oted 160 In this chapter, we discuss silvicuItural systems and objective 1, and considerable wildlife habitat and regeneration methods to meet the needs of society other values can be provided while producing rela­ over the next several decades. We begin with a brief tively high yields of wood under objective 2. The history of silvicuItural systems and what we have knowledge and skills are available to pursue both ob­ learned about forest regeneration.in the Pacific jectives effectively. Moreover, many ownerswill likely Northwest. We then discuss how regeneration meth­ manage their forests under both approaches. ods might evolve over the next several decades. We believe that the practice of silviculture gen­ erally will be applied to two different forest man­ Development of Regeneration Practices agement philosophies and objectives, providing (1) old-forest characteristics and (2) wood production. Traditional methods for regenerating forests as part Significant amounts of wood can be produced under of a timber harvest fall into two broad categories: (1) 151 152 Section ll. Silvicultural Systems and Management Concerns even-age management systems, which include clear­ drew heavily on European experience and called for cutting, shelterwood, and seed-tree methods, and (2) intensive practices and detailed stand analyses. The uneven-age systems, which include single-tree and skills and techniques needed to implement this sys­ group selection methods. As part of these methods, tem were probably unrealistic for those times; how­ regeneration can be obtained by natural seeding or ever, it was used on federal lands. Sales were de­ planting, by release of advanced regeneration (Le., signed to remove less than 35 percent of the volume seedlings established in the previous stand), or by per stand (Munger 1950). Artificial regeneration and . coppice from sprouting tree species. tending of conifer seedlings to ensure adequate These methods all have been used successfully in conifer regeneration in unstocked parts of the stand western North America, and all will have their place were not part of this partial cutting system. in future forest management. They are the founda­ Debate over the use of partial cutting for Douglas­ tion upon which we will build new strategies to meet firwas quite lively (Munger 1950, Smith 1970). How­ society's desire for sustaining forests with old-growth ever, its use ended in the late 1940s. Munger (1950) characteristics as well as its demand for wood. reported that all new Bureau of Land Management and Forest Service timber sales called for clearcutting, except for the use of the shelterwood regeneration Early Logging Practices method and some selective cutting in southwestern and Regeneration Methods Oregon. Generally, early logging in the late 1800s and early Evaluation of partial cutting practices and studies 1900s was done to harvest high-quality commercial of natural regeneration helped establish the use of :1 timber at the least cost with little concern for refor­ clearcutting. Isaac (1956) evaluated a series of par­ estation, protection of soil or water, or provisions for tially cut old stands 5 to 10 years after cutting. Be­ aquatic wildlife habitat. Unmerchantable trees were cause of residual tree damage and mortality, v.,rind­ . left standing, logged areas often were burned, and throw, change in species composition from shade cutting frequently began at the bottom of a water­ intolerant to tolerant species, and lack of Douglas-fir shed and continued to the uplands until an entire regeneration, he recommended abandoning V1'ide­ basin was logged. Ironically, this pattern of cutting spread use of this system. He acknowledged that not .' may have more closely mimicked natural disturbance enough timehad elapsed to determine ifuneve n-age j> by large fires than the staggered-setting, dispersed management would eventually work on his study clearcutting approach that followed. Natural regen­ sites, but felt that in all probability there would be , ! H eration of woody plants follOwing early logging or in­ loss of growth and Douglas-fir stocking would be re­ ,II' tense fires readily occurred because mineral soil was duced. He suggested that partial-cutting or uneven­ lL exposed and seed was available fromresidual trees or age management might be appropriate for drier sites adjoining stands. Regeneration. however, varied from in southwestern Oregon, gravel soils of the Puget well-stocked. vigorous young conifer stands to dense Sound region, and severe southerly exposures else­ stands of red alder or sprouting hardwoods to dense where in the region (where moisture and shade are covers of shrubs with occasional conifers. A high pri­ critical factors). Smith (1970) suggested that th e un­ ority for early research was to provide methods for even-age system did not work in this region because conSistently regenerating forests after fires and tim­ "theoretical ecological considerations were not veri­ ber harvests. fied,thereby makingthe system inappropriate for th e .. The early effortsat developing silvicu1tura1 systems future." in the Pacific Northwest included both clearcutting In retrospect, use of partial-cutting, uneven-age (Hoffman 1924, Isaac 1956) and partial cutting (Kirk­ management was probably discontinued for land and Brandstrom 1936). Kirkland and Brand­ reasons: strom proposed a method for managing Douglas-fir and hemlock forests that partitioned the forest into • It was difficult and probably not appropriate to relatively small tracts that were planned for timber plement a single policy or approach over such a yield, logging systems, and regeneration. Their ideas range of forest stand oc nditions . 9. Silvicultural Systems and Regeneration Methods: Current Practices and New Alternatives 153 Inadequate attention was given to creating environ­ fine the regeneration niche (Grubb 1977).They pro­ ments and making use of treatments that would re­ vide a basis for understanding the response to silvi­ generate Douglas-fir and other conifer species. cultural practices. • Insufficient thought was given to leaving vigorous, undamaged trees to provide adequate growingstock. Evaluation of NaturalRegeneration Practices • Logging planning and technology were inadequate to implement Kirkland and Brandsrrom's (1936) Studies of natural regeneration were integrated with ideas, especially on steep slopes. evaluation of reforestation projects.This work evalu­ ated applied regeneration practices, identified prob­ • Unfortunately, partial-cutting, uneven-age manage­ ment ended abruptly. Its long-term use, even on lem sites, and helped to develop alternative regener­ some sites, could have provided usefulinformation to ation practices (Roeser 1924). Lavender et al. (1956) design other silvicultural systems.· examined naturalregeneration on staggered settings, and Franklin (1963) assessed natural regenerationon stripcuts, small patch cuts (0.25 to 4 acres); and stag­ Studies of Natural Regeneration Processes gered cuttings. Considerable work has been done on Although some of the veryearly work on reproduc­ regeneration using the shelterwood method (Tesch tion of western conifers was with planted seedlings and Manh 1991; Laacke and Fiddler 1986; McDonald (Munger 1911), most of it focused on natural regen­ 1983; Seidel 1983; Laacke and Tomascheski 1986; eration, in both undisturbed forests and clearcuts. McDonald 1976b; Gordon 1970, 1979; Williamson Hoffman (1924) and Isaac (1930, 1955) studied the 1973). McDonald (1976a) studied natural regenera­ dispersal of seed and the possibility or storage of tion in the Sierra Nevada of mixed conifers in all five conifer seed in the forest floor. Later work by Isaac principal regeneration methods, ranging from single­ (1938, 1940, 1943) focused on determining the envi­ tree selection to clearcutting. Minore (1978) and ronmental variables that control natural regeneration Stein (1981, 1986) examined regeneration results fol­ and identifying microsites that favor seedling estab­ lowing harvesting on sites considered difficult to re­ lishment. For example, Lavender (1958) studied the generate in southwestern Oregon. For example, Mi­ effects of seeding date and ground cover on the ger­ nore (1978) found that shelter prevented forest minationand survival of Douglas-fir in the Tillamook damage to seedlings and saplings on the Dead In­ bum. Hooven (1958) studied the effects of rodents dian Plateau in southwestern Oregon, and both 1vli­ and other predators on seed supply. Hermann and nore (1978) and Stein (1981) and Williamson and Mi­ Chilcote (1965) simultaneously studied the effects of nore (1978) pointed out the value of advanced seed bed, shadl::, and insect predation on conifer natural regeneration and natural seeding among seedling establishment, while Christie and Mack planted seedlings on sites with extreme variation in (1984) and Harmon and Franklin (1989) compared temperatures, such as those described byHolbo and dead wood and mineral soil as